SE/30 + dougg3 rom simm testing help requested

[techknight]

Would be awesome, because I dont think anything is still quite nailed down yet. 

 

[james_w]

OK, I may have some time to do so this weekend...

 

[Macdrone]

So I have a SE/30 put in 128 megs of ram and it boots and shows 128 megs of ram, with no pram, shouldnt Ihave to switch to 32 bit addressing and reboot?  The memory control panel wont show 24 bit if it was 32 bit clean rom right?

 

[Kazu]

I have used my SE/30 with 128MB RAMs and a stock IIsi ROM too.

As far as I recall, sometimes control panel shows 32 bit and sometimes it won't (have to switch to 32 bit).

I don't know why.

 

[rsolberg]

Macs with 32-bit clean ROMs can still run in 24-bit mode under System 7.0-7.5.5. As far as I know, all will revert to 24-bit mode if PRAM is reset. Normally, all of the RAM is shown in About this Mac, but System will be "using" everything beyond the addressing limit, leaving only a fraction available. The SE/30 logic boards and perhaps original ROMs seem to be fickle when it comes to higher density RAM, so the amount of RAM detected may be less than is is installed. if that's the case, the wrong amount seems consistent between 24 and 32-bit modes.

If System 7.6 or newer are installed, 24-bit addressing is unavailable. A 32-bit clean ROM is required, and the system will boot in 32-bit mode even after a PRAM reset.

 

[fimbulvetr]

 The SE/30 logic boards and perhaps original ROMs seem to be fickle when it comes to higher density RAM, so the amount of RAM detected may be less than is is installed. if that's the case, the wrong amount seems consistent between 24 and 32-bit modes.

Well, that would explain why my SE/30 only reports 28 mb RAM when 32 mb is installed. This has been bugging me for a while now. I wondered if it was a bad simm, but swapping each in turn with a known good simm didn't help, and the computer functioned fine. Would a 32-bit clean ROM fix this?

 

[olePigeon]

My own testing confirms rsolberg's assertions.  The SE/30 seems to be very picky about the RAM in terms of speed and density, especially when using the dirty ROM, and especially when using Bank A (first 4 RAM slots.)  When using a clean ROM, it likes to have same-speed RAM.  From my own experimentation, the only way to use 16MB SIMMs is with a clean ROM.