Carrera SE30 control and Bolle Carrera040 in the Mac SE/30

[zigzagjoe]

Note that issue only occurred on the reloaded board - if you don't have a reloaded board with a socketed FPU, I wouldn't suggest desoldering it. Instead I would try installing the stock ROM rather than the aftermarket one.

 

[croissantking]

Note that issue only occurred on the reloaded board - if you don't have a reloaded board with a socketed FPU, I wouldn't suggest desoldering it. Instead I would try installing the stock ROM rather than the aftermarket one.

This is a new one to me, is it a Carrera + HC Video 30 card + aftermarket ROM issue, or just a Carrera + aftermarket ROM issue?

EDIT: Ah, found your answer to this

Also how could it just affect the Reloaded board since it’s electrically identical to the original?

 

[zigzagjoe]

This is a new one to me, is it a Carrera + HC Video 30 card + aftermarket ROM issue, or just a Carrera + aftermarket ROM issue?

EDIT: Ah, found your answer to this

Also how could it just affect the Reloaded board since it’s electrically identical to the original?

Multiple factors in play here, but the suggestion to remove the ROM is based out of most of the third party ROMs having lower drive than the original ROMs, between that and software changes it's adding additional variables to the equation. That said I'm not aware of any particular incompatibilities between those combinations of ROM and expansion cards.

The post you linked is specifically from the original 30Video cards with the passthrough slot, but it does have some relevance here. Best guess there was some odd termination/reflection issue resulting from the extended system bus and nothing on the passthrough slot. The "fix" was a mystery pulldown resistor on /DS which has been retained on all subsequent designs. Carreras drive the system bus directly off the FPGAs and as I recall @Bolle noted them to be somewhat picky about RAM also so the assumption is this issue is in the same family as that.

While the Reloaded board is identical at the schematic level the actual PCB layout differs meaning trace capacitance / length / noise characteristics will also be different. That shouldn't matter, but considering that particular issue Carrera is well into "weird voodoo stuff" territory, it seemed to help @codevonlux's setup. Removing the FPU would reduce the load on the bus slightly even if it isn't used while the 040 is in play, seemingly it was enough in that particular scenario. My socketed carrera didn't have this issue either so it appears to be just a particular edge case.

I don't think it's any issue of the reloaded board design just a quirk of the Carrera. So I don't recommend pulling FPUs off original SE/30 boards given there's no guarentee it'll do anything productive. Also, they're typically soldered and the stock ROM will have issues booting without one.