Tandy 2000 Service Manual page 100

Tandy@
Model
2000
Service
ltlanual
When
a
SEEK command
has been issued by the
FDC,
the
RVSEEK
output is set high (logic 1). This
enables two
drivers
and
two
receivers
on
the 74L524I.
The
drivers control the
FDD
head
direction
(DIR) and step pulses
(STp) which
are
output
to the disk drive(s).
The
receivers monitor track 0 status
(TRK00)
and
the
two-sided
media
input (TS)
to the
8272 which
is
used
as a
motor bn
status port.
7.L.9.9
FDC
Reset Control
The
reset input to the
8272
is
under software
control for
programming
flexibility.
A
reset is output to the
FDC
(FDCRST*)
by the
74L5273
(sheet 13
of
trlain
Logic
schematic)
when
a
WRITE
instruction to
address
0000H
is
executed
to
set
to a low state (logic 0) bit 5 of the data byte written.
-
91