Cromemco 4fdc Disk C..

Transcript

C R OM EM C O 4 FD C C R OM EM C O 24 0 0 Ch ar le ston D IS K COH TRO LLER TH C O R P O R A T E D R o a d , M o u n t a in V iew y C a l i fo rn ia TABLE C rom em co 1 . IN T R O D U C T IO N 2 - RDO S 3- RE G ISTE R 4- IN T E R F A C E 5 . PA RTS 6 . IN IT I A L 7 . THEORY 80 PA RT S 9 . WA RRANTY 4F D C OF CONTENTS Page l 2 D E S C R IP T IO N CHA RACT E R IST IC S PLA CEM EN T SE TUP OF 31 D IA G R AM 35 PROCEDU RE 36 OPE RAT ION L IST M AN U A L 11 40 44 46 c o p y r igh t 1977 by C r om em co , In c . 1 CHA PT E R 1: IN T R O D U C T I O N The Cromem co D isk Con tro ller (mode l 4FDC ) is des igned to in terface bo th s-in ch (''m in i'') an d 8-in ch floppy d isk d r iv e s t o compu ters . th e S - 10 0 com p u te r b u s u se d in C rom em c o In addit ion the 4FD C con ta in s a ser ial 1/0 ch an n e l w ith so ftw a r e -s e le c t a b le b au d r a t e s f r om 1 10 b au d t o 76 ,8 0 0 b a u d . T h e 4 F D C c on t r o l le r a l so h a s a IK r e s i d e n t 2 7 0 8 R 0 M p r e -p r o g r a m m e d w i t h C r o m e m c o 's R D O S R o Al- r e s i d e n t D i s k O p e r a t i n g S y s t e m . R D O S i s d e s i gn e d t o a l l ow a o p e r a t o r t o p e r f o rm a 1 1 e s sen t ia l d i sk op e r a t io n s from th e c on so le k ey b o ar d . R D O S a l s o c o n t a in s a b o o t s t r a p p r o g r a m t h a t c a n b e u s e d t o l o a d t h e p o w e r f u l C r o m e m c o C D O S d i s k o p e r a t in g sy s t e m in t o R M f m e m o r y f r o m a d i s k e t t e , F o u r s w i t c h e s o n t h e 4 F D C in t e r f a c e c a r d a r e u s e d to se t th e op e r a t ion o f th e c a r d . Sw i t c h 1 i s t h e R D O S D I S A B L E sw i t c h . W h e n t h i s sw i t c h i s O N t h e I K R 0 M c o n t a in in g R D O S c a n n o t b e a c c e s s e d b y t h e c o m p u t e r . W h e n t h i s s w l t c h i s 0 F F t h e R D O S p r o g r a m r e s i d e s in t h e c om p u t e T m em o ry sp a c e f r om a d d r e s s C 0 0 0 t o C SF F . Sw it c h 2 i s t h e R D O S D ISA B LE A F T E R B 0 0 T sw it ch . If t h i s sw i t c h i s 0 N t h e I K R 0 M c o n t a i n in g R D O S w i l l a u t o m a t i c a l l y b e d i s a b l e d a f t e r C D O S i s b o o t s t r ap p e d in f r o m a d i s k th u s c l e a r in g m e m o r y sp a c e f r o m C000 to CSFF for sy stem u se . is a c tu a l ly d is ab le d by an (1n th is m ode the R0M o u tp u t is don e au tom at ica lly by CDD S ) , RDOS r e m a in s in m em o ry sp a c e ev en to port 4 0H w h ich If sw it ch 2 is O FF , after CDO S is lo ade d . RDOS con tain s tw o p rogram s ; 1) th e CDO S bootstrap p rogram and 2) th e con so le m on itor p ro gram . Sw itch 5 is th e BOOT ENA B LE sw i t c h . W h e n th i s sw i t c h is 0N th e b o o t - strap p rog ram w ill execu te (thu s loa ding CDOS) w ithou t f i r s t e n t e r in g t h e m o n i t o r p r o g r a m . I f t h i s s w i t c h i s o f f , R D O S b e g in s in t h e c o n s o l e m o n i t o r m o d e p e rm i t t i n g t h e b o o t s t r a p o p e r a t i o n o r o t h e r o p e r a t i o n s t o b e p e r f o rm e d un de r c on so le c on tro l . S w i t c h 4 i s t h e IN IT IA L I Z A T I O N IN H I B I T s w i t c h . W h e n t h i s s w i t c h i s 0 N , d i s k e t t e s c a n n o t b e in i t i a l i z e d u n d e r s o f t w a r e c o n t r o l t h u s p r e v e n t i n g a ''r u n a w a y '' p r o g r a m f r o m u n i n t e n t i o n a l l y a l t e r i n g t h e d i s k e t t e in i t i a l i z a t i o n . T h i s s w i t c h m u s t b e O F F w h e n i n i t i a l i z in g d i s k e t t e s . B o th R D O S an d C D O S a r e w r it ten t o o f t h e Z - 8 0 m i c r o p r o c e s s o r in s t r u c t i o n d e t a i l s o n R D O S a r e g iv e n i n C h a p t e r 2 C D O S i s d e s c r ib e d in a s e p a r a t e m an u a l w i t h C r o m e m c o 's d i s k s o f tw a r e , t a k e fu l l a dv a n t a g e s e t . Com p le t e o f th i s m an u a l th at i s p r ov id e d . 2 CHA PTE R 2 : RDO S C opy r igh t The of RoM - re s ide n t 1 9 77 , C rom em co , D i sk O p e r a t in g In c . Sy s t e m has tw o modes oper at ion . I f the 4F DC bo a rd i s co nn e c te d to one o r m o r e d i sk dr iv e s e q u i p p e d w i t h t h e C R O M E M C O C D O S o p e r a t i n g s y s t e m a n d D I P sw i t c h 3 i s o n , th e m o n i t o r w i l l b o o t in th e o p e r a t in g s y s t e m fr o m th e d i sk w h en ev e r the com p u te r is re se t . I f sw i t c h 3 i s o f f , t h e m o n i t o r 's c o m m a n d m o d e i s a c c e s s e d b y r e se t t in g th e co m p u te r . T h is m o d e p ro v ide s co n tr o l o f th e c o m p u t e r f r o m t h e t e r m i n a l k e y b o a r d a t t a c h e d t o t h e 4 F D C 'S ser ia l po rt . T r a n s fe r of con tro l to a p ro gram anyw he re in m em o ry c an b e m a d e f ro m th e k e y b o a r d . C o m m a n d s a r e a l s o in c lu d e d t o d i s p l a y th e c o n te n t s o f m em o r y , c h an g e m em o r y v a lu e s r m o v e a n d c o m p a r e b l o c k s o f m e m o r y , e x am in e in p u t p o r t s , w r i t e d a t a t o o u tp u t p o rt s , an d ch an ge th e b aud ra t e o f th e se r ia l p o r t on th e 4F DC . T h e se c o m m a n d s m a k e th e 4 F D C d i s k d r i v e s fo r r u n n i n g t h e c o m p u t e r o r u s e fu l e v e n w i th o u t fo r d e b u g g in g h a r d - W a r e o There are also comm and s w h i ch c an b e a tt a c h e d t o t h e t o seek tr ack s , to sta r t in g an d to Com m and at any ch an ge re ad tr ack the to se le c t a n y o f 4F DC , to se t its o r w r ite and lo c a t io n b lo c k s o f m em o r y secto r , to of th e fo u r d r iv e s he ad seek rate , the boot in m o n i t o r 's to CDOS th e from d isk e t te d r iv e stack . F o rm a t T h e n o rm a l p ro m p t o f th e m o n i to r i s a sem i -c o lo n , ' ; ' H o w e v e r , i f a d i sk d r iv e i s se l e c te d th e p r om p t c h an g e s in o r d e r t o r e m i n d t h e u se r w h i c h d r iv e D i sk D r i v e fo r d e t a i l s . ) is cu rren t . (S e e - Se le c t T h e m o n ito r i s co n t ro l le d b y o n e an d tw o -c h a r a c te r co m m an d s fr om th e te rm in a l k e y b o ar d o T h e f o r m a t i s f r e e - fo r m w i th r e s p e c t t o s p a c e s A l l d a t a i s e n t e r e d a n d p r i n t e d in h e x a d e c im a l fo r m a t . A 3 In th e fo l l o w in g , D M i s th e Sw a th o p e r a to r e q u iv a le n t c om m an d s - is th e D i sp l ay (Se e b e low ) . They d i sp la y M em o ry comm and and S T h e f o u r e x am p le s a r e the con tents o f m em o r y b e g in n in g w i th lo c a t io n 1 0 0 0 h e x . ca rr ia ge re tu rn ) . of 100 hex by te s ( 1 (C R ) ' in d ic a te s ;DM l 0 0 0 I OF F (C R ) ;DM 10 0 0 S l 0 0 (C R ) ; D M 1 0 0 0 I OF F (C R ) ? D M 1 0 0 0 S 1 0 0 (C R ) W hen en t e r i n g an ad d re ss a s an d i g i t s t y p e d in a r e r e E a i n e d . '1 0 û 0 ' . T h e r e fo r e , i f a w r o n g u n t i l th e la s t fo u r d i g it s a r e o p e r an d , o n ly the last fo u r F o r e x a m p l e , '3 2 1 0 0 0 ' i s r e a d a s d i g it i s e n t e r e d , c o n t in u e t y p in g co r re c t . O n l y th e l a s t tw o d i g i t s t y p e d a r e r e t a in e d w h e n d i g i t n u m b e r su c h a s a d a t a b y t e i s e n t e r e d a tw o - . Sw a th Op e rator The re are co m m an d s . T he ad d r e s se s tw o w ay s fir st is to to sp e c i fy t h e s im p l y l i s t ad d re s s r an g e t h e b e g in n in g o f m any an d e n d in g (a n d , w h e r e ap p ro p r i a t e , t h e d e s t in a t io n a d d r e s s ) . F o r e x am p le , th e f ir s t co m m an d b e lo w d i sp l ay s th e c o n te n t s o f m e m o r y b e tw e e n a d d r e s s e s E 4 0 0 a n d E 4 0 2 T h e se c on d c o m m an d . move s (o r co p ie s ) th e f ir st 1 4 0 0 h e x by t e s o f m em o r y t o m em o r y s t a r t in g at 2000 hex . DM E 40 O E402 M 0 1 3F F 2000 A n o th e r w a y t o d o th e s a m e th i n g i s o p e r a t o r , S , t o s p e c i fy t h e w i d t h o f t h e to u se th e Sw a th ad d r e s s r an ge r a th e r t h a n s t a t e th e e n d in g ad d r e s s r x p l i c i t ly . DM E 4 0 0 5 3 M 0 51400 E rrors and 2000 E se ape s W h e n t h e m o n i t o r d e t e c t s a n e r r o r c o n d i t i o n i th e com m an d ' s ab o r t e d an d a '? ' i s p r in t e d fo l lo w e d b y t h e p r o m p t ' ; ' fo r th e n e x t co m m an d . A n y c o m m a n d m a y b e a b o r t e d fr om th e k e y b o ar d e i th e r w h e n th e m o n i t o r i s r e q u e s t i n g fu r th e r in p u t , o r d u r in g p r i n t - o u t , b y de p r e s s in g e i th e r th e E S CA P E o r th e A L T M O D K k e y CON T RO L. S E M I- C O L O N , Baud Rate s C O N T R O L - S H I F T - 'K ' and UA RT , an d ') ' m a y a l so w o r k . Se le c t io n W h e n th e m o n ito r i s m o n ito r r e sp on d s w ith : en te red , pu sh C ROM EM CO RDO S carr iage -return un til th e ( 4 T h e m o n i to r i s c a p ab le o f se le c t in g 1 9 2 0 0 , 9 6 0 0 , 4 8 0 0 , 2400 r 1200 , 300 , 150 , o r 1l0 baud . Th e m a x im um n um b e r o f c a r r l a ge - r e t u r n s r e q u i r e d to se le c t an y o f t h e se b a u d r a te s i s fo u r . Th e baud co m m a n d . r a te can a l so be ch an ge d by u s in g In i t i a l i ze (Se e b e lo w .) S o m e p e r ip h e r a l d e v i c e s su ch a s p a p e r t a p e r e a d e r s o r p u n c h e s m ay h a v e n o k e y b o a rd s . Th e b au d rate can a lso b e se t b y o u tp u t t in g a d a t a b y te fr om th e fo l l ow in g t a b le t o p o r t 0 . Baud Ra te s Data l10 l50 300 1200 2400 4800 960 0 port to The b aud 2. O u t p u t t in g c an 0 01 82 84 88 90 A 0 C0 be to o c tup led by th is po rt o u tp u t t in g b r in g s th e 10 b aud hex rate to b ack n o rm a l . Sy s t em 40 r ate Byte Stack T h e m o n i t o r 's s t a c k n o r m a l l y and 80 hex . How ev e r , i f it is r e s i d e s in low in th e w ay , it m em o ry can b e b e tw e e n m oved u s in g t h e K i c k S t a c k c o m m a n d . (s e e b e lo w ) Usin g th e Mon itor Se t the pow e r -on jum p sw itch on t he ZPU c ard to C b in a r y ) a n d t u r n o f f D I P sw i t c h th e Dep re ss carr ia ge -re turn UA RT o n th e 4F D C to b a u d Th e m o n i to r w ill then In by a from o rd e r boo t in t im e s in te r m in a l order b e in g to set u sed . r e sp o n d : p rom p t '; '. The th e k e y b o ar d . to 3 o n t h e 4F D C . tw o t o fo u r r a te o f t h e C ROM EM C O fo l l o w e d com m and s (1100 CDOS B RDO S m o n i to r fr om (C R ) is d r i v e -A then re ady s im p l y to ty p e r acce p t 5 COMMAN DS Boot (1 ) then B (C R ) Bo o t s C D O S fro m th e d i sk e t te o n r e s p o n d w i t h i t s p r o m p t 'A . ' m D i sp l a y (2a ) d r ive -A . CDOS w ill M em o ry DM b e g in n in g - ad d r e n d in g -ad d r (C R ) o r (2 b ) D M b e g in n in g - ad d r S sw a t h -w id th T h e c o n t e n t s o f m e m o r y a r e d i s p l a y e d in h e x a d e c im a l f o r m l in e o f kh e d i sp la y is p r e c e d e d b y th e a d d r e s s o f i t s E a ch f ir s t b y te . For e x am p le : ;D M 1 0 0 S 3 0100 : C 3 34 E x am in e (3 ) Inp u t 7F Po r t E p o r t- n um b e r D i sp l ay s th e b y p o r t -n um b e r (C R ) current con ten t s of th e in p u t por t id e n t i fie d (in h e x l - 9% (4 ) G s t a r t in g -ad d r Exe cu tion In i t i a l i ze (5 ) I - B aud be g in s (C R ) at s ta r t in g -a dd r e s s . Rate (C R ) A ft e r th e c ar r i a ge - r e t u rn i s typ e d , ch an g e t h e b a u d r a t e o f t h e t e r m in a l t o th e d e s i r e d v a l u e a n d th e n p u sh c a r r i a ge r e t u rn u n t i l th e m o n it o r re sp o n d s w i th it s p ro m p t . T h e m o n i to r i s c ap ab le o f se le c ti n g 1 9 2 0 0 9 6 0 0 , 4 8 0 0 , , 240 0 r 1200 , 3 00 , 150 , or 110 baud T h e m a x im u m n u m b e r o f c a r r ia ge r e t u r n s r e q u ir e d to se le c k an y o f th e se b a ud r a te s i s fo u r a . l 6 K i ck Stack (6 ) K n ew - s t a c k - lo c a t io n (C R ) to M o v e s t h e m o n i t o r 's s t a c k f r o m n o r m a l an y co n v e n ie n t lo c a t io n in R AM M em o r y . 