Components Of The Drive; Generate And Interpret Control And Status Signals; Index Sensor(S); Write Protect Sensor - Tandy 6000 Service Manual

4.2 COMPONENTS OF THE
DRIVE
T h e d r iv e c o n ta in s th e e le c tr ic a l a n d m e c h a n i­
c a l c o m p o n e n ts r e q u ir e d
m a jo r fu n c tio n s :
1. G e n e ra te a n d
s ta tu s s ig n a ls .
2. P o s itio n th e r e a d /w r ite h e a d (s ) to th e
d e s ire d tr a c k .
3. W r it e a n d re a d d a ta ,
4. C o n tro l th e s p in d le .
T h e e le c tr ic a l a n d m e c h a n c ia l c o m p o n e n ts o f
th e d r iv e a re c o n n e c te d to g e th e r v ia m u lt i- p in
c o n n e c to rs ( F ig u r e 4 -4 ). T h is a llo w s th e i n d i ­
v id u a l a s s e m b lie s to be re m o ve d .
A l l m a jo r fu n c tio n s , o th e r th a n th e re a d d a ta
c ir c u its , a n d p a r t o f th e w r it e d a ta c ir c u its ,
a re m o n ito r e d b y th e L S I c h ip a n d th e m ic r o ­
pro cesso r. T h e m ic ro p ro c e s s o r g e n e ra te s th e
re q u ir e d o u tp u t s ta tu s s ig n a ls a n d c o n tro ls
th e fu n c tio n s o f th e d riv e .
4.3 GENERATE AND
INTERPRET CONTROL
AND STATUS SIGNALS
T h e c o m p o n e n ts o f th e d r iv e r e q u ir e d to g e n e r­
a te a n d in t e r p r e t th e c o n tro l s ig n a ls a re :
1. In d e x S ensor (s)
2. W r it e P r o te c t Sensor
3. T r a c k 0 S w itc h
4. L e v e r C losed S w itc h
5. L e v e r L o c k S o le n o id

INDEX SENSOR(S)

T h e in d e x s ig n a l is d e riv e d fr o m a n in fr a r e d
L .E .D . a n d p h o to tr a n s is to r d e te c to r. W h e n th e
in d e x /s e c to r h o le in
th r o u g h th e in d e x sensor, th e l i g h t fr o m th e
to p e r fo r m f o u r
in t e r p r e t c o n tr o l a n d
th e d is k e tte passes
L .E .D . is a llo w e d to t u r n on th e in d e x d e te c to r,
p ro d u c in g a p o s itiv e p u ls e on T e s t P o in t 1, fo r
in d e x n u m b e r tw o sensor, a n d T e s t P o in t 2 fo r
in d e x n u m b e r one sensor.
T h is s ig n a l is s u p p lie d to th e m ic ro p ro c e s s o r
f o r tim in g . I t is a lso g a te d in t e r n a lly in th e
L S I c h ip w it h
c o n tr o l s ig n a l a t th e in te r fa c e (F ig u re 4-5).

WRITE PROTECT SENSOR

W h e n a w r it e p ro te c te d d is k e tte is in s ta lle d ,
l i g h t fr o m th e w r it e p r o te c t L .E .D . is d e te c te d
b y th e w r it e p r o te c t se n so r tr a n s is to r, c a u s in g
th e o u tp u t o f th e sensor to be h ig h a t T e s t
P o in t 5. T h e s ig n a l, g a te d in t e r n a lly in th e
L S I c h ip w it h D R S E L + , g e n e ra te s th e W r ite
P r o te c t s ig n a l. I f a w r it e p ro te c te d d is k e tte is
in s e rte d , w r it e g a te is d is a b le d .

TRACK 0 SENSOR

T h e T r a c k 0 sensor s ig n a l is d e riv e d fr o m a n
o p tic a l sen sor in t e r n a l to th e d riv e . A s th e
h e a d c a rria g e m o ve s b a c k to w a r d T r a c k 0, th e
se n so r is d e a c tiv a te d b e tw e e n T ra c k s 1 a n d 2
(F ig u re 4 -6 ).
T h is s ig n a l p ro d u c e s a lo w o u tp u t on T e s t
P o in t 3, w h ic h is s u p p lie d to th e L S I c h ip . T h e
c o m b in a tio n o f th e T r a c k 0 sensor b e in g d ea c­
tiv a te d a n d th e
(P hase Z ero) p ro d u c e s th e p ro p e r T r a c k 0
s ig n a l, g a te d in t e r n a lly w it h D r iv e S elect, to
th e in te r fa c e c o n n e c to r, P I P in 42.
LEVER CLOSED SWITCH
T h e L e v e r C losed S w itc h s ig n a l is d e riv e d
fr o m a m e c h a n ic a l s w itc h m o u n te d in t e r n a lly
in th e d r iv e . W h e n th e le v e r is closed, a h ig h
(tru e ) s ig n a l is p ro d u c e d on P3, P in 12, a n d
s u p p lie d to th e L S I c h ip .

DRIVE SELECT

T h e d r iv e s e le c t s ig n a l is s e n t fr o m th e h o s t
c o n tr o lle r to th e in te r fa c e c o n n e c to r.
4-3
d r iv e s e le c t f o r a n o u tp u t
p ro p e r s te p m o to r phase