Branden wrote...
In the first place, I think my assumption of it exposing a large rom was wrong, it looks like they only actually only expose a small amount as regular bios boot rom space. While that sounds annoying, it would probably still be workable though.
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I'm hoping that somebody still remembers a bit about them and maybe knows something about how I can get the chip working, confirm that it's not working, or just tell me I'm doing it wrong.
It has been a long time since I have used one of these (and never with coreboot) but from what I remember the device needed something like 16KB in the expansion ROM area (between 640KB and 1MB).
The DiskOnChip contained firmware that was executed as a BIOS extension / option ROM. For DOS based systems the firmware hooked onto int 13h (disk services) so that it got allocated a drive letter and also handled the the flash paging / erasing / reading / writing. I used devices with capacities ranging from 2MB to 256MB and they all only needed the same amount of space in the ROM area. My first question… what have you plugged the DiskOnChip into? Is it a motherboard that was designed to accept them or is it a plug in card with a ROM socket on it? (M-Systems initial evaluation board was an ISA card).
As you tried to do, I would start with DOS as it is a more simple environment to play in. I would also start with a BIOS that has legacy ROM support in it. Check as it boots for messages relating to M-Systems and DiskOnChip. If there aren’t any of those then use DOS debug to look through the expansion ROM area and make sure you can see the firmware.
Once that is working, move on to coreboot, Linux or whatever other combination you want to use with them.
-Andy.