64 (4 0 h e x ) b y t e s fo r Eh e s y s t e m st a ck lo c a t io n R em em b e r at to a b o v e i t s n ew 7C h e x le av e lo c a t io n (in c lu d in g 4 b y te s fo r t em p o r a r y s t o r a g e ab o v e th e st a c k p ro p e r ) . Move (7a ) M so u r c e - a d d r so u r c e -e n d d e s t in a t io n - a d d r (C R ) o r (7b ) M so u r c e - a dd r S sw a th -w id th d e s t in a t io n - a d d r Move (C R ) (o r c o p y ) th e co n te n t s o f m em o r y b e g in n in g w i th so u r c e - a d d r e s s a n d e n d in g w i t h s o u r c e - e n d t o d e s t in a t io n - a d d r e s s A fte r th e m o v e , t h e m o n i t o r v e r i fie s th a t so u r c e a n d d e s t in a t io n a re th e sam e . T h i s w i l l r e s u l t i n a p r in t - o u t o f d i s c r e p a n c i e s w h i c h a r e n o t r e a l ly e r r o r s a fte r c e r t a in t y p e s o f o v e r l ap p in g m o v e s H ow e v e r , t h i s p r in t - o u t c an b e t e rm in a t e d b y d e p r e s s in g E S C A P E o o ar ALT Mode . The move com m an d can be u se d to a c o n s tan t . F o r e x am p le , to e n te r an d 1 0 8 , u se th e Su b st it u t e M em o ry 1 0 0 , an d th e n m o v e 1 0 0 th r o u gh 1 0 7 M l00 l07 l00 S fill a b lo ck of m em ory w ith ze r o s b e tw e e n l o c a t i o n s l 0 0 c o m m an d t o en t e r 0 a t l o c a t io n to 101 : 1 0l o r M C ar e sh o u l d b e re s id e s in 1ow th e K i ck S t a c k taken not to 8 1 0l o v e rw r i te m em o ry b e tw e en com man d a 40 and th e 80 m o n i t o r 's hex u n le s s s t ac k w h ich ch an ged w i th Outp u t (8 ) O d a t a -b y t e p o r t -n um b e r W r i te s d a ta to hex ) . Re ad (9a ) (C R ) th e o u tp u t p o r t id e n t i fie d b y po r t -n um b e r D isk R D d e s t in a t i o n - a d d r d e s t i n a t i o n - e n d s e c t o r - n um b e r (C R ) o r (9b ) R D d e s t in a t i o n - ad d r S sw a th -w id t h s e c t o r - n um b e r (C R ) (in 7 B e fo r e th i s com m an d w ill be ac cep te d t r a c k n um b e r m u s t h a v e b e e n sp e c i f ie d . D r iv e an d Se e k c o m m an d s b e low . ) th e d isk d r iv e and (S e e t h e S e l e c t D i sk Re ad s en o u gh se c to r s fro m th e cu r re n t d r iv e to f i1 1 th e s p e c i f ie d m e m o r y a r e a # s t a r t in g w i th t h e s p e c i f ie d se c t o r o f th e c u r r e n t t r a c k . P r in t s th e f ir st t r a c k an d se c t o r a n d th e l a s t t r a c k a n d se c to r r e a d . H ow ev e r , i f th e la st se c to r o f th e l a s t t r a ck i s f i l le d th e n on th e d iske t te a que stion m ark i s r e ad b e fo r e i s p r in t e d a n d th e m em o r y a re a th e c om m a n d i s te rm in a te d T h e c o m m an d i s a l so te r m in a t e d i f an r e ad in g a se c to r . In th i s c a se , a m e s s a g e ty p e is p r in te d : R-ERR w h ere nn is a hex number w h ich nn ind ic a t e s B it e r ro r i s re ad in o f t h e fo l lo w i n g th e sta tu s : In d ic a t io n 7 Not Re ad y 6 Re co rd Type 5 Re co rd Type 4 Reco rd Not 3 CRC 2 Lost Data 1 Da ta Reque st 0 Busy Found Erro r T h e n um b e r o f th e la st tr ack ac c e s sed c an b e ob ta in ed from in p u t p o r t 3 1 h e x an d th e n u m b e r o f t h e l a s t s e c to r a c c e s se d fr o m in p u t po r t 32 h e x . (S e e th e E x a m in e Lar ge F lo p p y In p u t P o r t c o m m a n d o ) M in i F lo p p y T rack s 0 - 4C hex 0 - 27 hex Se ctor s l - IA hex 1 - 12 hex C a r e s h o u l d b e t a k e n n o t t o o v e r w r i t e t h e m o n i t o r 's s t a c k w h i ch n o r m a l l y r e s i d e s i n l o w e r R A M b e t w e e n 4 0 a n d 8 0 h e x If i t i s d e s ir ab le to lo ad th i s re g io n o f m e m o r y fr om th e d i sk , f i r st m o v e th e st a c k u s in g th e K ic k S t a ck c o m m a n d . o 8 Seek T rack (10 ) S tr a c k -n um b e r B e fo r e th i s com m and h av e b e e n sp e c i fie d . se e k s the I f an p r in t e d : w he re nn a hex (1 1 ) track i s m ad e , a n um b er B it Sub st itu te w ill be ac ce p te d th e d i sk d r iv e m u st (Se e th e S e l e c t D i sk D r iv e co m m an d b e low .) sp e c i f ie d error is (C R ) of the m e s sa ge cu rren t of the S -E R R nn wh ich in d i c a te s d r ive . fo l l o w in g the ty p e is statu s : In d i c a t io n 7 Not Ready 6 W rite 5 H e ad En g a ge d 4 See k Erro r 3 C RC 2 Track 1 In d e x 0 Bu sy Pro tect E rro r 0 M em o ry SM ad d r e s s (C R ) Su b st i t u t e M e m o r y d i sp l a y s th e c o n t e n t s o f ad d re s s a n d o utp uts a do t ' . ' , a s a p ro x p t fo r t h e s u b s t i t u t e d v a l u e If r n o c h an g e i s d e s i r e d , ty p e a sp a c e o r a n o t h e r d o t . Othe rw i se , e n te r th e n ew v a l u e . The mon ito r accepts hex d ig its u n t i l i t g e t s a d e l im i t e r , s u c h a s a s p a c e , d o t , o r c a r r i a g e r e t u r n l r e t a in in g t h e l a s t tw o d i g i t s e n t e r e d a s t h e v a l u e U n l e s s t h e d e l im i t e r i s a c a r r i a g e - r e t u r n , th e m o n i to r th e n o u t p u t s th e c o n t e n t s o f t h e n e x t s e q u e n t i a l m e m o r y lo c a t io n w ith a do t p rom p t . A c a r r ia ge - r e tu rn t e rm in a t e s th e c o m m a n d - o . V e r i fy (1 2 a ) V so u r c e - a d d r s o u r c e - e n d d e s t in a t i o n - a d d r (C R ) o r ( (l 2b ) V so u r c e - ad d r S sw a th -w id t h d e s t in a t io n - a d d r (C R ) 9 and n in g V e r i fy t h a t t h e b l o c k o f m e m o r y b e t w e e n s o u r c e - a d d r e s s so u r c e - e n d c o n t a in s k h e s a m e v a lu e s a s t h e b lo c k b e g in - at d e s t in a t io n - ad d r e s s . The add re s se s p r in t e d fo r e a c h d i s c r e p an c y fo u n d t e r m in a te d b y E S C A P E o r A L T M O D E ) and co n ten t s (u n l e s s th e p r in t -o u t are is T h i s c o m m a n d w o r k s b y r e ad in g b y t e s fr o m t h e s o u r c e a n d d e s t i n a t io n a n d c o m p a r in g t h e m . I f a d is c r e p an cy i s fo u n d , th e m e m o r y i s r e ad a g a in fo r p r in t - o u t Thu s it c an h ap p en t h a t a d i s c r e p a n c y i s p r in te d - o u t w i t h th e so u r c e a n d d e s t in a t io n c o n te n t s in d ic a t e d to b e th e s am e . T h i s i s ca u se d b y a d e f e c t i v e m e m o r y e le m e n t W r ite D i sk (1 3a ) WD so u r c e '-a d d r so u r c e -e n d se c t o r -n um b e r (C R ) o r Xx = st WD sou r ce S sw a t h -w id t h se c t o r -n u m b e r (C R ) '- kk gï j (l 3b ) M z Before this command will be accepted the disk drive and track number must have been specified . (See the Select Disk D r iv e a n d S e e k c o m m a n d s o n p r e v i o u s p a g e -) W r i t e s th e c o n te n t s o f t h e sp e c i f i e d m em o r y a r e a to c u r r e n t d r iv e , s t a r t in g w i t h th e sp e c i f i e d se c t o r o f t h e the curren t tr a ck m P r in ts th e f ir s t se c to r w r itten . How ev a fte r th e l a s t se c to r m a r k is p r in t e d an d th in g t r a c k a n d s e c t o r ap d t h e l a s t t r a c k a n d e r , i f p a r t o f th e m em o ry a r e a rem a in s o f t h e l a s t t r a c k i s w r i t t e n , a q u e s t io n e c o m m an d i s t e r m in a t e d . Th e co m m an d i s a l so t e rm in a te d i f a se c to r o In th i s c a s e , a m e s s a g e a n e rr o r i s m ad e o f th e fo l lo w in g m ade : W -E RR w h e re nn is a hex num b e r nn in d i c a t in g Bit the statu s : In d i c a t i o n 7 Not Re ady 6 W r ite P ro te c t 5 W r i te Fault 4 Re co rd 3 C RC 2 Lo st Data l Data Reque st 0 B u sy Not Found Error in w r i t typ e is 10 The la st track a c c e s se d c an b e o b t a in e d fr o m port 31 hex . T h e l a st se c to r a c c e s se d fro m p o r t 32 h e x . (S e e E x am in e c o m m a n d .) L ar ge Se le c t F lo p p y M in i F lo p p y Track s 0 - 4C hex 0 - 27 hex se c to r s 1 - IA hex 1 - 12 hex D isk In p u t D r iv e T h e 4F D C w i l l co n t ro l u p to fo u r d i sk d r iv e s , la b e l le d ''A 'V ''B '' F ''C '' ; a n d ''D '' e I t c an h an d le se e k sp e e d s fr om th e s low se e k ap p r o p r ia te t o t h e m i n i f l o p p y t o t h e f a s t s e e k o f C r o m e m c o 's la r g e flo p p y . It c a n a l so h a n d le t h e m e d i um se e k o f so m e o th e r la r g e flop p ie s . T o s e l e c t a d r iv e a n d a s e e k sp e e d , t y p e t h e d r i v e l a b e l fo l l o w e d b y o n e se m i - co l o n fo r t h e f a s t se e k , a n d tw o s e m i - c o l o n s f o r m e d i u m s e e k , o r t h r e e s e m i - c o lo n s f o r s l o w s ee k . F o r e x am p le , t o se le c t d r iv e C w i t h s lo w se e k , t y p e : C ; ; ; (C R ) To se le ct d r iv e A w i th fa st s e e k , typ e : A; U n t il the d r iv e (C R ) se l e c t io n i s ch an ge d the n o rm a t m o n i to r p r o m p t , 1; 1 , w i l l b e r e p l a c e d by th e d i sk l ab e l d i c a t o r a s t y p e d , 'C ; ; ; ' i n t h e f i r s t e x a m p l e . A l 1 d i sk eo m m a n d s to th e drive D i sk mo st speed in - (Se e k , Re ad D i sk , an d W r it e D i sk ) r e fe r recen tly se le ct ion and a l so se lected . re sto re s th e d i sk d r iv e h e ad to home , track 0 . fo l l o w in g I f an e r ro r is m ade ty p e i s p r in te d : in H -E RR where nn is a hex n um b e r B it d o in g th is a m e ssage nn ind ic a t in g th e s ta tu s : In d i c a t i o n 7 Not Re ad y 6 W r i te 5 He ad En g aged 4 seek Error 3 CRC 2 Track 1 In d e x 0 Bu sy Pro te st Erro r 0 o f the 11 CHA PT E R Th e re g iste rs o f 3: RE G IST E R D E S C R IP T IO N th e 4 FD C w il l b e d is cu s se d in n um e r ic a l o rder accord in g to th e ir l/0 addre ss a s s ignm en t sh own b e low ; 1/0 A dd re ss (hex ) 00 IN INPUT OUTPPT 00 01 02 UA RT statu s UA RT d ata n o t a s s ign e d UART UAR T UA RT 05 in t e r r u p t in t e t r u p t m a s k 04 p a ra lle l inp u t a d dr e s s b au d r a t e data c om m an d p ar a lle l ou t/aux ilia ry d i sk c o m m an d t im e r 1 tz m e r 2 t im e r 3 t ys e r 4 05 n o t a s s ign e d :6 gy :8 ig 50 u r, ,t u D ISK u ,, yy u s ta tu s t sm e r s D ISK comm an d 51 D IS K track D ISK t r a ck 52 55 34 D ISK D IS K D ISK sector data f la g s D ISK D IS K D IS K se c to r data con t ro l 40 n o t a s s i gn e d b an k se lect S t a tu s R e g i s t e r : B it a s s ign m e n t b y T ran sm i t Re a d In t , Sta rt Bu f fe r Data P en d - B it Em p ty A v a i l . in g Detect T h e fu n c t i o n s o f low in g se c t ion s . th e s e fla gs Fu l l B it De tect are P C board traces , Se r - O v e r - F r am e ia1 Run Error R cv . E rr o r in d i c a t e d in th e fo l - #; Transm itter Buffer Empty (TBE) : A h igh in bit b u f fe r is re ady as the se r ia l 7 in d i c a t e s th a t th e to a c c ep t a n ew b y t e . t r an sm i t t e r b e g in s to t r an sm i t te r T BE sen d go e s h igh th e by te da ta a s so on c u r r e n t ly in t h e b u f f e r . S in c e t h e t r a n sm i t t e r i s ''d o u b l e -b u f f e r e d '' th e u se r m ay r e sp o n d t o t h e T B E s ign a l a n d lo a d t h e b u f f e r > 12 even before the p rev iou s byte has been totally tran sm itted . T BE th e a l s o a c t i v a t e s in t e r r u p t r e q u e s t 5 . TBE b u f fe r i s lo a d e d an d i s se t b y th e R E SE T A s c lea r e d w h en com m an d . Pé Recelver Data Available (RDA ) : A h i g h in b i t 6 in d i c a t e s t h a t a b y t e o f d a t a i s a v a i l ab l e f r om th e r e c e iv e r b u f f e r . T h i s f l a g r e m a in s h i g h u n t i l th e b u f fe r i s T e a d . A R E SE T c om m an d c le a r s th e f l a g . lf t h e b u f f e r i s n o t r e a d b y t h e t im e t h e n e x t b y t e f r o m t h e receiver is ready , the new byte w ill w rite ov er the o1d byte an d th e o v e r ru n in t e r r u p t e r ro r request flag w ill b e se t . 