PowerBook 1400 series ROM and RAM tidbits

[croissantking]

This week I've been getting my PowerBook 1400c to work with a 166MHz CPU card. To do this, I installed newer ROMs from a donor 166 board, and this has been successful.

While I had the 2 revisions of ROM chips off the boards, I dumped their contents with my T48 programmer, and have attached here if anyone is interested in comparing their contents (@David Cook maybe?).

Meanwhile the donor board, which now has the old ROMs, has a problem that I'd be interested in resolving. It won't let me install more than 56MB RAM. If I try to fit 64MB, it will display an error during extensions load - 'The built-in memory test has detected a problem' - and then disable some of the memory. The thing is, it's not one single RAM module it has an issue with, because all memory works fine so long as it doesn't need to count past 56MB. And the same modules all work together in my other board for 64MB total.

I noted this advisory on everymac.com:

A maximum of 56 MB of RAM is possible with the 16 MB of onboard RAM, one 24 MB memory card and a second 16 MB memory card. Curiously, unlike the slower PowerBook 1400cs/117 and 1400c/117, installing two 24 MB memory cards will not work and will result in a memory test failure at startup.

Has anyone else experienced this issue?

Both boards are recapped.

 

[Snial]

Curious. My PB1400c/166 (sorry old bean), has 56MB from 8MB Mobo RAM + 8MB System RAM + 16MB +24MB user RAM modules. So, I can't really prove or fix that issue (I do have another 8MB System RAM module and there are 4 spaces for RAM on my 24MB module, or maybe the 16MB one. But I don't know if the 8MB is reliable anyway. I'll have to swap the System modules to check that).

 

[eharmon]

Interesting, the 166MHz ROM is checksum 838C0831. I don't think that's a previously known dump, at least!