Operation - IBM System/32 Introduction And Maintenance Manual

5.3.0 OPERATION
All functions except the high voltage oscillator
and brightness control are directly synchronized
by the attachment.
The display attachment controls the CRT circuits
as described below.
To move the electron beam vertically and hori-
zontally across the CRT to form a continuous
raster:
1.
The attachment activates three vertical
input lines in a continuous binary se-
quence to select one of the six display
lines
I! .
2. The attachment activates horizontal de-
flection circuits that move the beam left
to right across the screen
iii '
then
retraces
II
right to left to begin the
next line
m .
3. The attachment activates character con-
trol (wiggle sweep) pulses
II .
Ten wig-
gle sweep pulses are one character time.
The vertical distance equals the height of
the character plus the cursor. Wiggle
sweep is blanked out during most of the
retrace time
II.
To intensify the raster with dots to form a char-
_acter, the attachment activates the video line
with a combination of pulses to control the
video amplifier. These pulses, comQined with
the electron beam wiggle sweeps across the CRT,
form the character
'II .
The preceding description assumes that you are
looking at the display
iii .
After taking
the mirror off the machine, or the display unit
out of the machine, the display appears upside
down (line 1 at the bottom of the CRT) as shown
m·
Vertical Input
Display
Line 1 2 4
1
0 0 0
2
1
0
0
3 0 1
0
4 1 1
0
5
0 0
1
6
1 0 1
1
0 0 0
2
1 0 0
3
0 1 0
.Vertical
l :
Input
4
Horizontal
Input
•
I • •
24 ms (6 lines)
approximate
~
..
5-4
L
I
I
I
I_
1 Character Position
_I
m
lo ____________ DATA LINE __________ 40
4lo ___________ DATA LINE _________ -80
8lo __________ DATA LINE _________ lo20
lo2lo _________ DATA LINE _________ :L60
:L6lo _________ DA TA LI NE _________ 200
20:L _________ DATA LINE _________ 240
m
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