2 DA also a c t iv a t e s 4. #é lnterrupt Pending (IPG) : A h i g h in b i t 5 in d i c a t e s t h a t o n e o r m o r e o f t h e e i g h t in t e r r u p t r e q u e s t s o u r c e s h a s b e c o m e a c t i v e . Th is fla g goe s h i g h a t t h e s a m e t im e a s t h e in t e r r u p t r e q u e s t p in o f t h e TM S 5501 UA RT . #i Start Bit Detect (SBD): A h i g h i n b i t 4 in d i c a t e s t h a t t h e s e r i a l r e c e i v e r h a s de te c te d a s t a r t b it T h i s b i t r em a in s h i g h u n t i l t h e fu l l c h a r a c t e r h a s b e e n r e c e iv e d , S B D is c l e a r e d b y R E SE T c om m an d T h i s b i t is p r ov id e d fo r t e s t p u rp o s e s . Pé Full Bit Detect (FBD) : T h e F B D f l a g in b i t 5 g o e s h i g h o n e f u l l b i t t im e a f t e r th e s t a r t b it h a s b e en d e t e c t e d T h i s b i t r e m a in s h i g h u n t i l t h e f u l l c h a r a c t e r h a s b e e n r e c e iv e d . FBD is c le ar e d by a RE SE T c om m an d . T h is b it i s p ro v id e d f o r t e s t p u rp o s e s . P; Serial Receive (SRV ) : A h i g h i n b i t 2 in d i c a t e s h i g h l e v e l o n t h e s e r i a l d a t a in p u t l i n e . A 1 o w in b i t 2 in d i c a t e s a 1 o w l e v e l o n t h e s e r ia l d a ta ln p u t l in e . S R V i s h i gh w h e n n o d a t a i s b e i n g r e c e iv e d . T h is b it i s p rov ide d fo r b re ak d e t e c t ion an d fo r te s t p u rp o se s . #1 Overrun Error (ORE) : th e A h i g h in b i t 1 in d i c a t e s t h a t t h e r e c e iv e r h a s l o a d e d r e c e iv e r d a t a b u f f e r b e fo r e t h e p r e v i o u s c o n t en t s w e r e . 13 read . 0RE is c leare d th e R E SE T c om m an d . a fte r th e st atu s p o r t is read o r by P# Frame Error (FME ) : A h i g h in b i t 0 in d i c a t e s a n e r r o r in o n e o r b o t h s t o p b i t s w h i c h ''f r a m e d '' t h e l a s t r e c e i v e d d a t a b y t e . r e m a in s h i g h u n t i l a v a l i d c h a r a c t e r i s r e c e iv e d . 00 0U T B au d R a t e R e g i s t e r : F R W Y r a t e an m it data . ST O P B IT S D7 se t s the st op b it s fo r s e r i a l r e c e iv e an d t r an s - B it 96 00 L o a d in g t h i s r e g i s t e r o f th e FM E a s s i gnm en t 4 800 2400 i: as fo l low s : 1 200 500 150 110 ST O P A h i gh in b i t 7 se l e c t s o n e s t o p b i t f o r s e r i a l r e c e iv e an d t r an sm i t d a t a . A 1 ow in b it 7 s e le c t s tw o st op b i t s . D 6 -D 0 BAU D RATE A h i gh in o n e o f t h e l ow e r s ev en b i t s s e l e c t s t h e c o r r e s p o n d in g b a u d r a t e . If m o r e th an on e b it i s h i gh , t h e h i gh e s t r a t e s e l e c t e d w i l l r e su l t If n o n e o f th e b i t s a re h i gh , th e s e r i a l t r an sm i t t e r . an d receive r w ill be d isab led . p u rp o s e s , t h e s e b a u d r a t e s c an (For sp ec ial b e oc tup le d - - se e the descr ip t ion o f HBD in the comn and register ) : 01 IN R e c e iv e r D a t a : T h i s r e g i s t e r c o n t a in s a n y te o d a t a f r o m t h e s e r i a l r e c e iv e r . 01 0UT T r an sm i t t e r D a t a : T h i s re g i s t e r o r t e se r i a l t ra n sm i t t e r . is a s s em b l e d lo a d e d w i th data 1 02 IN N o t A s s ig n e d : R e a d in g t h i s p o r t c a u s e s n o r e sp o n s e fr om th e 4 F D C . T h i s a d d r e s s i s av a i l ab l e f o r o th e r p a rt s o f th e com p u t e r sy s t em . 14 02 0PT C qE E / Id R e ister : T h e fo rm a t fo r th e com m an d r e g i s - - ter is P1 s ow n PA PA Not Not B se d U se d as fo l low s : PA T e s t H IGH BA U D PA IN T A En ab le PA P1 R ST 7 Break Se l . PX Re se t Pâ Test Bit (TB5) : A h i g h in l o g ic an d t h en o n t h e IN T p in b i t 5 d i s a b l e s t h e i n t e r n a l in t e r r u p t p r i o r i t y e n a b l e s t h e in t e r n a l c l o c k . T h u s , t h e s i gn a l o f th e S 50 1 b e com e s a T T L lev e l c lo ck o f 156 2 .5 H z (12 .5 kH z if HBD is h igh -- see D 4 H igh Bau d b e low ) . TBS sh ou ld be 1 ow fo r n o rm a l op e r a t ion . #A High Baud (HBD) : A h i g h in b i t 4 o c t u p l e s t h e r a t e o f t h e i n t e r n a l c l o c k . T h i s c a u s e s t h e in t e r v a l t im e r s t o c o u n t e i g h t t im e s f a s t e r a n d t h e s e r i a l d a t a r a t e s t o in c r e a s e e i g h t - f o l d . W h en b it 4 i s h i g h , b a u d r a t e s u p t o 7 6 , 8k a r e a v a i l a b l e f o r h i g h sp e e d d a t a t r an s f e r s . #â INTA Enable (INE) : A h i g h i n b i t 5 a l l o w s t h e 5 5 0 1 t o r e sp o n d t o a n In t e r r u p t A c k n o w l e d g e b y g a t i n g a R e s t a r t i n s t r u c t i o n i n t o t h e d a t a b u s a t th e c o r r e c t t im e an d r e s e t t i n g i t s in t e r n a l in t e r ru p t r e qu e s t l a t ch . A 1 o w in b i t 5 p r e v e n t s cy c l e . B i t 5 sh ou l d b e h igh th e 5 5 0 1 fr om d e t e c t in g fo r n o rm a l op e r a t ion . an IN T A #; RST 7 Select (RS7) : A high in b it 2 connects the M SB of the parallel input port to the interrupt request latch for the lowest p riority An terrup t (in terrup t 7) . A low -to -h igh tran sit ion on J h e M SB o f the p aralle l input p ort (P I7) w ill act iv ate th e in ter rup t request latch . The 4FDC p rov ide s an op tion al jump er to conn ect DRQ from the d isk to P I7 . Th is jump er is lab e lled ''INTER 7,'. from th e Wh en th e jump er is in serted an d RS 7 is h igh , DRQ 'S d i sk w i l l g e n e r a t e in t e r r u p t s . 15 N A 1 o w in b i t in t e r r u p t r e q u e s t (interrup t 7) . 2 c o n n e c t s t h e o u t p u t o f T im e r 5 t o t h e l a t c h f o r th e l o w e s t p r i o r i t y in t e r r u p t When the tim er coun t reach es zero , th e in t e r r u p t T e q u e s t l a t c h w i l l b e a c t iv a t e d . #A Break (BRK) : A h i gh in b i t 1 h o ld s th e th e 1ow state (sp acin g ) . below ) . A 1 ow 1ow in b it s e r i a l t r an s m i t t e r o u t p u t in RE S w ill ov err ide (see D 0 Reset 1 a l low s n o rm a l op e r a t ion . BRK sh o u l d b e f o t n o rm a l op e r a t io n . P# Reset (RES) : A h igh a) in b it 0 c au se s f o l l o w in g a ct ion s : Th e Serial R eceiver goes in to se arch m ode ; RDA , SBD , F B D , an d 0 R E a r e se t t o r e c e iv e r b u f f e r a r e n o t b) th e ze r o . The a f fe c te d . con t en t s of th e The Serial Tran sm itter output is set h igh (m ark ing) , l f D 0 a n d D 1 a r e b o th h i g h , t h e R 2 S fu n c t i o n w i l l o v e r r id e . c) RE S 05 IN h i gh , The in terrup t re gister is cle ared excep t for th e TBE in t e r r u p t d) se ts T BE re qu e s t w h ich is set h igh . The in terv al tim ers are cleared . RE S is n ot latch ed . In t e r r u t A d d r e s s : T h i s r e g i s t e r c o n t a in s t h e e n co e a ress o t h e h i g h e s t p r i o r i ty in t e r r u p t c u r r e n t l y r e q u e s t in g s e r v i c e . Th is address is iden t ica l to th e th e in t e r r u p t ''R e s t a r t '' i n s t r u c t i o n a ckn ow l e d g e , T h u s , th e o p -c o d e fo r re g is te r con tents may be (in order of serv ice priority ) : HEX SO U R CE f C7 --- T im e r 1 CF --- T im e r 2 D 7 --- En d o f job (From d isk ) DF E7 EF F7 --- ----- T im e r 5 R e c e iv e r D a t a A v a i l ab l q T r an sm i t t e r B u f f e r E m p t y T im e t 4 FF --- T im er 5 or (DRQ From D isk ) 16 T h i s r e g i s t e r i s p r o v i d e d f o r s e r v i c in g in t e r r u p t s v i a o l l in g . A f t e r t h e r e g is t e r is r e a d , t h e c o r r e sp on d in g b i t P is re set I f t h e r e g i s t e r An t h e i n t e r r u p t r e q u e s t r e g i s t e r i s r e a d w h e n n o in t e r r u p t i s p e n d i n g , i t w i l l r e a d O F F H . . 05 OU T In t e r r u t M ask : The c on t en t s o f t h i s re g iste r are lo g ic a l y W x F A''-e d w i th o u tp u t f r om th e in t e r ru p t re qu e st r e g is te r on th e 55 0 1 . A h i g h b i t in th e in t e r r u p t m a s k a l l o w s t h e c o r r e sp o n d in g r e q u e s t t o p a s s o n l n t o th e p r i o r i t y e n c o d e r . A 1ow b it in t h e in t e r r u p t m a s k in h ib i t s t h e c o r r e sp o n d in g i n t e r ru p t f r o m p a s s in g a n y fu r t h e r . S in c e t h e in t e r r u p t r e q u e s t s a r e l a t c h e d in d e p e n d e n t l y o f t h e s t a t e o f th e m a sk , an in t e r ru p t m ay b e r e qu e s t e d w h i l e t h e m a sk b it is l ow . T h e r e q u e s t w i l l b e r e t a in e d u n t i l t h e m a s k i s c h an g e d a n d t h e r e q u e s t a l l o w e d t o p a s s on (assum in g n o RE S comm an d in the in terim ) . m a sk T im e r b it 5 T im e r a s s ignm en t s 4 TBE RDA Th e are : T im e r 5 E0J T im e r 2 T im e r 1 D RQ 04 IN P arall el p r e s en t e d In p u t ; at J4 , T h i s r e g i s t e r c o n t a in s t h e d a t a Tw o b its are re s e rv e d fo r th e 4FD C . DRQ SEE K IN X X X X X X PROGRE SS D 7-DRQ (jump er op t ion ) A h i g h in b i t s e v e n i n d i c a t e s t h e D I S K d a t a T e g i s t e r , P O R T 5 5 H ? i s r e q u e s t in g s e r v i c e . Th is s i g n a l i s a l s o a v a A l a b l e a t p o r t s 5 0H a n d 3 4 H . DRQ is p rov ided at b it sev en of p ort 04 so that the RS 7 m ode of th e UA RT m ay b e selected (see descrip t ion of RS 7 ; bit 2 of port 2) if interrupt dr iven disk r ou t in e s are re qu ir e d . W h en sh ip p e d , t h e 4FD C does n ot h ave the en ab lin g jump er in se rted . In o rder to u se D 7 a s de scr ib ed h ere , in sert jump er ''INTER 7'' ju st be low J 4 . 96 - SE E K IN P RO GR E S S in A h i g h in b i t s ix i n d i c a t e s t h e v o i c e c o i l m o t o r t h e c u r r e n t l y s e l e c t e d d r i v e i s in m o t i o n . 17 A 1 o w i n b i t s ix h a s s t o p p e d m o v in g in in d ic a t e s th e v o i c e c o i l m o t o r th e cu r ren t ly se le c ted d r iv e , T h i s s i gn a l i s o n ly m e a n in g fu l w h e n t h e c u r r e n t ly s e l e c t e d d r i v e h a s a v o i c e -c o i l h e a d s t e p p e r m otor (e .g . PER SC I 277) , w il l f l o a t h igh th tou gh ln a11 o th er cases , it th e 1 50 o hm p u l lu p to +5 v olts . D 5 -D 0 u n a s s i g n e d T h e b o t t o m s ix in p u t b i t s a r e f r e e f o r s y s t e m u se . T h e in p u t d a t a m u s t s t a b i l i z e w i t h in 7 5 n s after Input Strob e/ goes 1ow an d rem ain stab le un til Inpu t Strob e/ goes h igh again . 