Texas Instruments 990 Manual page 98

J11s\ _ _ _ _ _ _ _
~
945424-9701
Tabie i-iO. Modei 9ii VDT Character Decoder ROM Table
ROM INPUTS ROM OUTPUTS
x
0 0 0 0 0 0 0 0 0 0 0 0 0
+
128
x
0 0 0 0 0 0 0 0 0 63
+
227
x
0
0 0
I
0 0 0 0 0 0
I
90
+
218
I
x
0 0
0
0
BALL
DRIVE
0 0 0 0 0 82
+
210
x
0 0 0 0 0
0
0
79
+
207
I
x
0 0 0 0
I I
0 0 0
0
0 1
I
74
+
202
*
ROM IS PROGRAMMED TO BE INDEPENDENT OF Ul'USED H INPUT.
(A)1 36304
Composite Sync (CSQ) indicates that either HSQ or VSQ is high. Composite Sync is not,
however, the logical OR of HSQ and VSQ. During vertical sync, Vertical Sync is serrated with
pulses simiiar
to
Horizontal Sync to maintain horizontai synchronization during vertical synchro-
nization. The positive transition of Composite Sync is always enabled at character time 82.
During vertical sync the negative transition occurs at the next character 74 time. Normally (not
during vertical sync), the negative transition occurs at character time 90.
1-88
Digitai Systems Division