I've got a few different ISA soundblasters, all of the PnP variety, so this new one is a unique in that it's purely jumper driven. I managed to pick it up locally fairly randomly on an 'untested' basis. Fortunately plugging it in everything seems to be perfect with the exception of the speaker out …

So turns out the system *will* not boot off floppy if the compact flash is connected and bios shadowing is disabled. It just hangs after the memory test (though responds to ctrl-alt-escape, to enter bios setup). The times I have booted this way seem to have been a case of the bios being buggy and …

Just as an aside as I try to figure out how this works at a low level, The address I'm peeking at in memory is effectively the 4 byte value at INT 41H in the Interrupt Vector Table? So, if I want to look at the FDPT for drive 2, I'd use INT 46H and therefore something like this in debug? D 0:118 L 4 …

Thanks again for your help Jake - the computer will boot from floppy, indeed if I put the compact flash on a secondary channel, or as a slave it will boot into windows. The compact flash drive is detectable, it will show up in windows 95 and dos, however if you try and write to it, or read more than …

Apologies for these photos not being super clear camera seems to catch the refresh. Basically both drives detect fine on auto and determine correct CHS settings. Only difference is when bios shadow is disabled the compact flash will not boot (but is detected correctly in bios). This bios is …

Running into a strange problem with my 486 project, I have a 486DX2V (the desktop rather than tower version) which comes with a Micronics DXLB mainboard. After a lot of wrangling I managed to get a 512MB (485 MiB) compact flash drive to work with the onboard IDE (and an ISA multi io IDE board) and …

I read this somewhere and was trying to find the link to where I'd seen it, but yeah the second dip socket was either labelled even BIOS or the original RAMDAC. Glad you got it sorted! That said, these kinds of debugging hijinks and occasionally eureka moments are why we do this right!?

Looking at the board diagram at http://ps-2.kev009.com/ohlandl/video/ATI_GUP.html, it would appear to be for odd/even bios addresses. Look at U17/18. Perhaps the earlier revisions didn't need that since they only had the one RAMDAC the newer ones had to support two types?

Trying to find a site that had a nice breakdown of all the parts on the Graphics Ultra Pro that specifically labelled that empty socket. One other thing to note, it's interesting that the earlier revisions of the GUP have fewer traces on the VLB connector, note mine is missing a bunch compared to …

Sorry for the delayed reply here - that second dip socket (the one you have, and mine is missing) is the original RAMDAC. You've put your new one in there, so you could try removing it and see if that stops the strange behaviour? A full shot of my card is attached, note my empty socket above the …

Thanks for the reply, I'm just starting out with this machine. I'll get a full idea what sort of Mach32 I've got though it looks like (from the BIOS at bootup) it's P/N 113-19500-100. *Edit* chip shot attached.

I ordered a tube of TC524258BZ-80 TOSHIBA 28 PIN ZIP 256Kx4 chips for an old MACH32 Vram card. Hope it works. I've gathered that the ATI 68875 ramdac may be compatible with a TI TLC 34076-135FN -- http://www.tavi.co.uk/ps2pages/ohland/GUP.html I can't find any affordable version of those, but I see …