On Sun, Jan 22, 2017 at 5:16 PM, Jon Elson <[email protected]> wrote: > On 01/22/2017 10:07 AM, Ali wrote: >> >> Al, >> I thought the problem with switching these chips was that part of the ROM >> code was embedded in them? I.e. it isn't just an issue of battery? Am I >> wrong? If I am then why not use one of the replacement chips that are >> available? >> > These don't have a lot of memory on them. many early PCs stored some config > info there, but generally the BIOS can reconstruct it if it isn't there. I > suppose there is a possibility that random data in the CMOS memory could > cause the BIOS to try to use unavailable features and hang. I don't think > anybody put actual executable code in there.
On most PCs the RTC chip is mapped as I/O ports, not memory, so you couldn't execute code from its RAM anyway. I suppose on (say) a 68000 based machine you could (there is no separate I/O port address space on that processor) but I have never seen it done. -tony
