Recent content by sqpat

Yes, backfill involves pagination of the 0x4000 - 0x9FFF segment ranges (256k-640k). Not very many programs make use of this, it's usually OS-level/multitaskers that do it. Most programs using EMS just use the page frame. Or maybe I'm wrong here? Anyway, many EMS drivers don't support backfill...

I think backfill is usually for OS/multi-tasking level software. I don't know if it plays nice with DOS, but when I use backfill in my code I don't malloc or request from the OS, I just use it :) Just have to make sure to unmap that memory when you are done and return to COMMAND.COM.

This driver here: https://theretroweb.com/motherboards/s/jetway-jet-386sx#bios has a couple more features and seems more stable than the commodore sx-25 award bios. It seems to be the 'best so far'. I tried a few other bios that would not properly POST due to A20 issues. Most of the rest are...

Some progress: I tried the Award BIOS found here: https://theretroweb.com/motherboards/s/dtk-ppm-2563v#bios which is from a 386sx SCAMP DTK board (same as the EMS driver). I tried it in my Biostar 386sx board, and it had options to set EMS/XMS (but honestly not a lot else). I was able to get...

Hmmm.. Looks like I can't edit the post anymore. Haha. Perhaps there is a maximum edit duration for posts on vcfed, I did not realize that.

The ega spec and initial card by ibm specify that the connector goes directly to some of the feature connector pins. I forget the exact details. But I don’t think it was a popular feature and so presumably some manufacturers eventually broke spec (like with other features like the light pen)

So I was organizing and cataloguing things in the collection today and found another scamp 386sx (!). Well, I gave it a try, and it has the same bios options as the 286, and also has all the same problems. Once I have some 512k eproms delivered, I will try some different BIOSes. There is an...

I got ahold of a 386sx based scamp board, also made by biostar. (I wanted to keep things pretty similar) After fixing the keyboard connector, I tried to get EMS working on it. So this board's BIOS had a new page of options. My eyes lit up when i saw "Slot Pointer" there. Slot pointer is...

This angelfire link and this software linked to on the page. I don't know about the IBM software but some google searching indicates there was some compatible software called ASYST made by MacMillan.

Buddy... sorry to disappoint you, but this post is 14 years old... shortly after this post i traded that adapter for a thunderboard sound card to another member, sold my whole collection, changed jobs, moved across the country and across the world twice, changed jobs a couple more times...

Yes, UMBDRVR works. But it is an EMS simulator and does not use hardware, so it will be really slow (copying data back and forth, rather than remapping near instantly). If you don't have particularly high demands then it will be perfectly fine to get a program running, though.

Let say on a dual head card. EDIT: Alternatively, off a feature connector on the VGA card, but I feel like that wont be compatible with CGA?

I wouldn't imagine the composite circuitry on the cga card is complicated. Can it be generated via an adapter from the 9 pin? - Patrick

I actually asked this question in a retro computer related discord yesterday. I think there weren't any examples, but the difference between an AT bios and a XT bios is comparatively small. However a sufficiently advanced 286 (or later) chipset may have memory and cache and I/O controllers...

There do exist dual-head cards that support CGA, MDA, VGA, and EGA in a single card. They have a 9 and 15 pin connector and switches on the back to select video mode. It would require a reboot between video changes, but you also wouldn't have to open the computer up or anything. I don't always...