04 0U T P I LI 11 - -I1 Output/Auxiliary Disk Command : - r e g ist e r con t a ln s t e outpu t bu ffers . ' -E J . -E J . -F A S T LE FT SEE K R IG H T v----- -N o t a s s i gn e d D6 -E J E C T one -R E S T O R E -C O N T R O L X X action , A 0P T P E R S C I 2 7 7 O P T IO N S - - - - - * D7 A r zv e s th e p a r a l le l D ata is stab le after Output Strobe/ T is e s - X a ta- ë v T c This LE FT in b i t s ix cau se s n o zero in b it six activ ate s the eject le ft l in e o f J 2 . Th is b it on ly affect s Persci 277 driv e s w ith remo te eject o p t ion . D5 Th is b it -E J E C T A on e i s n o r m a l ly h i g h . R IG H T in b i t f iv e c a u s e s n o a c t i on . A zer o in b it five activates th e eject righ t lin e of J2 . Th is b it on ly affects P ersci 277 driv es w ith rem ote eject o p t io n . Th is b i t D4 -FA ST b it A o n e in b i t fou r p u t s th e i s n o rm a l l y h i gh . SEE K fou r c au se s n o a ct ion . A ze ro F D 1 7 7 1 in t o f a s t s t e p m o d e a s in 18 n e e d e d b y v o i c e c o i l d r iav e s , D 4 sh o u l d b e r e t u rn e d t o l o g i c 1 a f t e r t h e d r iv e h a s s i g n a l l e d s e e k c o m p le t e . T h i s b i t i s n o r m a l ly h i g h . D5 -R E S T O R E A on e in b i t f o u r c au s e s n o a c t io n . A ze r o b i t f o u r c au s e s t h e e u r r en t ly s e l e c t e d d r iv e t o r e tu rn t o T r a ck 0 0 . T h i s b i t i s n o r m a l ly h i g h in . D2 -C O N T R O L A h i gh 0U T in b i t 2 c au se s n o a c t ion A . 1 ow in bit 2 pulls down p in 1 of J1 the priority Daisy C h a in . Th is b it D 1 yD 0 -N o t 0S IN i s n o rm a l l y h igh . a s s i gn e d N o t Co nn e c te d ; A d d r e s s in g t h i s p o r t c a u s e s n o r e sp on s e rom th e 4 FD C . T h i: a d d r e s s i s av a i l ab le f o r u se by o th e r p a r t s o f th e c om p u t e r sy st em . 0S 0UT Timer i : This register contains the count used to s t a r t T lm e r 1 . Th is co un t i s d e c rem en te d by 1 ev e ry 6 4 p s e c o n d s a f t e r in i t i a l l o a d in g W h e n th e c o u n t r e a c h e s z e r o , b i t 0 o f t h e in t e r r u p t r e q u e s t r e g i s t e r i s s e t an d t h e t im e r d i s a b l e d S in c e t h e m a x im u m c o u n t i s 2 5 5 , t h e l o n g e s t in t e r v a l i s 2 5 5 x 6 4 . . psecon ds = 1 6 .3 2 m s e c o n d s A c c u r a c y i s p l u s 0 an d m in u s 6 4 g se co n d s . L o a d in g a c o u n t o f ze r o c a u s e s a n im m e d i a t e in t e r r u p t r e q u e s t t o t h e in t e r r u p t r e qu e st re g i ste r . L o a d in g a n ew c o u n t w h i l e th e t im e r i s c o u n t in g T e in i t i a l i z e s t h e t im e r w i t h o u t an interrupt reguest . r e g ist e r , th e . If HBD is h igh in the command t im e r s w i l l cou n t e igh t t im e s as fast . 06 IN N o t Conn ec te d : S am e as ln p u t 05 . 06 0UT Timer > ; 07 IN Not Operates in the same fashion as timer 1 C onn e c t e d : Sam e as ln p u t . 05 . 07 0UT Tiper é : Operates in the same fashion as timer 1 , 19 08 IN Not Conn ected : S am e as In p u t 05 . 08 0UT Timer i : 09 IN Not 09 0UT Timer * : 50 IN D i sk S t a tu s : T h i s r e g i s t e r 's b i t a s s i gn m en t v a r i e s a c c o r in g t o t h e l a s t c o m m a n d l o a d e d i n t o t h e d i s k com m an d p o r t . T h e r e a r e s ix p o s s ib l e a s s i gn m e n t s ; Operates in the same fashion as timer 1 , Con n e c te d : Sam e as In p u t 05. Operates in the same fashion as timer 1 Last Command p.l p-q p.y SE E K , ST E P , o r N ot R e a dy W r ite H e'a d P T o t e c t D ow n p.l p4 p-l Not F ou n d CR C TK E r ro r 00 pl p4 ln d e x Bu sy R E ST O R E READ RECORD IS) Not Record Ready Typ e W R ITE RECORD IS) Not W r ite W r ite Ready Protect Fau lt No t C RC Lo st D RQ Found E rror D ata Bu sy REA D Not Not CR C Lo st DRQ Bu sy A D D RE S S Ready Foun d Error D a ta READ Not 0 0 Lo st DRQ TRACK Ready W R ITE Not TRACK Re ady 97 0 0 0 0 Bu sy Bu sy Data P rote c t W r ite -N O T A Reco rd N o t CR C Lo st DRQ Typ e Foun d E rro r Data 0 0 F au lt Lo st D RQ Bu sy Data REA DY on e in b it 7 in d i c a t e s the d r iv e is un ab le to execu te th e comm an d (e .g ., th e door is op en ) . Th is b it is an inv erted copy o f the sign al from the cu r r en t ly :6 -W R IT E s e le c t e d PROTE CT d r iv e . 0R RECORD TYPE Durin g READ RECORD IS) th is b it rep resents b it 1 , in v e r t e d , o f t h e DA TA A DDRE SS M ARK data by te . 20 D u r i n g W R IT E o r h e a d m o v i n g o p e r a t i o n s , t h i s b it i s s e t to o n e kf th e d i s k e t t e in th e c u r r e n t ly s e l e c t e d d r iv e h a s b e e n w r i t e p r o t e c t e d . D5 - to H EA D DOWN D u r in g on e w h en h as 0R RE CO RD TYPE OR W R IT E FA U L T he a d m o v em en t c om m a n d s , th is b i t t h e h e a d i s d o w n a n d t h e s e t t in g is se t t im e e l ap s e d . Du rin g READ RECORD IS) , th is b it rep resen ts b it 0 , in v e r t e d , o f t h e DA TA A D D RE S S M A R K data by te . D u r in g W R IT E o p e r a t i o n s , t h i s b i t i s t h e W R I T E F A U L T s i g n a l f r o m t h e c u r r e n t ly a c op y o f se le c te d d r iv e . T h is b it D4 - N 0T is re se t a f t e r b e in g re ad . FO P N D A h igh in b it 4 in d ic ate s th e de s ired t rack / an d o r s e c t o r w e r e n o t v e r i f ie d . D u r in g R E A D A D D R E S S , a h i g h in b i t 4 i n d i c a t e s n o s e c t o r a d d r e s s f i e l d w as en coun t e re d . T h is b it is c le a re d a ft e r th e s t a tu s r e g i s te r i s r e a d . D5 - CRC ERROR A h i g h in b i t 5 in d i c a t e s t h e in t e r n a l C R C c h e c k d i d n o t a g r e e w i t h t h e d i s k e t t e 's C R C b y t e s . If b it 4 i s s e t , t h e C R C e r r o r o c u r r e d in a n a d d r e s s f i e l d ; o t h e r w i s e , i t in d i c a t e s a n e r r o r i n a d a t a f i e l d , 92 - TRA CK 00 0R D u r in g LO ST DATA h e a d M o v em en t in d i c a t e s t h e h e a d com m an d s , a from D u r in g th e data in bit 2 is p o s it ion e d ov e r T RA CK 0 0 (farth e st from th e cen ter ) . of TK00 on e c u r re n t ly t r an s f e r Th is sign al is a copy s e l e c te d d r iv e . c om m an d s , a on e in b it 2 indlcates that the comguter d1d not respond to DRQ w ith in one byte time (A .e ., 52 gseconds or 64 yseconds for 8'' or 5'' drives respective ly ) . LOST DATA As c le a re d a f t e r b e in g r e a d . 21 D 1 - IND EX 0R D RQ D u r in g h e a d m o v e m e n t c o m m a n d s , a o n e in b i t 1 in d i c a t e s t h a t t h e d i s k e t t e i n t h e c u r r e n t l y s e l e c t e d d r iv e i s p a s s in g t h e IN D E X o r b e g in n in g o f t h e t r a c k T h i s b i t i s a c o p y o f I P f r om t h e d r i v e , . D u r in g R E A D c o m m a n d s , a h i g h in b i t 2 in d i c a t e s th e 4F D C h a s a d a t a b y t e f r om th e d i sk r e a dy to b e T e a d a t p o r t 3 5H . T h i s b i t i s r e s e t a f t e r b e in g re ad . - , D u r in g W R IT E c o m m a n d s , a h i g h in b i t 2 in d i c a t e s 4 FD C n e e d s a d a t a b y t e f r om t h e co m p u t e r a t p o r t th e 3 5H . Th is b it D0 a - is reset after it is read . BP SY A h i g h i n b i t 0 i n d l c a t e s t h e 4 F D C i s e x e c u t in g d i s k c o m m a n d an d c a n n o t a c c e p t a n ew d i sk c o m m a n d y et (excep t a FORCE IN TERRUPT comm an d ; see descr ip t ion of FORCE THTER RU PT ) . 50 OU T D i sk C om m an d R e g i s t e r : T h e b it a s sign m en t v a r ie s w ith e ac c om m an , th e r e fo r e , e a ch c om m an d w i l l b e d is cu s se d s ep a r at e ly . SUM M A RY - - Command pl p-q p-y p-i pé pt pl p-q R E ST O R E SE E K ST E P S T E P IN STEP OUT 0 0 0 0 0 0 0 0 1 1 0 0 1 0 1 0 1 u u u 1 1 1 1 1 v v v v v T, r: r ) r l r l T a ro rc REA D R ECO RD IS ) W R ITE RECO RD IS ) 1 1 0 0 0 1 m m b b E E 0 a: 0 a: READ ADDRESS 1 1 0 0 0 1 0 J REA D T RA CK W R IT E T R A C K F O R C E IN T E R R U P T 1 1 1 1 1 1 1 1 0 0 1 1 0 0 la 1 1 lz 0 0 11 s 0 1 - - r c r o c 22 F lag s = 1 - =0 - v u m V e r i fy on la s t t r a c k U p d a t e tT a ck T e g is te r M u l t ip l e r e c o r d s V 0 v e r i fy No up date S in g l e t e c o r d b E f IBM b l o i k E n a b l e h e a d l o a d d e l ay N o sy n c h r o n i z a t i o n O th e f A s su K e h e a d i s d o w n Sy n c h r o n i z e t o A d d r e s s M a rk F ie ld s (8'' Stepp in g Rate ) (5,' Stepp in g Rate ) IN T E R R U P T C O N D IT ION S ; =0 =1 =2 =5 r Ar n 6 ms 12 m s 6 ms 12 m s 10 m s 20 m s 20 m s 40 m s Z 1& t) FB (DATA MA RK ) FA F9 F8 (DELETED DATA ) 1 a z7 1 T 2 = 1 W H EN WHEN I z= 1 I c= l IN D E X R EA D Y COM MA N D N0T IK JE D IA T E R EA D Y B E S C R I P T IO N RE ST OR E D p on r e c e ip t of th i T s c om m an d , t h e rack 00 (TR 00) inpu t is samp led T R 00 i If s a c t iv e 1ow in d ic a t in g th e R e a d W r it e h ea d is p o s i t ion e d ov e r t th r a ck 0 , e T r a c k R e g i s te r i s lo a d e d w ith ze ro e s an d E0J is se t If T R 0 0 i s n o t a c t iv e l ow , s t e p p in g p u l s e s a T e i s s u e d u n t i l t h e T R O O inp u t i s a c t iv a t e d ti A t th is m e , t h e T r a c k R e g i s t e r i s l o a d e d w i th z e r o e s an d E 0J i s s e t . . . . If the TR00 input does not go active 1ow after 255 stepp ing pulses t th e 4 F D C , e r m in a t e s o p e r a t l o n th , se t s E O J , an d se t s e S e e k e r r o r s t a tu s b i t th N o te th a t e R E S T O RE c om m an d i s e x e cu t e d a f t e r a R E SE T . A v e r i f i e a t i o n op e r a t i o n t a k . p la c e if th e V fl a g i es s SE E K Th is set . com m an d a s su m e s t h a t th e T r a c k R e g i s t e r c on t a in s th e t r a c k n u m b e r th e c of u r r en t p o s i t i on o f t h e R e a d W r i t e h e a d an d t h e D a t a R e g i s t e r c o n t a in s t h desired track numb e er . The 4FDC w ill u p d a t e t h e T r a c k R e g i s t e r an d i s s u e s t e p p in g p u l s e s i n t h e a p p r o p r i a t e 23 d i r e c t io n u n t i l t h e c o n t e n t s o f th e T r a ck R e g i st e t a T e e q u a l t o th e e o n t e n t s o f t h e D ata z egister (th e de sired track locat ion ) . A v e r i f i c a t ion op e r a t ion t ak e s p l a c e i f t h e V f l a g i s o n . E 0 J i s s e t a t th e c o m p le t io n o f th e c o m m a n d , ST E P D p o n r e c e ip t o f t h i s c o m m a n d , th e 4 F D C i s s u e s o n e s t e p p i n g p u l s e t o th e d i s k d T iv e . T h e s t e p p in g m o t o r d ir e c t i o n i s t h e s a m e a s in t h e p r e v l o u s s t e p c o m m an d . A f t e r a d e l a y d e t e r m in e d b y th e T IT C field , a veY ification takes glace if th e V f l a g i s on . If th e u f la g Is on , th e T r a c k R e g i s t e r is u p d a t e d . E 0J is s e t a t th e com p le t ion o f th e c om m an d . ST E P IN B p o n r e c e ip t o f t h i s c o m m a n d , t h e 4 F D C i s s u e s o n e s t ep p in g p u l s e in t h e d i r e c t i o n t o w a r d s t h e c en t e r o f t h e d i sk e t t e . lf th e u f l a g i s on , th e T r a ck R e g i s t e r i s in c t em en t e d b y o n e , A f t e r a d e l a y d e t e rm in e d b y t h e r lr n f i e l d , a v e r if ie a t ion t ak e s p la ce Af th e V f la g is on . E 0 J i s s e t a t th e c om p l e t ion o f th e STEP 0UT c om m an d . U p o n r e c e i p t o f th i s c om m an d , t h e 4 F D C i s su e s o n e s t e p p in g p u l s e in t h e d i r e c t i o n tow a rd s t rac k 0 . I f th e u f l a g i s o n , th e T r a c k R e g i s t e r i s d e c r e m e n t e d b y on e . A f t e r a d e l a y d e t e rm in e d b y th e r lr c f i e l d , a v e r i f i c a t io n t a k e s p l a c e i f th e V f l a g is the on . EOJ is se t at th e c om p le t ion of com m an d . T h e se f iv e com m an d s h av e an op t ion a l v e r i f i c a t io n f l a g . D u r in g v e r i f i c a t i o n , t h e f i t s t e n c o u n t e r e d ID f i e l d i s r e a d o f f t h e d i sk . T h e t r a c k a d d r e s s o f t h e 1D f i e l d i s t h e n eomp ared to the Track ke gister ; if there is a m atch and a v a l i d ID C R C , t h e v e r i f i c a t i o n i s c o m p l e t e , E 0 J i s s e t , a n d th e BU SY s t a tu s b it i s r e se t . If th e r e i s n o t a m atch bu t t h e r e i s v a l id I D C Z C , E 0 J i s s e t , t h e S e e k E r r o r s t a t u s b i t (Statu s b it 4) is set , and the BO SY sta tu s b it is teset . th e r e i s a m a t ch b u t n o t a v a l i d C R C , th e CRC e r ro r If sta tu s b it is set (Status b it 3) , and the next en countered ID field i s r e a d f t om th e d is k f o r t h e v e r i f i c a t i on o p e r a t i on . I f an ID f i e l d w i t h a v a l i d C R C c an n o t b e f o u n d a f t e r tw o r e v o lu t io n s o f th e d i sk , th e 4 FD C t e rm in at e s th e op e r a t io n , s e t s E O J , a n d s e ts r e co rd n ot foun d in th e s t a tu s t e g i s t e r . 