I do the same for testing dip switches, like on Atari pinball MPUs, turn all of them on, read FF, turn all off, read 00.

Yep, I usually reset my dips to Factory when working on a board so I add that step too.

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
! DIP SWITCH TEST
!
! The DIP Test is 3 stages, a All on test, All off test, Factory settings
!
! Set REGF = *DIP1 location
! REGE is contents of previous 9010A command, so use it.
!
! I could not get it to compare to REGE so I used REG1 = REGE and then
! compared to REG1.
!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

PROGRAM DIPTST

REGF = 4008

SW1ON:
   DPY- TURN ALL DIPS ON AT R8 #
   STOP
   READ @ REGF
   REG1 = REGE
   IF REG1 = FF GOTO SW1OFF
   DPY- ERROR R8 OFF PRESS CONT #
   STOP
   GOTO SW1ON
SW1OFF:
   DPY- TURN ALL DIPS OFF AT R8 #
   STOP
   READ @REGF
   REG1 = REGE
   IF REG1 = 0 GOTO SW1FACTORY
   DPY- ERROR R8 ON PRESS CONT #
   STOP
   GOTO SW1OFF
SW1FACTORY:
   DPY- FACT SET SW1 00000001 #
   STOP
   READ @REGF
   REG1 = REGE
   IF REG1 = 80 GOTO SW2
   DPY- ERROR R8 FACT PRESS CONT #
   STOP
   GOTO SW1FACTORY

SW2:

REGF = 4A00

SW2ON:
   DPY- TURN ALL DIPS ON AT R10 #
   STOP
   READ @ REGF
   REG1 = REGE
   IF REG1 = FF GOTO SW2OFF
   DPY- ERROR R10 OFF PRESS CONT #
   STOP
   GOTO SW2ON
SW2OFF:
   DPY- TURN ALL DIPS OFF AT R10 #
   STOP
   READ @REGF
   REG1 = REGE
   IF REG1 = 0 GOTO SW2FACTORY
   DPY- ERROR SW1 ON PRESS CONT #
   STOP
   GOTO SW2OFF
SW2FACTORY:
   DPY- FACT SET R10 00000001 #
   STOP
   READ @REGF
   REG1 = REGE
   IF REG1 = 80 GOTO SW3
   DPY- ERROR SW1 FACT PRESS CONT #
   STOP
   GOTO SW2FACTORY

SW3:

DPY-DIP TEST COMPLETE. PRESS
DPY-+ CONT%1#
STOP

Warning - Random blather below:
I am looking at automating the reading of switch matrixes by a simple jumper plug with some diodes. Have the Strobes all going to a separate Return, or , better yet, matrix all the possibilities with a wiring blob (diodes and wire), and then treat the switch matrix as if it was a RAM location in memory. Write AA and then 55 and see if any errors appear. Perhaps a simple ROM chip might help out here, use the strobes as the Address, and the Returns as the DATA. Run a Signature on the "address"? But how to specify the failing Strobe/Return line? Use the Walking bits test? Just some random ideas I'm afraid...

Looking in the Troubleshooter newsletter for an article on checking cables using a pod, for the switch matrix you already have all the select logic you are simply figuring out the test algorithm. Must re-read that more carefully.

Be sure to re read the Troubleshooter articles about the multi point prober.

Or you could just use the 9100 -003 module & strobe the I/O....I've still to try this idea but I'm pretty sure it should work.

As for you clip idea, what about 2 spring clips wired for AA & 55 for matching input buffers (245/244/367 etc?)

Kev