Radio Shack TRS-80 III User Manual

termination of the WR ITE ENAB LE signal. When the
WR ITE ENABLE line is false (high), all write electronics
are disabled.
When a write protected diskette
is installed in a Disk Drive,
the write electronics are disabled irrespective of the state
of
the WR ITE ENABLE line.
SIDE SELECT (SDSEL)
When this signal
is true (low), one side of a double-headed
drive
is selected. When this signal is false (high), the other
side of the drive is selected.
OUTPUT STATUS
(See Table
1)
INDEX PULSE (lp*)
The INDEX PULSE signal is provided once each revolution
(200 mSec, nominal) to indicate to the controller the begin-
ning
of a track. The INDEX PULSE line remains in the true
(low) state for the duration of the INDEX PULSE (The
duration
of an INDEX PULSE is nominally 4.0 mSec).
The leading edge
of an INDEX PULSE must always be used
to ensure diskette interchangeability between Disk Drives.
TRACK
00 (TRK0*)
When the Disk Drive is selected, the TRACK 00 interface
signal indicates
to the controller that the read/write head is
positioned at Track 00. The Track 00 remains true (low)
until the head is moved away from Track 00.
WRITE PROTECT (WPRT*)
When the Disk Drive
is selected, this signal line logic level
goes true (low) when the diskette is write protected. The
write electronics are internally disabled when
the diskette
is write protected.
NOTE: It
is recommended that the write data line be in-
active whenever Write Enable is false (i.e., read state).
When the
level on this line is false (high), the write electron-
ics
are enabled and the write operation can be performed. It
is recommended that the controller not issue a write com-
mand when the
WR ITE PROTECT signal is true (low).
READ DATA (RD*)
This interface line transmits the read back data
to the con-
troller when the D
rive is selected. It provides a pulse for
each flux transition recorded on the medium. The READ
DATA
output line goes true (low) for a duration of 1 pSec
for each flux change recorded.
The leading edge of the READ DATA
output pulse repre-
sents the true positions for the flux transitions on the disk-
ette surface.
103

Radio Shack TRS-80 III Specifications

General

Brand	Radio Shack
Model	TRS-80 III
Category	Desktop
Language	English