Programming instructions

The signals to and from the KSR to the control logic are standard serial,
7.5-unit-code Teletype signals. The signals are: start (1.0 unit), information,
bits 1-5 (1.0 unit each), and stop (1.5 units). Figure 17 illustrates the
current pattern produced by the binary code 10110.
0 (Current)
100 MS
1 Unit = 33.33MS 1 1
1 1
i
i
1.5
Start Bit 1
Signal
Sit 5
stop (Return to
Signd
Idle Line)
Figure 17 - Teletype timing of information code 10110
KEYBOARD
The Keyboard control contains a 5-bit buffer (KB) which holds the code for
the last key struck. The Keyboard flag signifies that a character has been
typed and its code is present in the Keyboard buffer. The Keyboard flag
and Keyboard buffer are cleared each time a character starts to appear
on the Teletype line. The Keyboard flag becomes a 1, signifying the buffer
is full 0.5 f 0.125 units after the end of information bit 5, or 86.6 milli-
seconds after key strike time. The instructions to manipulate the Keyboard
are:
ksf - 700301 - Skip if the Keyboard flag is a 1, i.e., character present.
krb - 700312 - Read Keyboard buffer. Clear the Keyboard flag. C(KB)=>
WC)
700302 - Clear the Keyboard flag. C(KB)V C(AC)=> C(AC)
0 10 20 30 40 50 60 70
80 90 100
MS
Key
86.8
Strike
I I
KRB
Char.
Avail.
In KB
Char.
Assem.
In Kt3
Computing Time=lOOMS
Between Characters
At Maximum Rate
Figure 18 - Keyboard timing
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