5500 board won't POST/chime w/o the Display hooked up?

[Trash80toHP_Mini]

I've got a test rig that'll boot Alchemy and Gazelle boards, but not my AIO 5500 sub-variant of Gazelle. Does it fail to POST due to lack of internal CRT hookup or might there be another issue with this particular board?

If display is indeed the problem, will it POST with the external display/projector cable in lieu of the A/B CRT hookup?

 

[joevt]

Is the 6500/TAM emulation of DingusPPC good enough to test this? It might be missing some stuff that makes the emulated machine identify itself as a 5500 AIO if such stuff exists.

Would need to compare dump-device-tree and DumpNameRegistry and System Profiler and UnivTables low memory globals.
https://68kmla.org/bb/threads/skipping-the-startup-memory-test.50699/post-570896
https://forums.macrumors.com/thread...l-work-in-a-beige-power-macintosh-g3.2303689/
https://68kmla.org/bb/threads/how-does-the-l2-cache-work-on-nubus-powerpc.47395/post-572444

 

[Trash80toHP_Mini]

Hi, Joevt, hoped you'd join in here. Just rebuilt the TestBed and have successfully tested 6360/6400 boards but haven't located my 6500 board. I'd though I might have corrupted my CF boot disk, but it was the reader that died?

My first thought was that there might be some machine ID setup on the board to blame for this like the 475/605 twiddler? That's the only way I can think of offhand to make the 5500/6500 fork in the road before POST hits ROM?

Looking for my 6500 board to backcheck the situation.