AST Sabre MFP+ LB 486 System - Information Requested \ VOGONS

AST Sabre MFP+ LB 486 System - Information Requested

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First post, by legodude

Posted on 2024-08-18, 01:50

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I'm still failing in my search for a 486 microchannel system, so I ended up with another 486 ISA system to tide me over. It is an AST Sabre MFP+ LB. I can't find much information about this system anywhere - it is not listed in The Retro Web. It has a 486sx on the motherboard, with a Socket 2 ZIF for upgrades. The cache upgrade module is present. There are 4x 72pin RAM slots. Onboard graphics are VLB ATI MACH32 with 1mb video ram on-board, and two open sockets for more VRAM.

There are 4x ISA slots on the riser.

BIOS 1.01
CMOS battery is a CR1025

Video memory chips are MT4C16260, 256k x 16 DRAM, 70ns. Finding exact chips to expand the video memory does not look to be easy.

If anyone has a BIOS update, manual, or source for compatible DRAM chips, please let me know.

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Reply 1 of 8, by legodude

Posted on 2024-08-23, 00:38

legodude Offline

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I did some trial and error, and discovered:
E13: 1-2 socket CPU, 2-3 built-in CPU
I don't know what the other jumpers do yet, but being able to put in a DX2 66mhz was my main goal for now.

Reply 2 of 8, by Horun

Posted on 2024-08-23, 02:37

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Ok I checked Ari Service (covers AST from 286 thru Pentium 200) and cannot find anything with Sabre in the name....need the actual computer part number not the board number AFAIK

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 3 of 8, by PC Hoarder Patrol

Posted on 2024-08-23, 03:40

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There's a manual listed for it on WorldCat and three files in the GRiD directory on SandyFlat.net (also on ARI) for the MFP+ L series (no mention of Sabre)...Windows video driver (seem to be for S3 rather than ATi), a BIOS update??? and a video mode switching utility.

Reply 4 of 8, by Horun

Posted on 2024-08-24, 03:30

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Checked the WorldCat info and the link is to Library of Congress which only has a record of the manual, not an actual viewable manual (is like a ISBN recorded number but not having the book, afaik).
Found no other info. Really need that computer part number that board came from to seek out more info.

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 5 of 8, by legodude

Posted on 2024-08-30, 15:22

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Motherboard part number is 202590.
I did image the bios.

Reply 6 of 8, by legodude

Posted on 2024-08-30, 15:30

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Reply 7 of 8, by legodude

Posted on 2024-08-30, 22:44

legodude Offline

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As purchased, there was a 33mhz 486SX and 16mb of ram. I have a 50mhz DX2, and as I mentioned above, I was able to figure out the jumper configuration to enable the CPU upgrade socket. I was not able to figure out which jumpers control bus speed, so the 50mhz DX2 was always overclocked to 66mhz, and would inevitably crash. I snagged a 66mhz DX2 from Ebay, and installed that tonight. It seems stable now.

As is now:
66mhz 486mhz DX2
256K cache module
16mb
NE2000 w/XTIDE
SD-IDE adapter
PicoGUS

I get about 23FPS in Doom (Phil's benchmark pack). I need to figure out if the Mach32 is actually VLB, or is ISA.

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Reply 8 of 8, by legodude

Posted on 2024-08-30, 22:46

legodude Offline

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PC Hoarder Patrol wrote on 2024-08-23, 03:40:

There's a manual listed for it on WorldCat and three files in the GRiD directory on SandyFlat.net (also on ARI) for the MFP+ L series (no mention of Sabre)...Windows video driver (seem to be for S3 rather than ATi), a BIOS update??? and a video mode switching utility.

Yeah, I had found those files, and they don't seem to apply to my system. I believe the BIOS update is just the flashing utility. I've not tried the video mode switching app.

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