IBM 5150 PC Technical Reference (6025005, August, 1981) (PDF)

I/O Channel Description
A9-AO:
D7-DO:
1""""'\ lOR, lOW:
AEN:
+SV:
GND:
AI9-AlO:
MEMR,MEMW:
DACKO-DACK3:
IRQ7-IRQ2
DRQ3-DRQ1:
ALE, TIC:
I""""'\CLK, OSC:
Address lines 9 through 0 are used to
address the Game Control Adapter.
Data lines 7 through 0 are the data bus.
I/O Read and I/O Write are used when reading
from or writing to an adapter (IN, OUT).
When active, the adapter must be inactive
and the data bus driver inactive.
Power for the Game Control Adapter.
Common ground.
Unused
Unused
Unused
Unused
Unused
Unused
Unused
1/0 CHCK: Unused
I/O CH RDY:
HRQI/O CH:
RESETDRV:
-Sv, + 12v, -12v:
Interface Description
Unused
Unused
Unused
Unused
The Game Control Adapter has 8 input lines, 4 of which are digital
inputs and 4 of which are resistive inputs. The inputs are read with one
IN from address x'20 1'.
The 4 digital inputs each have a lK ohm pullup resistor to +SV. With
~ no drive on these inputs, a' l' is read. For a '0' reading, the inputs must
be pulled to ground.
The 4 resistive inputs, measured to +SV, will be converted to a digital
pulse with a duration proportional to the resistive load, acccording to
the following equation:
Time = 24.2 fJ-sec + 0.011 (r) fJ-sec
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