Tektronix 7834

<-
STORE COMMAND
TO
ALL
MEMORIES
TIME-SLOT 5
4
INTERROGATION PULSES
TIME-SLOT
6
3
--am

ENABLE TO ALL MEMORIES
RESET TO ALL MEMORIES
If data was encoded during time-slot 1, a negative-going
output is produced at pin 7 while the memories are being
set . - This negative-going pulse is connected to the base of
03414 in the Display-Skip Generator to produce a Display-
Skip output . Since the information encoded during time-
slot 1 was only provided to set the memories and not
intended to be displayed on the crt at this time, the Display-
Skip output prevents a readout display during this time-slot
.
During time-slot 5, memory A
is interrogated . If information
was stored in this memory, a
positive-going output is pro-
duced at pin 7 . This pulse is connected
to pin 10 of the
Column Decoder through 03419 to add one unit
of
current
at the input of the Column Decoder . This produces a zero
TIME-SLOT 8
6
MEMORY
D
(IDENTIFY)
Figure 3-36 . Block representation of memory
sequence in U3401 .
Theory of Operation--7834
1195-35
after the character displayed during time-slot 4 . During
time-slot
6,
memory B
is interrogated to see if another zero
should be
added .
If
another zero is necessary, a second
positive output is
produced at
pin
7, which again results in
a column 1 output from the Column Decoder and a second
0 in the crt display .
Finally, memory C is interrogated during time-slot 8 to
obtain information on whether the prefix should be chang-
ed, or left at the value that was encoded . If data has been
encoded that calls for a shift in prefix, a negative-going
output level is produced at pin 7 . - This negative level sub-
tracts one unit
of
column
current
from
the data at the input
to the Column
Decoder
.
Notice on the Character Selection
3- 4 7
COLUMN 1 12
COLUMN 2
13
COLUMN 3 10
COLUMN 4 11
COLUMN 10
14
TIMESLOT 1
ROW 3 16
WORD
TRIGGER