Input Lines; Basic Oscillator; Error; Busy Tone - IBM System/32 Introduction And Maintenance Manual

6.1.2 Input Lines
Basic Oscillator
This line contains oscillator pulses. The oscil-
lator pulses are on this line as long as power is
on the system.
-1
r-
4tl
s
~
Basic Oscillator
Repeat Oscillator
This line contains oscillator pulses. The oscil-
lator pulses are on this line as long as power is
on the system.
-1
131 ms
r-
~
Repeat Oscillator
Error
The error line active prevents clicker operation,
but does not prevent data from appearing on
the bit lines. This line is activated by the at-
tachment whenever an operator error occurs or
a keyboard overrun occurs (see Clicker, 6.1.1).
Busy Tone
Some keys always operate the clicker regard-
less of the status of the error I ine or the
KEYBD ROY light. The attachment accom-
plishes this by activating the busy tone line
for 8.19 ms. The busy tone line overrides the
error line and allows a click. The keys that
always operate the clicker are PAGE/LINE,
PRINT/RESET, and ERROR RESET. In addi-
tion to the preceding keys, the I NQ key also
operates the clicker regardless of the status of
the error line. However, this click is generated
in the keyboard and does not depend on the
busy tone line from the attachment.
6.1.3 Output Lines
Kbd Go
This line signals the attachment that a character
is available on the bit lines. This line is generated
by all keys except the SH I FT key and the REP
key. Its relationship to the bit lines is shown in
the following illustration:
I-
12
tls..J
+
Kbd Go _ _
r - L -
--j
l-
411'
I
- Bit lines
L
I
1---
20 tls
--..J
This pattern is repeated every 131 ms by pressing
a
REP key concurrently with a character or func-
tion key.
Input lines
- Error
+
Kbd Go
6-2
Bit lines
Data is placed on the bit lines within 16.15 ms
after a key is pressed. The relationship between
these lines and the kbd go line is shown in the
preceding illustration.
Data placed on the bit lines leaving the key-
board is not in a standard code but
i~
in a code
unique to this keyboard. Translation of this
data to EBCDIC is done by the microprogram.
The keys and the bits they generate, are shown
in the illustration (6.1.4).
Keyboard
PC Board
Probe Points
• •
2
•
•
3
•
•
4
•
•
5
Basic Osc
- Bits (Shift, 1, 2, 3,4, 5, 6, 7)
• •
6
• •
7
Repeat Osc
- Busy Tone
- Power on Reset
• •
8
• •
9
• •
10
• •
11
CE Ground
;l.ziJ!f
Test Pin
~
Audio Feedback Drive
and +8.5V Audio Supply
1
Clicker