Tektronix 7834

Theory of Operation--7834
The Column analog data is defined by the resistors
shown
between R 110 and R 190 . The program resistors are con-
nected to the time-slot lines by switch closures to encode
the desired data . The data as encoded by the circuit shown
in Figure 3-34 indicates a 100 microvolt sensitivity
with the
crt display inverted and calibrated deflection factors .
This
results in the idealized output current waveforms
shown in
Figure 3-35 at the column analog data output, terminal
A37
of the plug-in interface .
Resistor R111, connected between time-slot 1 and the
column analog data output, encodes two units of current
during time-slot 1 . Referring to the Character Selection
Matrix (Fig . 3-27), two units of column current,
along with
the two units of row current encoded by resistor R 10
(row
3), indicates that two zeros should be added to the
display
.
TIME-SLOT
PULSES
FROM
READOUT
SYSTEM
3- 44
* NOT USED IN STANDARD FORMAT .
Resistor R 120 adds one unit of column current during
time-
slot 2, and along with the one unit of current from the row
output the Readout System is instructed to add an invert
arrow to the display . Resistor R 130 is not connected to
the
time-slot 3 line, since the deflection factor is calibrated
.
Therefore, there is no display on the crt . (See
Display-Skip
Generator for further information .)
During time slot 4, two units of column current
are encoded
by R140 . There is no row current encoded during this
time-
slot ; this results in the numeral 1 being displayed on
the crt .
Neither row nor column analog data is encoded during
time-
slots 5, 6, and 7 as defined by the Standard Readout
For-
mat, shown in Table 3-4
.
During time-slot 8, two
units of
column current and three units of row
current are encoded
by resistors R 181 and R80, respectively . This
addresses the
p prefix in the Character
Selection Matrix, Figure 3-27 .
O
_ I

COLUMN
ANALOG
DATA TO
I

READOUT
SYSTEM
V
B37
01n .
75 K
I
----_--e--

)
A37
Figure 3-34 . Typical encoding scheme for voltage-sensing plug-in unit . Coding shown for deflection factor of 100 microvolts .
ROW
ANALOG
DATA TO
READOUT
SYSTEM
1195-33