I can't seem to get the 4-bit shift reg to work. I wire an 8-bit and a 4-bit shift reg up the same way, and only the 8-bit version does anything.

I'm not using the SLI/SRI pins because there's no documentation so I don't know what they're supposed to do.

Set P1 high on both
Set S1 and S2 high on both.
Expected result: Both chips will output to P1
Actual result: 4-bit chip outputs nothing. 8-bit chip properly outputs to P1

replace P1 with any other pin for my remaining tests.