Tektronix Webcam 070-8030-01 User Manual
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
Mode
Internal
Reference
Reference
Operating Mode
Input(s)
I
1
I
2
I
3
I
4
I
5
I
6
I
7
I
8
SINGLE INPUT
A
0
0
0
0
0
0
0
0
CH A
SINGLE INPUT
B1
0
0
0
1
0
0
0
0
CH B1
SINGLE INPUT
B2
0
0
1
0
0
0
0
0
CH B2
SINGLE INPUT
B3
0
0
1
1
0
0
0
0
CH B3
SINGLE INPUT
PROBE
0
1
1
1
0
0
0
0
PROBE
DIFFERENTIAL
A B1
0
0
0
0
1
0
0
0
CH A
DIFFERENTIAL
B1 B2
0
0
0
1
1
0
1
0
CH B1
DIFFERENTIAL
B1 B3
0
0
0
1
1
1
0
0
CH B1
PARADE
A + B1
1
0
0
0
0
0
0
1
CH A
PARADE
A + PROBE
1
0
0
1
0
0
0
1
CH A
PARADE
B1 + PROBE
1
0
1
0
0
0
0
1
CH B1
PARADE
B1 + B2 + B3
1
1
1
1
0
0
0
1
CH B1
PARADE
B1 B2 + B2 B3
0
0
0
1
1
1
1
1
CH B1
OVERLAY
A + B1
1
0
0
0
0
0
0
0
CH A
OVERLAY
A + PROBE
1
0
0
1
0
0
0
0
CH A
OVERLAY
B1 + PROBE
1
0
1
0
0
0
0
0
CH B1
OVERLAY
B1 + B2 + B3
1
1
1
1
0
0
0
0
CH B1
OVERLAY
B1 + B2
1
1
0
0
0
0
0
0
CH B1
OVERLAY
B1 + B3
1
1
0
1
0
0
0
0
CH B1
OVERLAY
B2 + B3
1
1
1
0
0
0
0
0
CH B1
WFM + CAL
A + CAL
0
0
0
0
0
0
1
0
CH A
WFM + CAL
B1 + CAL
0
0
0
1
0
0
1
0
CH B1
WFM + CAL
B2 + CAL
0
0
1
0
0
0
1
0
CH B2
WFM + CAL
B3 + CAL
0
0
1
1
0
0
1
0
CH 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.
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.