Control Data Corporation INFORMATION SYSTEMS TERMINAL II Hardware Maintenance Manual page 105

Input Parallel Channel
(InpUg~~!l
- Any input instruc-
tion whose address has bit 2 set indicates a transfer of
data from external devices to the processor.
OU!2ut Parallel Channel (Ou!2ut 2!L 3X) - Any output
Instruction whose address has bit 2s-set indicates a
transfer of data from the processor to an external device.
Composite Video Interface
The composite video interface generates and supplies a non-
interlaced, composite video signal equivalent to and in
synchronous with the picture being displayed on the termi-
nal screen. The output signals consist of three voltage
levels:
V out
=
0.0 to 0.2 V sync level
V out
=
0.5 to 0.7 V black level
V out
=
1.5 to 1.7 V white level
The video information is digital, black or white, with no
intermediate gray levels.
The maximum data rate supplied by this interface is 12.048
mHz (41.5 nanoseconds, white: 41.5 nanoseconds, black).
The timing of the signals is nonstandard. Figures 4-20 and
4-21 show the 60-Hz and 50-Hz timing for the line and frame
portion of the signals.
A display monitor connected to this interface duplicates
the image of the terminal display when:
• Line scanning (34.23 kHz rate) is performed horizon-
tally, from left to right of the screen (retrace
from right to left)
• Frame scanning (SO or 60 Hz) is performed verti-
cally, fram top to bottom (retrace from bottom to
top) •
82100083
4-43