[evlatests] Three bit samplers

[Barry Clark]

I admit it has taken me a few too many years to realize it, but we
have the three bit samplers wired wrong.

T304s have outputs labeled 0 for 8bit sampler, 1,2 for three bit samplers.

Connection from D30x to T304-x is (cf block diagrm on wall downstairs)

D301 to T304-a(0) and (T304-a(1) and T304-c(1))
D302 to T304-c(0) and (T304-b(1) and T304-d(1))
D303 to T304-b(0) and (T304-a(2) and T304-c(2))
D304 to T304-d(0) and (T304-b(2) and T304-d(2))

Better connection is

D301 to T304-a(0) and (T304-a(1) and T304-c(1))
D302 to T304-c(0) and (T304-a(2) and T304-c(2))
D303 to T304-b(0) and (T304-b(1) and T304-d(1))
D304 to T304-d(0) and (T304-b(2) and T304-d(2))

This would permit operating IFs AC in eight bit mode and IFs BD
in three bit mode (or vice versa), which does not work with the
current wiring.