24 The S T E P , S T E P - IN , a n d P PDATE flag (V ) . by on e S T E P -O V T c o m m a n d s c o n t a in an When U = 1 , the Ttack Re gister is up dated fo r e a c h s t ep . W h e n U = 0 , th e T r a c k R e g i s t e r i s n o t up d ate d . READ RECORD IS) Upon Teceip t of the Read command ? th e h e a d i s l o a d e d , th e BV SY s t a tu s b A t i s s e t ; an d w h e n a n ID f i e l d i s e n c o u n t e r e d th at h a s th e c o r r e c t t r a ck n u m b e r , co rrect s e c t o t n u m b e r , an d correc t CZC , th e d a t a f i e ld i s p r e s en t e d t o t h e c o m p u t e r . T h e D a t a A d d r e s s M a f k o f th e d a t a f i e l d m u s t b e f o u n d w i t h in 2 8 b y t e s o f t h e co t r e c t f ie l d ; i f n o t , th e R e c o r d N o t F o u n d s t a tu s b i t i s s e t an d th e op e r a t ion i s t e rm in a t e d . W h e n th e f ir s t ch a r a c t e r o r b y t e o f th e d a t a f ie ld h a s b e en sh ifted , D RQ is gen er ated . W h en th e n ex t b yte is accumu lated , an oth er DRQ is gene rated . Wh en th e next by te is late d y ano ther DRQ is generated . c omp u t e t h A s n o t re a d a c cum u - lf the th e p r ev io u s c o n t en t s o f t h e D a t a R e g i s t e r b e f o r e a n ew ch a r a ct er i s t r a n s f e r t e d , th a t ch a r a c t e r i s lo s t an d th e L o s t D a t a S t a t u s b i t i s s e t . Th is s e q u e n c e c o n t in u e s u n t i l t h e c o m p l e t e d a t a f i e l d h a s b e e n in p u t t e d t o t h e c o m p u t e r . I f t h e r e i s a C R C e t r o r a t th e en d o f th e d a t a f ie l d , t h e C R C e r r o r s t a t u s b i t i s set an d th e comm an d is term in ated (ev en if it is a mu ltip le reco td comm an d) . A t th e e n d o f th e R e a d op e t a t i o n y th e t y p e o f D a t a A d d r e s s M a r k e n c o u n t e r e d in t h e d a t a f i e l d i s r e c o r d e d in t h e S t a t u s ûeg ister (B its 5 an d 6 ) as shown be low : W R ITE RECORD IS) S t atu s S t a tu s D ata AM Bit 5 Bit 6 (l1EX ) 0 0 1 0 1 0 FB FA F9 1 1 F8 Up on rece ip t of th e W rite comm an d , th e h e a d i s lo a d e d an d th e B P S Y s t a tu s b it is se t . W h e n a n ID f ie l d i s e n c o u n t e r e d th a t h a s t h e c o r r e c t t r a c k n u m b e r , co r r e c t se c to r n um b e r y an d cor re c t CR C , a DRQ is generated . The 4FDC count s o ff 11 25 by te s from th e C R C f ie ld an d th e W r ite Gate (W G) ou tpu t is m ad e act iv e if th e DRQ is serv iced (i .e ., the D ata Register has been loaded by th e computer) . If DRQ h a s n o t b e en se rv lc e d , th e co m m an d i s t e rm in a t e d an d th e L o s t D a t a s t a t u s b i t is set , If the DRQ h as b een se rv iced , 5 ix by t e s o f ze r o e s a r e w r it t en on th e d isk . A t t h i's t i m e , t h e D a t a A d d r e s s M a rk is th en w r i t t e n on t h e d isk a s d e t e rm in e d b y t h e a la : f i e l d o f t h e c om m an d as sh o w n b e low : DA TA MARK XA #A (HEX ) 0 0 1 1 0 1 0 1 FB FA F9 F8 The 4FDC th e n C LO C K M A R K (HEX ) C7 C7 C7 C7 w r it e s th e data f ie ld and gen erates DRQ 'S to th e computer . the DRQ is n ot serv iced in t im e for If c o n t i n u o u s w r i t in g , t h e L o s t D a t a S t a t u s B i t i s s e t an d a b y t e o f ze ro e s is w r i t t en o n th e d isk . T h e c o m m a n d i s n o t t e rm in a t e d . A f te r th e l a s t d a t a b y t e h a s b e en w r i t te n o n t h e d i sk , t h e t w o -b y t e C R C i s c o m p u t e d in te rn a l ly :n d w r i t ten on th e d is k f o l low e d by one by te gap of log ic on es . The tw o comm an ds REA D RECORD IS) and W R ITE RE CORD IS) con tain a (b ) flag wh ich in con jun ction w ith the secto r len gth fiel d conten ts of the ID determ in es th e len gth (number of ch aracters) of the Data fie ld . For I BM 5 74 0 c om p a t ib i l it y , t h e b fla g sh o u l d equ a l 1 . The numbers of by tes in th e data field (se ctor) is th en 128 x 2n w h e r e n = 0 ,1 , 2 ,5 . Fo r b = 1 Se c to r L en g th N umb e r o f by tes F ield (hex ) in sector (dec im al) 00 01 128 256 02 51 2 05 1 0 24 26 When the b flag equ a ls zero , th e secto r leng th field (n ) m u l t ip l i e d b y 1 6 d e t e r m in e s t h e n u m b e r o f b y t e s in or as data f ie l d Fo r b = sh o w n th e sec to r b e low : 0 S e c t o r L en g th Numb er of by te s Fie ld (hex ) in s ector (d ec im a l) - - 01 02 05 04 16 52 48 64 * * * *. @ @ FF 00 4080 4096 Th ese tw o comm an ds a lso con tain a (m ) f 1ag w h ich determ in es if m u lt ip le records (sec tors ) are to be r e a d o r w r i t t en , d ep en d in g u p on th e c om m a n d . lf m = 0 , a s in g l e s e c t o r i s r e a d o r w r i t t e n an d E 0 J i s s e t a t t h e c o m p le t io n o f th e c om m an d , l f m = l m m u l t ip l e r e c o r d s a r e r e a d o r w r i t t e n w i t h t h e s e c t o r r e g i s t e r in t e r n a l l y u p d a t e d s o th a t a n a d d re ss ve r i fic a t ion c an o c cu r on th e n e x t r e c o r d . T h e 4 F D C w i l l c o n t in u e t o r e a d o r w r i t e m u l t ip l e r e c o r d s a n d u p d a t e th e se c t o r r e g is t e r u n t il th e se c t o r r e g i s t e r e x c e e d s th e n u m b e r o f s e c t o r s on th e t r ac k . A t t h i s p o in t t h e N O T y FO UN D a n d CR C e r ro r b it s a re se t , an d E OJ is se t . REA D A D D RES S U p o n r e c e ip t o f t h e R e a d A d d r e s s c om m an d , th e h e a d ls lo a d e d an d th e B U SY s t atu s b it is se t . T h e n e x t en co u n t e r ed ID f i e l d i s t h e n r e a d in f r o m t h e d i s k a n d th e s ix d a t a b y t e s o f t h e a re assem b led , 1D f ie ld DRQ is gen e ra ted f o r e ach b y te T h e s ix b y t e s o f th e f ie l d a r e sh ow n b e l ow : T RA C K A DD R 1 ID ZE R O E S SE C T O R ADDR SE CT O R LE N GT H CRC 1 CR C 2 2 5 4 5 6 A l th o u g h th e C R C t ran s fe r re d to th e ch ec k s fo r v a l i d ity ch a r a c te r s a re co m p u te r , th e 4 FD C an d th e C R C e r r o r s t a t u s b i t j.s s e t i f t h e r e i s a C R C e r r o r T h e S e c t o r A d d r e s s o f th e ID f i e l d i s written in to the sector reyister . en d o f th e op e r a t ion , E 0 J B U S Y s t a tu s b it i s r e se t . as . set At the an d the - 27 REA D T RA C K U p o n r e c e ip t o f t h e R e a d T r a c k c o m m an d , t h e h e a d i s l o a d e d a n d t h e B U S Y s t a tu s b it i s se t . R e a d in g s t a r t s w i th t h e l e a d in g e d g e o f th e f i r s t e n c o u n t e r e d in d e x m a r k a n d c o n t in u e s u n t i l th e n e x t in d e x p u l s e , A s e a ch b y t e i s a s s em b l e d , it i s t r an s fe r re d t o th e D a t a R e g is t e r an d th e D a t a R e q u e s t i s g en e r a t e d fo r e a ch b y te . N o C R C c h e c k in g i s p e r f o r m e d . G a p s a r e in c l u d e d i B t h e in p u t d a t a stream . If b it 0 (S ) o f th e comm an d is a 0 , th e a c cu m u la t i on o f b y t e s i s sy n c h r on i ze d t o e a c h A d d r e s s M a r k en coun tered . U p on com p le t ion o f th e c o m m an d , E 0 J i s s e t . W R IT E TRACK U p o n r e c e ip t o f t h e W r i t e T r a c k c om m an d , th e h e a d i s lo a d e d an d th e BU SY s t a tu s b i t is s e t . W r i t in g s t a r t s w i t h t h e l e a d in g e d g e o f t h e f i t s t e n c o u n t e r e d in d e x p u l s e an d c o n t in u e s u n t i l t h e n e x t in dex pulse at wh ich time the in terrup t i s a c t iv a t e d . Th e D ata Reque st is a c t i v a t e d im m e d i a t e l y u p o n r e c e i v in g t h e c o m m a n d , b u t w r i t in g w i l l n o t s t a r t u n t i l a f t e r t h e f i r s t b y t e h a s b e en l o a d e d in t o th e D a t a R e g i s t e r . If th e D at a R e g i s te r h a s n o t b e e n l o a d e d b y t h e t im e t h e in d e x p u l se is en c ou n t e r e d , th e op e r a t io n i s t e r m i n a t e d m a k in g t h e d e v i c e N o t B u s y , th e L o s t D a t a s t a tu s b it i s se t , an d E 0 J is set , I f a b y t e i s n o t p r e s e n t in t h e D a ta R e g i s te r w h en n e ed e d , a by t e o f ze r o e s is su b s t itu t e d . A d d r e s s M a rk s an d C R C ch a r a c t e r s a r e w r it t en on t h e d i sk b y d e t e c t in g c e r t a i n d a t a b y t e p a t t e r n s i n t h e o u t g o in g d a t a s t r e a m a s s h o w n in th e t a b l e b e l o w , T h e CR C g en e ra to r is in it ia l i z e d w h e n an y d a t a b y t e f r o m F 8 t o F E is a b o u t t o b e w r i t t e n . CON T R O L BY T E S F 0 R IN I T IA L I Z A T I O N DA TA PA T TE RN (HEX ) CLOCK INTERPRETA T ION F7 W r it e CRC Ch ar . F8 Data F9 FA D a t a A d d re s s M a rk D ata A d d re s s M a rk A ddre s M ark M ARK (HEX ) FF C7 C7 C7 28 DA TA PA TT E RN CLOCK M AR K (HE X ) INTERPRETAT ION (HEX ) FB FC D a t a A d d r e s s M a rk ln d e x A d d r e s s M a r k C7 D7 FD FE Sp a r e ID A d d r e s s M a r k C7 Th e W r ite T r ack c om m an d w il l n o t e x c e cu t e i f SW 4 i s 0N . N o t e th a t o n e P a t t e rn gen e r a t e s 2 CR C Ch ar a ct e r s . FO R CE IN T E R R U P T F7 T h i s c o m m an d c a n b e l o a d e d in t o t h e c o m m a n d r e g i s t e r a t a n y t im e . If th e r e i s a cu r r en t c om m an d u n d e r e x ec u t ion (BU SY statu s b it set ) , th e comm an d w ill be t e r m in a t e d an d E0J w ill be set w h en t h e c o n d i t i o n s p e c i f i e d i n th e 1 : t h r o u g h I a f ie ld is d e te c t e d z T h e in t e r r u p t c on d it ion s a r e sh ow n b e low : 10 1) 12 1a = N o t - R e a d y -T o - R e a d y T r a n s i t i o n = R e a d y - T o -N o t - R e a d y T r a n s i t i o n = E v e r y In d e x P u l s e = Im m e d i a t e I n t e r r u p t If I a - I c = 0 , th e c om m an d w i l l b e t e rm in a t e d b u t E 0 J w i l l n o t b e s e t . The F O R C E IN T E R R U P T c o m m a n d s a b o v e m u s t b e c l e a r e d in t h i s m a n n e r b e f o r e t h e 4 F D C i s g iv e n i t s n e x t c o m m a n d . 