View Full Version : PC/XT Xebec MFM Controller & ST-412 in P200

June 14th, 2013, 05:11 AM
Hi, I tried to get the above working but it seems to hang at the end of the POST. The machine does respond to CTRL-ALT-DEL. I tried disabling processor caches and setting all IRQ/DMA resources to ISA, but without any luck.

Any ideas?

June 14th, 2013, 09:06 AM
What chipset does your P200 use? I'm not optimistic about this sort of thing working, but it's worth a try. If you pull the controller BIOS chip, will the system boot?

June 14th, 2013, 09:38 AM
Chuck, thanks - I'll check. Controller BIOS expecting other PC/XT components, are you thinking?

June 14th, 2013, 10:26 AM
No, more likely a difference in BIOS conventions. ISTR (buf haven't checked) that the XT hard disk controller uses 32xh as its port addresses, so that should be in the clear.

Some later chipsets claim to support ISA, but the DMA support is either nonexistent or quirky. At any rate, I think I have some ancient code here that uses an XT controller without touching the BIOS--it might point up whether what you want to do is possible at all.

June 14th, 2013, 12:59 PM
That would be very helpful if you can find it! I know that DMA support works, 'cause I used the machine to develop the XT-CF DMA :)

June 18th, 2013, 10:00 PM
I found my test code; unfortunately it looks for either a standard AT-interface controller and then, if that's not found, an XT-interface controller and uses whichever it finds, but not both. Since you're running in a P200 with an integral IDE controller, the code will never get to checking for the XT variety.

However, I think I might be able to modify the code. Do you still need it?

June 19th, 2013, 01:13 PM
Hi Chuck, thanks. I don't think I'll have the time to do much with this unfortunately, but thanks for looking. It was only for my latest blog post (http://www.lo-tech.co.uk/shugart-and-the-bubble/) anyway :)