Troubleshooting Tools
Product Manual 37
3.4.5 Disk drive
The signal interface with the disk drive; TTL levels “0” <=> 0V, “1” <=> +5V.
X9
Pin A Explanation
9 RD N Read Data, pulses. Data pulses when reading the dis-
kette
10 WP N Write Protect, static active low. Indicates whether or
not the diskette is write protected.
11 DSKCHG N Disk Change, static active low. Indicates whether or
not there is a diskette in the unit.
12 WD N Write Data, pulses. Data pulses when writing to the
diskette.
13 SSO N Side Select, static active low. Indicates which side of
the diskette is active.
14 DIRC N Direction in, static active low. Indicates that the
heads are to move inwards.
15 0V
X9
Pin C Explanation
9 IP N Index, pulses. One pulse per cycle, c. every 200 mil-
liseconds.
10 TR00 N Track 00, active low. Indicates that the heads are
located at track 0 of the diskette.
11 MO N Motor on, static low. Starts the motor in the selected
unit.
12 WG N Write Gate, pulses. Enables writing.
13 STEP N Step, pulses. Steps the heads in the direction indi-
cated by DIRC N.
14 HD N High Density, static active low. Indicates that a 1.44
MB diskette is in the unit.
15 0V
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