31 IN /OUT T rack Re g iste r : Th is re g ister h o ld s th e t rack num er o t e cu rren t Read/W rite head p o sit ion . It is in c r e m e n t e d b y on e ev e ry t im e th e head is stepped in (tow ards track 76 ) and decremented by one when the head is stepp ed out (tow ards track 00) . Th e con ten ts of th e reg ister are comp ared w i t h t h e r e c o r d e d t r a c k n u m b e r in t h e ID f i e l d d u r in g d i s k R e a d , W r i t e , a n d V e r i f y o p e r a t i o n s . T h i s r e g i s t e r sh ou ld n o t b e lo ad e d w h e n t h e 4 FD C i s b u sy . 32 IN /OU T Se cto r Reg ister : Th is reg iste r h o ld s th e add re ss o th e d e s i r e se c to r p o s it ion . Th e con ten t s o f th e r e g i s t e r a r e c o m p a r e d w i t h t h e r e c o r d e d s e c t o r n u m b e r in t h e ID f i e l d d u r in g d i s k R e a d o r W r ite op e r a t ion s . T h i s r e g i s t e r sh o u l d n o t b e l o a d e d w h e n t h e d e v i c e i s b u sy . 29 55 D âIA Reyister : IN /OU T Th is register is used as a hold - . in g r e g i s t e r d u r in g D i s k R e a d a n d W r i t e o p e t a t i o n s . ln D i s k R e a d o p e r a t i o n s , t h e a s s e m b l e d d a t a b y t e i s t r an s f e r r e d in p a r a l l e l t o t h e D a t a R e g i s t e r fro m th e D a t a Sh i ft R e g is te r . ln D i s k W r i t e o p e r a t i o n s , in f o r m a t i o n i s t r a n s f e r r e d in p a r a l l e l f r om th e D a t a R e g i st e r to th e D a t a Sh i ft R e g i s t e r . 54 IN D i sk Flags : DRQ B00T T h i s p o r t p T ov id e s HEA DLOAD X X fo u r X s i gn a l s . X E0J 5 7 -DRQ A h i g h in b i t 7 in d i c a t e s t h e 4 F D C h a s a b y t e f r o m t h e d i s k o r n e e d s a b y t e f o r t h e d i sk a c c o r d in g t o th e c u r r e n t o p e r a t io n . D6 -B O O T A 1ow A h i gh in b it 6 in d i c a t e s th a t SW 5 is se t to BOOT . D5 b it 6 in d i c a t e s SW 5 is set to M ON . -H E A D L O A D A r e n t ly o n e in b i t 5 i n d i c a t e s t h e se l e c t e d d r iv e i s l o a d e d . A D 4 -D 1 D0 in ze r o in b it 5 in d i c a t e s head of th e th e h e ad h a s u n lo ad e d . -u n a s s i g n e d -E O J A one in b it 0 in d i c a t e s th e c om m an d h a s fin ish ed . (En d o f job ) 34 0U T D is k cu r - C on tro l : P.1 PA PA P-i PA PJ. P1 P-t AUTO W A IT X M OTOR 0N MAX I D S4 DS3 DS2 DS1 30 1)7 -A U T O W A IT A on e in b i t s e v e n p u t s t h e 4 FD C in t o A u to W a i t m ode wh ich means th at sub sequent Teading of lnput Port of 54H w ill h o ld th r e e the C P IJ in a W A IT state un t ll on e t h in g s h ap p e n : a) Th e 4FDC issue s a DRQ (th is is the norm al u se of AIJTO WA IT ) b) Th e 4FDC issues E0J - th is term in ate s th e AUTO WA IT cond it ion (the norm a l m ethod o f term in ation ) . c) There is a h ardw are RE SET . 1)6 -u n a s s i g n e d 1)5 -M o t o r A a11 to 0n on e d i sk in b it 5 th e m o t o r -o n s ign a l to d r iv e s - A z e 'r o in a11 d isk clr iv e s . T h i s b it 1)4 a c t iv a t e s b it is S d e a c t iv a t e s set by th e m o to r - on s ign a l R E SE T - -M A X I A d i sk on e in b it 4 co n d it ion s th e 4FD C fo r an 8 '' a 5 '' d r iv e - A ze ro in b it 4 c on d it ion s th e 4 FD C fo r disk drive (M 1n i) . T h i s b it D 5 -D 0 - D R IV E is set by R E SE T . SE LE CT A h i gh in b i t s 5 t h r o u gh 0 s e l e c t s t h e c o r r e s p o n d i n g d i s k d r i v e f o r a 1 1 fu r t h e r o p e r a t i o n s . O n ly o n e d r i v e s h o u l d b e s e l e c t e d a t a g iv e n t im e R E S E T d e s e l e c t s a 1 1 d r iv e s . 40 0UT Ban k Se le c t ; O u tp u t t ln g any by te to port 4 0H T fW b le th e IK R0M on th e 4FD C i f SW 2 i.s on R0M m ay be r e -e n ab l e d b y R E SET . w i11 Th e 51 CHAPTER Th e 4EDC 4 : IN T E R F A C E appe a r s an d 15 I/ O p o r t s . rup t s an d on C H A R A C T E R I S T IC S th e S-l00 bus as a IK S-100 m em o ry ca rd Th e 4F DC is c ap ab le o f gen e r a t in g in t e r - re sp o n d in g o n a p r io r i t i ze d b asis to th e in t e r r u p t a ck n o w le d g e cy c le (N .B - c o o s d o e s n o t u s e th e in te r r up t c ap ab i l i ty o f th e b o a r d .) D a t a e x ch a n ge fo r tn e d i sk an d se r ia l I/ O is p ro gr amm e d , n o t v ia d ir e c t m em o ry ac ce s s (DM A ) . Th is requires w a it sta te s a m i n im u m CPU speed of 2 mHz an d no m em o r y (a t 2m H z ) in th e b u f fe r m e m o r y . The Boo tstrap/Mo n itor ROM is addre ssed a t C 000-C 3FFH . Th is ad d r e s s m a y be jum pers at IC 44 . c h an ged by c u t t in g tr ace s an d in se r t in g Ho ld acknow ledge w ill tem porarily d isab le th e R OM . A t 4m H z , th e 4F D C in se r t s one w a i t s ta te o n M l (in s t ru c t io n fe t c h ) c y c le s fo r Z 8 0 e o m p a t ib i l it y . T h e r e a r e n o w a i t s t a t e s a t 2m H z . W h e n sw i t c h o n e i s o n , t h e fe a te d an d th e 4F D C o c e up ie s n o ad d r e s s sp a c e in W h e n sw i t c h 2 i s o n , t h e R O M i s d i s a b l e d a s s o o n ROM is d e m emo ry a s a b y te . (an y b y te ) i s w r it ten to o u tp u t p o r t 4 0H , th e b an k se le c t port . P Th e ROM is re -en ab led by a hardw are RE SET . The ser ia l I/ O ch ann e l re qu ire s 1 0 I/O add re sse s . C DO S requ ire s th e se to star t a t I/ O ad dre ss 0 0 , th e w ay th e 4FDC is or sh ipp e d . T h e s t a r t i n g a d d r e s s m a y c h an g e a t 1 0 2 0 , 5 0 y 6 0 , y 7 0 H b y c u t t i n g t h e t r a c e a t t h e ''0 '' o u t p u t o f I C 7 a n d m o v in g it to an o th e r o u tp u t p in . a syn chronou s be cau se it u se s th e T h e se r ia l I/ O ch ann e l i s o n -b o a rd c lock When . one of th e ser ia l I/ O ch ann e l 's p o rt s is add re ssed by th e CPU , th e 4F DC pulls down PRDY n i ze s w i t h t h e C P U and h o ld s (u p t o it d ow n until of 30H , a ltho u gh t r a c e a t th e tw o c a se s in 4F DC synchro - l u se c o) Th e d i sk I/O p o r t s a re sy n c h ro n o u s . add re ss th e th is m ay be C D O S a s sum e s a b a se c h an ge d by c u t t in g ''3 '' o u t p u t o f I C 7 a s e x p l a i n e d a b o v e w h ich th e 4F D C w i l l c r e a t e w a it st a t e s e the There fo r ar e the d i sk I/ O p o r t s : 1 ) i f th e p o r t s 30 - 3 3H a re re ad a t 4 m H z th e re w ill be one wait state added fo r th e F D 17 7l data to s ta b i l i ze , an d 2) i f th e A u to -W a i t m o d e h a s b e e n se le c te d an in d e f in it e num b e r o f w a its w il l b e p o r t 34H . Th e C P U w i ll a d d e d to r e ad o r w r i te o p e r a t io n s o n s t a y in a W A I T s ta te u n t i l th e 4 F D C i s su e s a D a t a R e q u e st or an E n d o f J ob s ign a l (o r th e r e i s a h a r d w a re RE SE T ) . T h i s m o d e i s u se d w h e n r e ad in g o r w r i t in g 8 f' d i a k e t t e s w i t h a In te r fa c e 2m H z C P U Ch ar acter istic s Th e 4FD C p ro v ide s in te r fa c e . For R5-232 a s fo l lo w s ) - Se r ia l Ch ann e l 5 0 th R5-2 32 and 20 m h cu rren t c o n n e c t th r e e w i r e s fro m y o u r lo op t e rm in a l 32 4F D C RS-232 J4 Som e such te rm in a l (i oe . C R T ) P in 7 S i in a l g r o u n d (n o t c h a s s i s ) p in 3 Re c e iv e r d a t a (fo r d i sp la y ) P in 2 T r an sm i t te r d a t a te rm in a l s m ay r e q u i r e ad d i t io n a l m o d em a s C le a r t o Se n d v D a t a Se t R e a d y , D a t a e tc - Th e se For m ay 20 m a be w ired t e le ty p e to J4 p in 23 (k ey b o a rd ) con trol C ar r ie r o f th e in te r fac e r m ak e th e sign als De te c t , 4FDC - fo l low in g co nnec - tio n s : 4F DC ASR33 J4 (r e a r t e r m in a l b lo c k ) p in 25 t e rm in a l 6 (p r i n E e r c u r r e n t o u t ) p in 24 t e r m in a l 3 t k e y b o â r d c u r r e n t o u t ) p in 2 3 - t e r m i n a l 7 tp r in t e r c u r r e n t in ) p in 1 7 t e rm in a l 4 tk ê y b o a r d cu r r en t in ) In t e r f ac e Th e 4F DC Ch ar acter istics d r iv e s J2 and - 8 '' a n d J 3 , th e 5 '' D i s k D isk C o n n e c to r s , in p a r a l le l th ro u g h se p a r a te D r iv e D r iv e s Sign a l C ab le se t p o f T T L b u s d r iv e r s o T h e S i g n a l c a b l e s s h o u l d b e t e r m i n a t e d (1 5 0 o h m r e s i s t o r s t o + 5 v o l t s ) a t t h e e n d o f t h e c ab le o n ly I f m o r e t h a n o n e d r iv e r p e r cab le up s . a ted i s u s e d , o n ly t h e l a s t d r iv e S ign a l s from th e d r iv e s b a ck on th e 4F DC w ith O u tp u t s fr om th e 15 0 oh m 4F D C : on tb thê th e c ab le sh o u ld u se p u l l c b n t r o l le r a r e t e rm in - p u l lu p s . (a 1 1 a c t iv e lo w 0 .6 v o l t s ) DSl DS2 Th e se a re th e se le ct s ign a l DS 3 ab lè its da ta and statu s drive rs and lo ad the read/ DS4 w r i te he ad . fo u r d r iv e s e l e c t s i g n a l s . W h e n a d r iv e i s ac t iv e t h e se l e c t e d d r iv e sh o u ld e n - A 1 1 o th e r d r iv e s s h o u l d u n t i l se l e c t e d . ign o re sign als W h ë n D R IV E S E L E C T i i f ir st a s se r te d # th e 4F DC w a it s a fix e d L OA D b e fo r e r e a d in g o r a m o u n t o f t im e fo r t h e w r i t in g th e d i sk e t te . head Th is to t im e d e l a y i s 4 8 m s f o r 8 '' d r i v e s a n d 7 2 nhs f o r 5 '' d r i v e s Th e d e lay m ay b e ch an ged b y r ew ir in g IC 5 3 . T h e d e lay is 8 m illisecond s tim e s (l6 - d elay jumpet v altte) a s sh ow n on th e fo l low in g p a g e - 33 IC 2 ''0 '' (GN D ) I5 0 ''l '' (+ 5 ) 11 14 3 6 O o 8 l6 4 2 o o 1 1 f) O 1 1 jj !1 Th i s line go e s a c t iv e (7 1 jj 11 De l ay ST E P 1 0 13 De lay 1 ow fo r 1 6 m icro sec o n d s to m o v e t h e h e a d o f th e se le c t e d d r iv e in th e d i r e c t io n sp e c i f ie d b y o u t p u t D I R C . Fo r m u l t ip le ste p s , th e s te p p in g r a t e i s d e t e r m i n e d b y t h e fo r m a t o f t h e c o m m a n d g i v e n to th e 4 F D C a n d w i l l b e 6 , 1 0 o r 20 m i l l i s e c o n d s p e r s te p the fo r l a r g e Persc i f lo p p ie s 2 7 7 , in w h ic h (e x c e p t v o i c e c o i l ty p e s l ik e c a se it is about 4 0 0 m ic r o - se c o n d s p e r s t e p ) o r 1 2 , 2 0 o r 4 0 m i l l i sec o n d s p e r s t e p fo r s m a l l f l o p p i e s . Th e 4F DC w il l w a it o ne step p i n g p e r i o d a f t e r t h e l a s t s t e p fo r t h e H e a d t o s e t t l e b e fo r e a t t e m p t i n g t o r e a d o r w r i t e t h e d i s k e t t e . D IRC W h e n th i s l in e i s a s se r te d (1 o w ) p u l s e s o n t h e S T E P l i n e sh o u l d c a u s e t h e h e a d o f t h e s e l e c t e d d r i v e t o a d v a n c e one t r a c k p e r s t e p t o w a r d s t h e c e n t e r o f t h e d i sk e t te . I f D IR C i s h ig h , p u l se s o n t h e S T E P l in e sh o u ld c a u se t h e h e a d o f t h e s e l e c t e d d r iv e t o r e t r e a t o n t r a c k p e r s te p tow a r d s th e o u te r e d g e o f th e d i sk e t te (to w a r d s T r a c k 0 0 .) Mo to r On Th is sign al turn s on th e motors of a1l d r iv e s wh en W h e n h i g h i t t u r n s o f f t h e m o t o r s o f f a 1 1 d r iv e s e qu ipp e d l a signal go e s 1ow to e n ab le d isk e t te w r ite low . (s o W R IT E Th is opera- GA T E t io n s . W R IT E DATA T h i s s i g n a l c o n t a in s t h e in t e rm in g l e d c l o c k a n d d a t a p u l sœ t o b e w r it ten o n th e d i sk e t t e . P u l se w id th i s 5 0 0 n a n o s e c o n d s f o r 8 '' d r i v e s , l m i c r o s e c o n d f o r 5 '' d r iv e s . RE ST O RE Th is sign a l reque sts re turn to T RACK 00 . C DO S d r ive r s . th e h e a d o f t h e s e l e c t e d d r iv e T h i s s i g n a l i s n o t u sed b y th e to 34 EJECT Th is signa l LEFT