Table of Contents
Advertisement
selects the Read/Write head on side zero, the
lower head of the dr i ve. A t r u e ( l ow) level on
this line selects the Read/Wr it e head on side
one, the upper head of the drive. When switch-
ing from one head to th e ot h er, a 100 mi cr o-
second delay is required before any Read or
Write operation can be initiat ed.
H EAD LOAD LINE/MOTOR CONTR O L
This line ma y b e u sed to control t h e spindle
m otor a n d /o r
t h e l e v e r l o c k s o l e n oi d ( s ee
Section 3.6).
OUTPUT CONTROL LINES
There are eight output l i n es, five of which are
standard and three of which are strappable
f eatures. Th e s t a n d ar d o u t pu t s i g n al s a r e :
Index/Sector, Tr ac k
D ata, and Ready. The str appable output s i g -
n als are D i s k C h a n ge, Tw o-Sided, and T r u e
Ready.
INDEX
T he Index signal represents the output of t h e
Index sensor. An Index pulse is provided once
every revolution, 166.67 milliseconds nominal,
t o indicate t h e b e g i n n in g o f a t r a c k t o t h e
c ontroller. Th e l e a d in g e d g e o f t h i s s i g n a l
m ust
a l w a y s be u s e d t o en s u r e t im i n g
a ccuracy. The Index l in e r em ains in t h e t r u e
(low) state for the duration of the Index pulse,
which is nominally four mi l l i seconds.
TRACK 0
W hen the drive is selected, the Track 0 i n t er -
f ace signal indicates to the controller that t h e
Read/Write head is positioned on Track 0, the
o utermost t r a ck . T h i s s i g n a l r e m a i n s t r u e
( low) u n t i l
t h e R e a d / W r i t e h e a d i s m o v e d
away from Track 0. This signal is false (high)
when the selected drive's Read/Writ e head is
not on Track 0.
0 , W r i t e P r o t e ct , R e ad
WRITE P ROTECT
T he Writ e P r otect si gnal i s pr ovided to i n d i -
cate to the user that a write protected diskette
is installed. This signal is true (low) when the
diskette's W r i t e P r o t ect n o tch i s u n c overed.
When the Writ e Pr otect signal is false (high),
t he wr it e e l ectronics are enabled, and w r i t e
operations can be performed.
READ DATA
The Read Data line tr ansmits data to the con-
troller when the drive is selected and not
w riting. It pr ovides a pulse for each flux tr a n -
sition recorded and detected on the diskette by
t he drive electronics. Normally, this signal i s
f alse (hi gh) . I t
active state. The Read Data output line goes
true (low) for a duration of 200 nanoseconds,
~ 50 nanoseconds, for each ch ange r ecorded
on the diskette.
READY
The Ready i n t e r f ace signal i n d i cates a di sk -
ette has been inserted into the drive. Ready
w ill no t
r e t u r n t o t h e f a l s e s t at e u n t i l t h e
lever is opened, and is not affected by Spindle
Motor Control.
W hen a
s i n g l e -sided d i s k e tt e i s in s t a l l e d ,
Ready is activ e (l ow) i f
Ready is false (high) if side one is selected on
t he TM848-1E. When a t w o -sided diskette i s
installed, Ready is active when either side of
the diskette is selected on the TM848-2E.
TRUE READY
The True Ready interface signal indicates the
diskette is r o t a t in g a t 3 6 0 RP M a n d a s e ek
operation is complete, i.e., the head has
settled. This may be used to indicate seek com-
plete when using the buffered seek operation.
3-5
b e c omes t r u e ( l ow ) f o r t h e
s i d e zero is selected.
Advertisement
Table of Contents
