Tektronix 070-8030-01 318 1780R-Series Service Manual, Table 32: Input Channel Selection Logic

Theory of Operation
3–18 1780R-Series Service Manual
Table 3–2: Input Channel Selection Logic
per i M e
p
(U1415) (U1415) Par
Mode Internal Reference
O
per
at
i
ng
M
od
e
In
p
ut(s) I1I2I3I4I5I6I7I8
SINGLE INPUT A 00000000CH A
SINGLE INPUT B1 00010000CH B1
SINGLE INPUT B2 00100000CH B2
SINGLE INPUT B3 00110000CH B3
SINGLE INPUT PROBE 0 1 1 1 0 0 0 0 PROBE
DIFFERENTIAL A B1 00001000CH A
DIFFERENTIAL B1 B2 00011010CH B1
DIFFERENTIAL B1 B3 00011100CH B1
PARADE A + B1 10000001CH A
PARADE A + PROBE 10010001CH A
PARADE B1 + PROBE 10100001CH B1
PARADE B1 + B2 + B3 11110001CH B1
PARADE B1 B2 + B2 B3 00011111CH B1
OVERLAY A + B1 10000000CH A
OVERLAY A + PROBE 10010000CH A
OVERLAY B1 + PROBE 10100000CH B1
OVERLAY B1 + B2 + B3 11110000CH B1
OVERLAY B1 + B2 11000000CH B1
OVERLAY B1 + B3 11010000CH B1
OVERLAY B2 + B3 11100000CH B1
WFM + CAL A + CAL 00000010CH A
WFM + CAL B1 + CAL 00010010CH B1
WFM + CAL B2 + CAL 00100010CH B2
WFM + CAL B3 + CAL 00110010CH B3
WFM + CAL PROBE + CAL 0 1 1 1 0 0 1 0 PROBE
CALIBRATOR CAL SIG 0 1 0 1 0 0 1 0 GROUND
CALIBRATOR OSC CAL OSC 0 1 0 1 0 1 0 0 GROUND
Decoders U1316 and U1523 convert the 3-bit logic array outputs to single active
high signals. When an input mode requires dynamic switching of inputs, such as
A/B Parade or B1-B2/B1-B3, the U1415 state machines cycle their outputs
through the appropriate sequence, timed by sync and the horizontal retrace pulse.