to e ject its le ft h and d iskette . EJECT Th is RIGHT to e jec t its r igh t h and d iskette . s ign a l In p u t s to r eque sts reque sts th e 4 F D C th e th e curren tly c u r r e n t ly (a 1 l a c t iv e 1o w se le c te d Persc i 277 se le c t e d Pe r sc i 277 0 .6 v o l t s ) IN D E X T h i s l i n e sh o u ld g o 1o w fo r a t l e a s t p e r r e v o lu t io n o f t h e d i s k e t t e , TRACK 00 Th is signa l d r iv e i s o n sh o u ld go 1ow t r a c k 0 0 , th e an d s t a y lo w w h i le o u t e rm o s t t r a c k . READY Th is sh o u l d w h en s ign a l (i .e . d o o r be 1ow i s c lo s e d , m o to r th e 10 d i sk u se c o n d s d r iv e sp e e d u p , e t c . ) once th e se le c te d is o p e r ab le Th e 4F DC w i l l a lw a y s i n i t i a t e a c o m m a n d r e g a r d l e s s o f t h e s t a t e o f r e a d y ; th e p u r p o s e o f th e s i g n a l i s fo r d e t e c t in g d i s k c h a n g e o p e r a t i o n s u s in g t h e F o r c e I n t e r r u p t c o m m a n d W R IT E P RO TE C T T h i s s ign a l go e s 1ow i f a w r ite -p ro te c ted in th e c u r r e n t ly se le c te d d r iv e . d i sk e t te REA D DATA T h i s s i gn a l i s co m p o s it e c lo c k a n d d a t a P u l s e s f r om 5 '' d r i v e . T h e l i n e sh o u l d g o 1 o w fo r 1 m i c r o s e c o n d e a c h f l u x r e v e r s a l 'o n t h e s u r f a c e o f t h e d i s k e t t e is the fo r . SEP DA TA T h i s s i g n a l co n t a in s t h e d a ta (se p a r a t e d fr o m t h e e lo ck p u l s e s ) f r o m t h e c u r r e n t l y se l e c t e d & ''' d r iv e . T h e p u l s e sho u ld S EP C LK be 1ow fo r 2 5 0 n a n o se co n d s . T h i s s i gn a l co n t a in s th e c lo ck st re am (sl RqwAa te d fr om t h e d a t a p u l se s ) f ro m th e c u r r e n t l y s e le c t e d 8 '' d r iv e Th e p u l se s sh o u ld be a c t iv e 1ow fo r 250 . nanoseco nd s , S EEK COM PLETE T h is signal sh o u ld go 1ow when the v o ic e c o i l d r iv e has p o s it io n e; th e re ad/w r ite h e ad ov e r th e d e s ired t r ack . Th i s signa l to vo ic e is co il g a t e d w i t h d r iv e d rive s l ik e th e se le c t an d Per sc i 277 . a p p l i e s o n ly . k ;: R ' -r c q r c ox r f xto .:o œ .:œ < 2 6 . J , c -m73 4oao ca4 c -m- 7 . a+ tas oNp jc aa tu, x D + sv 7 ,a K 27 = 1 7 4 16 1 55 1 s !s: 1t:5 3 r: sz.m Raz t & >- 1 Q c14 74ksa4o ,c25 e lca: 7406 74 = . = 74164 <32 + = 74k c*: .04 < t,s : < m y w ,'- 34 ! # 5 ; p- - INTER z !cI3 74t: 2 4 1 4 . Q %z 4Msssol > & 1f23 6 74 2 0 . ag e - w 4 ' pcas gyqsa, A < #Q :47 x u .* 7 *(7=JD 74:s:: Icsoc '-o m /4sa73 M * % jrj- t3o . < - cw a y R.a ,x rX :t<= œ - ; M % Q *'. ;3' ./!ca4741.:86 1f: 494u5r 7r 74k ,515/cXN . : o x o Q '! W ' /'6.77= 3 c rr mo c;o c 17'1-1 & 1@ -0 xz * 1E33 74S373 'f 1C48 S66 X < 16 3 2 74 1 $ 0 4 1E : 4 74 L: 174 'Q C4 4 . < Q 3* n 0 - E . 7* al : =-. = ?' t!z + lc * 7 t,:cuvio o goa 74 t s:l w x hcxut- M --D t*a . m >: x R o e f.tl QJ xx 'Q m - r #'lc9 7436: 1E13 js m :!: . Q t c (..-, . , < w- : * f:zs u 7452 I clejcm o 74367 >' y4g6y . k .. < . e jc , s o 8 < c '--j m t jl %ô x s - - Ic4s ; j$ ; jj y jy x jtgw : /1 m . > . 0 L. ac. so 49 gjcqg4. t1+1j = zlk ç:ysog +j ljjja >-z4o yw, murlju m ;:t1 O @. ;L E -I 4 Nl C .1 ;XI 'f #c 6 7 4 3 6 8 < 'f l(22 o 74 k G 1O Ic 5 74 36 7 ' m îm o Z t yt )t? 74 :)s v n e.x< . e -- N N l xx h hy -- ax N x sx N x .N w. . y . *' ! q M ) ' N +>. Ns # A Ql N x . N f > . ,# < l t 4 x f? j ''ï ( r 1 z' - w . N : ê /; X .., N x - JU M P E R p u u G CU T M UX ST RA P CUT FRA M E GROUN D 39 F in a l ly , lo c a t e th e sp a d e 1u g g ro un d o n th e re ar c h a s s i s w i th a w h ite w ir e u n d e r i t . R e m o v e th e sp ad e 1 u g , d i s co n n e c t th e w h it e w ir e , a n d r e p la c e th e sp ad e lu g . T a p e Eh e w h it e w ir e (o r c u t i t o f f ) ; i t i s n o l o n g e r n e e d e d . T h i s i so l a t e s c h a s s i s g round f rom lo gic ground . (See F igure 6 -1 for deta ils) . In i t i a l Ch e ck -o u t Se t th e M ON sw it c h 3 , to th e M ON p o s it io n (o f f ) ; th e RE s id e n t sw i t c h , sw i t c h 2 , to R E S p o s i t i o n (o f f ) ; an d th e R OM e n a b l e sw i t c h to R O M p o s it io n (o f f ) . V e r i fy th a t y o u r c o m p u te r h a s a p ro c e s so r an d a t le a st IK o f r e a d /w r i te m em o ry ad dr e s sed an yw h e r e b u t C 0 0 0 (the Mon ito r/Boo t co ld st art en t ry po in t ) . S in c e t h e M O N sw i t ch i s s e l e c t e d . t h e M o n i t o r p r o g r am w i l l b e e x c u t e d in s t e a d o f t h e B o o t s t r ap lo ade r P r e s s ''C a r r i a g e R e t u r n '' o n y o u r t e rm in a l u n t i l t h e m o n i t o r s i g n o n m e s s a g e a p p e a r s i n d i c a , t i n g th a t t h e m o n i t o r h a s s u c c e s s f u l l y d e t e r m in e d t h e t e rm in a l s b aud r ate . Le ga l B aud ra te s are 110 , 1 5 0 , 300 , 1 200 , 24 00 , 4 800 , 9 6 0 0 , a n d 1 9 ,2 0 0 . . In s e r t a d i sk e t t e in y o u r D r i v e A a n d fo rm a n c e b y c a l i b r a t i n g t h e d r iv e , se e k in g in g t h e f i r s t se c to r a s d e t a i le d b e low : ;A ; A ;R D A JS 2 80 1 80 S To b r in g Th is re sto re s See k tr ack Re a d s in t o up the th e 2 8 0H C romem co h e ad th e D i sk v e r i fy t h e d r iv e p e r ou t 2 track s y and r e ad - if la st 8 ''7 t y p e A ; ; ; fo r s ''d r i v e se c to r O p e r a t in g Sy stem , se t up your comp u ter w ith 32 k iloby te s o f re ad/w r ite m em ory add re ssed from 0 0 00- 7FF FH . T h i s m e m o r y m u s t b e f u l l s p e e d (4 5 0 n s a c e s s t im e m a x im u m ) i f y o u a r e r u n n in g a n 8 '' d i s k d r iv e a n d h a v e a 2m H z p r o c e s so r . W e re com m e n d e i the r th e 4K Z st a t ic m e m o r y c a r d s f o r r e l i a b l e o p e r a t i o n a t b 0 t h h ave (C P U a C rom em co ZP U , s e t it fo r 2 or 4 mHz m em o ry o r l 6K Z dy n am ic 2 and 4 m H z If you o p e r a t io n a s d e s i r e d . sp e e d d o e s n o t a f fe c t d i sk p e r fo r m a n c e ) an d s e t t h e p ow e r - on - jum p addre ss to ''C 0 00 '' (i -e . A 1 5=A 14= 1 ) . On the 4FDC se t the M ON sw i tch r sw i t ch 3 , to th e B O O T p o s i t io n (o n ) an d th e R E s id e n t sw i t c h , sw l t ch 2 , to t h e B A N K p o s i t io n (o n ) . Pow e r up th e sy s t e m an d e x e c u te C 0 0 0 H T h e h e ad w il l lo a d o n d r iv e A a s th e B o o t s t r a p p r o g r am in t h e R O M r e ad s in s e c t o r l o f tr a c k 0 0 , a n d tr a n s fe r s p r o g r a m c o n tr o l to C D O S (th , a n d ''d e b o o t s '' e R O M d i s a b l e s it s e l f , le a v in g ad d r e s s C 0 0 0 - C 3F F H f r e e fo r th e . sy s t e m un til i f n e ce s s ary ) . th e CDOS s igno n Pre ss m e ssa ge ''C a r r i a ge R e t u rn '' o n y o u r t e r m in a l appears , s u c c e s s f u l l y d e t e r m i n e d t h e t e r m i n a l 's l o ad a g a in a s m o r e o f th e C D O S p r o g r am in d ic a t in g th a t C D O S b a ud r a te Th e h e ad i s re ad in to m em o r y . . com m and D IR w il l list th e n am e s o f th e f i le s o n th e d i sk . has w ill The 40 CHA PTE R Pow er 7: T H E O RY OF O P E R A T IO N Su p p l ie s T h e u n r e g u l a t e d b u s p ow e r l in e s a r e c o n v e r t e d t o T e g u l a t e d su p p l i e s o f + 5 , - 5 , a n d + 1 2 v o l t s b y IC s 4 0 , 1 S , an d 3 9 r e sp e c t iv e ly . T h e 4 F D C r e q u i r e s 1 .0 A a t + 8 u n r e g u l a t e d , 0 .1 0 0 A a t + 1 8 u n r e g u l a t e d , a n d 0 .1 0 0 A a t - 1 8 u n r e g u l a t e d . Addre ss Decode The 4FDC d e co d es a d d r e s s an d s ta tu s s ign a l s on th e bu s to fîn d th e fo llow ihg condition s : 1) M em ory read cy cle s in th e address ran ge C 000 -C 5FFH > 2) Inpu t/ou tpu t re feren ce s in th e address ran ge 00 -0 9 , 5) Inpu t/ou tpu t re feren ce s in the add re ss ran ge 50 -34H , and 4 ) Ou tpu t re feren ce s to p ort 40H , ln case 1 , IC 5 0P 9 w ill go 1o w , e n a b l in g th e IK p rom In c a s e 2 , t h e a d d r e s s d e c o d i n g i s d o n e i n F ir s t , th e b a s e a dd r e s s is d e c o d e d b y IC 7 t h e n , i s d e t e rm in e d b y 1 C 2 5 . P in I S o f I C 7 g o e s 1 o w in t h e r a n g e o f 0 0 - 0 F H . tw o stage s 1C 5 1 - . th e o ff s e t fo r a d d r e s s e s In c a s e 3 , 1C 7P l 2 g o e s 1 ow w h e n t h e a d d r e s s b a s e 3 0 - 5 F H is d e te c te d . F u r t h e r d e c o d in g i s p e r f o rm e d b y 1 C 1 1 's ad dre ss inpu t s an d by the gat ing in th e read/w r ite c ircu its of IC 56 In p u t o r o u t p u t T e f e r e n c e s t o p o r t h i gh l e v e l a t 1 C 2 2P 5 . 5 4H a r e s i gn a l le d b y a . In c a s e 4 , I C 7 P 1 1 g o e s 1 o w f o r a d d r e s s b a s e 4 0 - 4 F H l C 8 P 1 1 g o e s 1 o w f o r o u tp u t s w i t h a n o f f s e t o f 0 . 1C 2 9 t h u s c l o c k in g , o n o u tp u t r e fe r en c e s t o p o r t 4 0H . Da ta Bu s T h e 4 F D C h a s a th re e s t a t e b i d i r e c t l o n a l i n t e r n a l d a t a a bu s . I t i s c o u p l e d t o t h e D a t a ln a n d D a t a 0 u t b u s e s o n t h e S -1 0 0 bu s th r ou gh la t c h IC s 3 5 an d 5 0 T h e re a r e fou r c a se s o f o p e r a t i o n d e t e rm in e d b y t h e p a r t i c u l a r 4 F D C f u n c t i o n . b e in g addressed . 41 C a s e 1 , M em o r y R e a d : W h e n 1C 50 P 9 g o e s 1 o w s e l e c t in g t h e 2 7 0 8 , d a t a a p p e a r s a t t h e i n p u t s o f e x c l u s i v e -o r g a t e s I C s 3 4 nd 35 . T h e c o m m o n in p u t t o t h e s e g a t e s i.s h e l d 1 o w b y a siyn al f rom IC 7 , so data pa sses th rou gh the ex -ors w ith ou t b e in g in v e r t e d . N e x t , f ou r b i t s a r e p ' r e s en t e d t o m u l t ip l e x e 'r 1C 4 9 . T h e s e l e c t p in I C 4 9 P 1 i s h e l d h i g h b y a s i g n a l f r o m 1C 2 3 . s o d a t a p a s s e s s t r a i gh t th r o u gh t h e m u l t i p l e x e ' r. E i gh t b i t s o f da t a n ow a r e p r e s en t e d t o th e l a t c h lC 5 0 . T he g a t e o f t h e l a t ch , IC S O P I I , i s h e l d h i gh b y I C 2 0P 8 a s l o n g a s t h e R0M i s en ab l e d , so d a t a p a s s e s th ro u gh th e l a t c h . T h e th r e e s t a t e o u tp u t d r i v e r s o f t h e l a t c h a r e e n a b l e d d u r in g P D B IN by a 1 ow at IC 1 9P 6 . Case 2 , Input/output references in the range 00-09H : W h en t h e T M S 5 5 0 1 1 C 1 2 a.s a d d r e s s e d , t h e 4 F D C e m u l a t e s a n I/0 cyc le (M 3) . Th is is necessary to gen erate strob ed statu s b it s an d to in su re th e co rrec t re ad /w r ite t im in g . b e g in s w h e n 8080 1C 2 5P 5 go e s 1ow p r e s e n t in g in p u t s o f th e f i r s t s e c t ion o f IC 5 . a h i gh to Th e cy cle th e J K T h is s e c t ion o f lC 3 i s c l o c k e d b y t h e f a l l in g e d g e o f i n t e r n a l 0 2 a n d s h i f t s a h i g h l e v e l t o IC 5 P 2 . T h i s h i g h l e v e l g e n e r a t e s a n in t e r n a l S Y N C pulse at 1C17P15 . The internat SYNC pu lse enables status strobe d riv ers 1C4 5P 8 and IC4 3P11 (W r ite Output and In terrup t Acknow ledge re sp ectiv e ly ) , d isab les the in com in g bu s dr iv ers on 1 C 3 5 an d t r ig g e r s t h e SY N C p in o f th e T M S S S O I , SY N C i s t e r m in a t e d b y t h e r i s in g e d g e o f 0 2 w h i c h c l o c k s t h e n e x t se c t io n o f IC 5 an d p r e s en t s a h i gh l e v e l a t 1C 5P 1 2 . D u r in g t h i s p e T i o d , th e T M S S S O I in t e r n a l ly a r r a n g e s d a t a p a t h s w h i le th e 4 FD C id le s . W h en 0 