Control Data Corporation INFORMATION SYSTEMS TERMINAL II Hardware Maintenance Manual page 115

The keyboard interface, as presented at the internal con-
troller board connector AJ2, consists of the signals listed
in table 4-11.
TABLE 4-11. KEYBOARD CONNECTOR AJ2 (INTERNAL)
PIN NO. SIGNAL
AJ2-1
Ground
AJ2-2 -Strobe
AJ2-3
+KBD 00
AJ2-4 I 01
AJ2-5
02
AJ2-6 03
AJ2-7 04
AJ2-8
+KBD 06
AJ2-9 -Shift
AJ2-10
+5 V dc
The signals +KBD XX are the outputs of a counter residing
on the controller board. The keyboard decodes these 6
signed lines to select one of the 64 keys. The keyboard
passes the state of the selected key back to the controller
via the Strobe signal: logical high when at rest; logical
low when depressed. If a particular selection (count)
results in an active Strobe reply (logical low), then the
controller logic
1. Delays (debounces) the signal
2. Stops the counter
3. Sets the Keyboard Data Ready status/interrupt
4. Passes the current counter outputs to the processor
(program) upon request
5. Enables the counter to continue scanning after being
statused by the processor.
82100083
NOTE
The design/layout of the keyboard is
such that the output of the counter
to select a particular key is equal
to the code assigned to that key.
This means that the keyboard does not
send the keycode to the controller,
only the state of the selected key.
4-53