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

Trash80toHP_Mini

Trash80toHP_Mini

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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?
 
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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
 
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.
 
Won't the board need to at least power up to play with whatever you call communicating at low level over a serial connection? Dug my 6500 board out of the Classic it's been sitting on its head in for two decades. It powers up/chimes, but no video out for some reason. I'll dig out the proper two story Video Out/Sub driver variant and see if that makes a difference, doubtful, but another base to cover.
 
Trash80toHP_Mini said:
Won't the board need to at least power up to play with whatever you call communicating at low level over a serial connection?
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Yes. You are able to do that by connecting a display?

Get into Open Firmware, do the probe-ids. Disconnect the display while still in Open Firmware. do probe-ids again. We'll see if there's a connection between the ID's and the display connection.

What does failure to post look like? no startup chime? I wonder if it enters the Serial Test Manager?
 
Trash80toHP_Mini said:
No video out from a PCI card either, so it's hanging somewhere before either of the paths to video dsiplay are initiated.
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I guess I misread the original post or the thread title. I thought it was booting with a display connected somehow.

You're not seeing anything from the serial port?
What does failure to post look like? no startup chime? I wonder if it enters the Serial Test Manager?
Maybe you need a bus analyzer that can read what addresses the CPU is loading instructions from.
 
They're both chiming now so I'm not sure which is which. Neither produces video or hits the CF Card, so they're hanging fairly early on during POST I'd think.

Test setup is now my re-built as of today, 6360, works great with the Alchemy boards. I've never messed with the serial port stuff.
 
Trash80toHP_Mini said:
I've never messed with the serial port stuff.
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If it's doing the system chime then it might be able to reach Open Firmware (Command Option O-F) or the Serial Test Manager (some POST error might cause it to automatically enter the Serial test Manager). Either one will require a serial connection to the modem port to check. You'll need a serial crossover cable (usually a serial printing cable such as for an ImageWrite II).

For some serial port notes, search for serial in the first post at:
https://forums.macrumors.com/thread...l-work-in-a-beige-power-macintosh-g3.2303689/

Some Serial Test Manager notes:
https://68kmla.org/bb/threads/skipping-the-startup-memory-test.50699/
https://68kmla.org/bb/threads/the-820-0961-a-mystery-g3-3-3v-flashrom.48746/post-548608
https://tinkerdifferent.com/threads/new-diagnostic-tool.4593/post-39652
 
HRMMM, sounds like something to try if a recap doesn't fix them.

@defor came up with something when I mentioned the Gazelle boards rolling their own 3.3V power:
"they provide SOME 3.3 but it’s not enough current to run most cards from what I remember… like it’ll boot but adding some cards will be too much for the onboard regulation."

Wondering if adding a 3.3V regulator to one of the Gazelle boards might do a nice dirty little trick befor the recap option? Does POST check power levels and if so, when in the process?
 
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