2 f a l l s a g a in , IC 2 0 P 6 go e s 1ow w h i c h o p e n s t h e g a t e o f t h e o u t p u t l a t c.h I C 5 0 a dm i t t in g t h e d a t a p r e s e n t a t t h e in p u t s o f I C 3 0 . T h is d a t a h a s c om e fr o m t h e T M S S S O I v i a e x c l u s i v e -o r g a t e s 1 C 5 4 an d 1 C 5 F a n d m u l t i p le x e r 1C 4 9 , T h e e x c l u s i v e -o r s h a v e a c o m m o n in p u t h e l d 1 ow b y a n o u t p u t f r om I C 7 , s o t h e y p a s s t h e d a t a t h r o u gh w i t h o u t in v e r s i o n . M u l t ip l i x e r 1C 4 9 p a s s e s t h e d a t a s t r a i g h t t h r o u g h e x c e p t w h e n t h e 4 F D C i s in t h e p r o c e s s o f r e a d i n g t h e s e r i a l statu s p ort (Inpu t p o rt 00) . c a u s in g th e m u l t i p l e x e r to In th is case a 1C 25135 goes 1ow sw i t ch 1)7 a n d D 6 w i t h 94 an d 5 5 (p rodu cin g the statu s b it assignm en t detailed in Ch ap ter 3) . The cy c l e h i gh lev e l f in a l l y to t e r m in a t e s w h e n 02 r ise s a g a in s h i f t in g a lC 5P 1 6 . Case 5 , Inpu t/ou tpu t Tefe ren ces to p orts 50 - 3414: Wh en IC 7 P 1 2 g o e s 1 o w s i gn i f y i n g d i sk r e f e r e n c e o p e r a t i o n s , t h e c o m m o n p in s o f e x c lu s i v e -o r g a t e s IC s 3 4 , 3 5 , 4 7 , a n d 4 8 g o h i gh . T h i s c au s e s t h e in t e r n a l d a t a b u s o f th e 4F D C t o b e c o m p l e m e n t e d w i t h r e sp e c t t o th e FD 1 7 71 -1 . D u r in g o u t p u t th e S -1 0 0 b u s , a s cy c l e s , d a t a f r o m is latched in to 1C 55 by PWR/ . IC 50 is rea d d u r in g P D B IN . r eq u i re d by th e p r o c e s so r Dur in g inpu t cy cles , la tch 42 C a se 4 , O u tp u t r e fer en c e to p o r t 4 0H ; i s n o t e x a m i n e d b y th e 4 F D C d u r in g b a n k bus on th e W a it S -1 0 0 D 0 State bu s is latch e d in t o 1C 5 5 A lth ou gh th e d a t a se le ct , th e d a t a an y w ay . G en e r a t o r T h e w a it s t a t e g e n e r a t o r , lC 4 2P 1 1 , p a s s e s o n w a i t r e q u e s t s w h en en ab le d b y lC 1 8 . T h e r e a r e f o u r e n a b l in g c o n d i - tion s : 1) 4M H z Inpu ts from p o rts 50-53H , 2) 4M H Z M 1 fetch e s from the R0M at C000 -C 3FFH , 3) D isk referen ce s w ith Au to W ait m ode sele cted , an d 4) Any re feren ce to th e TM S5501 (p orts 00 -09 ) . Th ere are th ree sou rces o f w a it requ est : 1) P SYN C , 2) Re ady from w a it IC 25P 8 , and 3) Ready from TM S5501 (TC 25P 1 2) . T h e c o in c i d e n c e o f a n e n a b l in g c o n d i t i o n s t op s t h e p r o c e s s o r in m i d cy c l e . an d a w a it requ e st C lo ck s The con t r o ls 4 F D C h a s a n 8 ,0 0 0 M H z o n b o a r d c r y s t a l c l o c k w h i c h a 1 1 i n t e r n a l b o a r d t i m in g . IC 2 c o n d it ion s th e c lo ck fo r t h e TM S 5 5 0 1 an d F D 1 7 71 . 2M H z 0 1 a n d 0 2 s i g n a l s g e n e r a t e d a t IC 4 P 5 a n d IC I P I O r e sp e c t iv e ly . A IM H Z are t im i n g s i gn a l IM H Z is g en e r a te d a t I C 2P 1 5 an d a sw i t c h a b l e 2 or clock is gen erated at 1C 2P 16 (con tro lled by th e m ax i/m in i sign al at IC4P 15) . B an k Select Th e IK R0M on b oard th e 4F D C m ay be d is ab le d ou tp u t p or t 40H if sw itch 2 (RE S) is on . th r o u gh In th is case , th e R 0 M i s d e s e l e c t e d p e r m a n e n t ly a f t e r t h e f i r s t o u t p u t t o p o r t 4 0 H c l o c k s f l ip - f l o p 1 C 2 9 P 1 1 a n d f o r c e s 1 C 2 9 P 9 l o w . T h is f o r c e s t h e m e m o r y a d d r e s s d e c o d e r I C 5 0 P 9 h i g h , d e s e l e c t in g th e R OM . T h e RO M m ay b e r e -en ab le d b y a h a r dw a r e RE S E T s i gn a l w h i c h TM S 5 50 1 s e t s 1C 2 9 P 9 h i g h a g a in . In t e r f a c e s lC 1 2 r e q u i r e s inpu ts . 12 v olt c lo ck l ev e l s th e an 02 ser ial ou tp u t IC 1 2P 4 0 is a t t h e in p u t o f o p e n on b r i e fly t o p u l l in v e r t e d an d TT L leve ls to + 12 an d -5 lev e ls by Q 3 an d Q4 . v id e s 0 1 an d Th ese are su pp lied by activ e p u llup s Q1 an d Q 2 w h ic h w h en t r i g g e r e d b y a f a l l in g e d g e c o l l e c t o r in v e r t e r p a c k a g e 1C 2 5 sw i t c h th e in v e r t e r o u tp u t s u p t o 1 2 v o l t s . The at op en co llec to r cu rren t s in k for sh if t e d from 1C 25P 2 p ro - cu r r en t l o op s . 43 M Ae s e r i a l in p u t lC 1 2P 5 is co n t r o l le d by d iscrete NAN D gate m ade up o f Q 5 an 4 Q6 wh ich sh ifts an d inve ' rts -5/+1 2 lev el s to + 5/ 0 v olt lev els . T h e p a r a l l e l in p u t s a n d o u tp u t s a r e b u f f e r e d b y o c t a l b u s b u f fe r s FD 1 771 -1 1C s 1 3 an d 14 . In t e r f a c e s A 1 1 s i g n a l s f r o m t h e d r iv e s a r e T T L b u f f e r e d a n d h a v e 1 5 0 o h m p u l lu p s . M a x i a n d m in i s i gn a l s a r e w i r e d a n d a t t h e p u l l u p s id e o f t h e b u f fe r s . S ign a l s w h ic h d o n o t a p p ly to th e m in i (i .e ., REA DY an d SEP CLO CKI , are d isab led an d p u l le d h i gh w h en w ith ST E P t h e m in i is selected . S i g n a l s t o th e d r i v e s f r o m t h e 1 7 7 1 a r e T T L b u f f e r e d s e p a r a t e b u f f e r s f o r m in i a n d m a x i c o n n e c t o r s Th e o u t p u t i s s t r e t c h e d b y 1 C 5 7 t o ab o u t 1 6 m i c r o s e c o n d s . be fore go in g to the drives . The HLD (head load ) ou tput does n o t g o d i r e c t l y t o th e d r iv e s b u t r a t h e r en a b l e s t h e d r i v e s e l e c t l in e s t h r o u g h I C I O P I . T h u s , t h e a c t u a l d r iv e s e l e c t s i g n a l t o t h e d r iv e i s t h e c o in c i d e n c e o f a l a t c h e d d r iv e selection (done at po rt 34H ) and HLD from the 1 771 . Head l o a d i n g t im e i s d e t e r m i n e d b y c o u n t e r s 1 C 3 6 a n d 2 7 T im e o u t i s c o n t r o l l e d b y t h e c o u n t l o a d e d in t o 1C 5 8 b y 1C 5 5 . . Sign als DRQ , HLD , an d INTRQ (or EOJ ) a re av ailab le at input p ort 54H (IC9) . V arious con trol sign als aTe assign ed to o u tp u t p o r t P r io r i ty Th e 54H an d are l a t ch e d b y IC s 24 an d 41 . C h a in 4FDC in c l u d e s a r ip p l e p r i o r i t y c i r cu i t w h i c h w i l l defeat the interrup t acknow ledge cycle of Priority IN/ is held low . If the 4FDC is allowed to p erform the interrup t ack now ledge , it w i ll p u l l dow n its P rAo r ity O u t/ line to s i g n a l o t h e r s i n t h e c h a in n o t t o r e sp o n d c o m p a t ib l e w i t h t h e C r o m e m c o T U -A R T . . T h i s c h a in is CHA P TE R 8 : PA RT S MFD C R ev i s ion PA RT S IP IC IC IC IC 1 2 3 % S 7%LS 0% 7% 276 7%276 7B L S 0 0 7: 3 67 IC IC 6 7 7% 368 74L51 38 IC 8 L IST 44 B L I ST ' 10 IC 10 IC IC T 7%L S0 0 $9 50 Sl 52 53 7VL Sl S7 7%LS 37 8 7%LS 32 7%L 0% 7VLSl57 r an s i sto r s IC 9 IC 1 0 7% 36 8 74 36 8 Ql 92 2N 390 6 2N 39 0 6 IC FD 93 2N 3 9 0 6 Q% QS Q6 2N 3 9 0 % 2N 39 0 % 2N 3 90 % Dl D 2 D3 LED N T IL-2l l 1N 9 1 % 1N 9 l % 11 1771-1 IC 1 2 IC 1 3 IC 1% TM S 5501 7%L S 2% 1 7% L S 2% 0 I IC 15 7 9 0 5 /LM 3 2 0 - 5 IC IC IC IC IC IC IC IC IC 16 17 18 19 20 21 22 23 2% 7%L S 0% 7%L S 02 74 5 6% 74 25 7ML S1 0 7%LS 0% 7%5260 7: 90 3 7R L S l 7 % D io de s R e s i st o r s IC 2 5 I C 26 7: 0 6 7 % L S 04 R R 1 2 IK k w IK k w IC IC IC IC IC IC 27 28 29 30 31 32 CD % 0 2 0A E 7 %L S 0 8 7%L 5 7 % 7%51 33 2708 74 L 5 9 % R R R R R R 8 % 5 6 7 8 l50 k w 1 0K k w l 0K k w l 0K k w 680 k w IK k w IC 33 7 %5 3 7 3 R 9 3 .3K k w IC 10 IC IC 3% 35 36 37 74 L 5 8 6 7 %L 5 8 6 74 2 0 7 : 1 6% Rl0 R ll Rl2 R13 270 k w %70 k w % .7K k w l 0K k w IC 38 741 61 Rl% l 0K Y I C 39 IC M 0 7 8 1 2 /LM 34 0- 1 2 7 8 0 5 /LM 3% 0- % Rl5 R 16 IC Ml 74L 5 7% Rl7 IC 4 2 IC 4 3 7% 367 7%L S0 3 Rl8 Rl9 IC %% 7%L 0M R20 IC 4 5 7: 36 7 R 2l IC 74 367 R22 7% L 5 8 6 74 L 5 8 6 R23 R 2M 5 .6K k w % .7K k w 5 6K k w 390 k w 1 80 k w % 7K k w 3 30 k w 5 6K k w 330 k w 39 k w 46 IC 4 7 IC : 8 . . . w G r een 45 R e s i st o r s R e si st or ( c o n 't ) C a p a c it o r s ( c o n 't ) R2S 39 k w C% 3 ,l U F c e r a m i e d i s c R 26 R 27 3 30 k w 5 . GK k w C til4 0%S .l U F c e r am i e d i s c .l u F c e r am i e d i s c C L#6 (2117 0%8 .l U F .l u F .l u F N etw ork s RN l S I P N 8p in N 7 R e s i s t o r s RN 2 l 50 ohm S I P , 8p in , 7R e s i s t o r s IK c er am i e d i s c c e r am i e d i s c c e r am i e d i s e M i see ll an e ou s oh m J2 Ca p a c ito r s C on n e ct o r N 5 0P in y C ir c u it A s s em b ly N CA -D b OR S P I O O 2 30- 0 90 C 1 30 p F c er am ic d i sc C 2 10 C C C 3 11 5 .l u F c e r a m i c d i s c .l u F c e r a m i c d i s c .1 U F c e r a m i c d i s c C 6 .l U F e e r am ic C 7 10 t an t a lum 2 IL 110 s c r ew s C 8 1 0 U F t an t a lum 1 H eat S in k C 9 .l u F uF UF J3 t an t alum c er am ic C o n n e c t o r : 3 ttp i n , C i r c u i t A s s e m b l y n C A - D 3 LtR S P I O O - J% d i sc 2 30- 0 9 0 C o n n e c t o r , 2 6 P in , C i r c u i t A s s e m b l y , 0A -D 2 6R S P l 0 0 2 30- 09 0 and Ile x llu t s disc Cl0 .l uF ceram ic disc 1 8 MH z Cry sta l Cl1 C12 C13 .1 u F .l U F .1 u F e er am i c c e r am i c c er am ic di sc d i sc d i sc l F1 S 11 P o l e D m p s w i t c h 6 - 32x 3 / 8 p an h e a d s cr ew s 6 - 3 2 sm a l l p a t t e r n h e x n Cl% C1S .l u F .l u F c er am i c c er am ic disc d isc l 1 P C Boar d S e r i a l I /O Cl6 Cl7 .0 S u F c e r a m i c d i s c .l u F c e r a m i c d i s c cl8 Cl9 C20 .l u y c e r am i c d i s c . l u lr c e r a m i c d i s c .l u F c e r a m i c d i s e C 21 C 22 (22 3 02% 025 C 26 027 (22 8 (22 9 C 30 .0 5 U F c e r a m i e d i s c .l u F c e r a m i c d i s c 75 pF ceram ic d isc 7 F) p F c e r a m i c d i s c .l u F c e r a m i c d i s c .l u F c e r a m i c d i s c .l u F c e r a m i c d i s c .l u F c e r a m i c d i s c .l U F c e r a m i c d i s c .l u F c e r a m i c d i s e C 31 C 32 .0 5 U F c e r am i e d i s c .l u F c e r a m i c d i s c 0 83 C 3 Lp .l .l uF uF cer am ic cer am ic d isc disc C 35 .1 u F c er am i c di sc C 36 C 37 C 38 C 39 C%0 C %l C%2 10 UF 10 UF 10 u F .l U F .1 u 7 . l u lp .l u lp t an t a l um t an t a lum t a n t a lum c er am i e c er am ic c e r am i c ceram ic d i sc disc dise d isc S o ek et s 26 15 6 l 2 y y p s rj 1 6 p in 2 0 p in 2 14 p i n M 0 p in C a b le A s sem b ly 46 CHA PT E R 9 : W A R RAN TY Y o u r f a c t o r y -b u i l t 4 F D C d i s k c o n t r o l l e r c a r d i s w a r r a n t e d a g a in s t d e f e c ts in m a t e r i a l s an d w o rk m an sh ip f o r a p e r i o d o f 9 0 d a y s f r o m t h e d a t e o f d e l iv e r y . W e w ill r e p a i r o r r e p l a c e p r o d u c t s t h a t p r o v e t o b e d e f e c t iv e d u r in g t h e w a r r a n t y p e r i o d p r o v i d e d t h a t t h e y a r e r e tuT n e d t o C rom em co . N o o th e r w ar r an ty i s ex p r e s s e d o r im p l i e d . W e a r e n o t l i ab l e fo r c o n s e q u en t i a l d am a g e s . Y o u r a s s e m b l e d 4 F D C k i t o r y o u r f a c t o r y -b u i l t 4 F D C a f t e r th e w a r r an ty p e r io d w i l l b e r ep a ir e d , p r ov id e d th a t i t i s r e tu rn e d t o C rom e m c o , fo r a s e t s e rv i c e f e e . We r e se rv e th e r i gh t t o r e fu s e to r ep a ir an y k i t th a t w a s n o t a s s e m b l e d in a w o r k m an l ik e m a n n e r o r a n y p r o d u c t that in ou r op in ion h as b een sub ject to abn o rm al e le c t r ic a l o r m e ch an i c a l ab u s e . P ay m en t o f th e s e rv ic e f e e m u s t a c c om p an y th e r e tu rn e d m e r ch an d i s e . The serv ice fee is cu rren tly 1 70 an d is sub ject to c h an g e ,