VLSI 82C840 486 chipset: anyone seen a working UMB driver? \ VOGONS

VLSI 82C840 486 chipset: anyone seen a working UMB driver?

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First post, by keropi

Posted on 2019-08-10, 10:03

keropi Offline

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Hiya!

Yesterday I received a nice IBM PS/1 486 tower , model 2168-552. This system uses the VLSI 82C480 chipset (datasheet download) :

supposedly The Last Byte supports it and have it on it's list but auto-detection fails and if forced to use it the system freezes.
I can see the UMB area is mostly not used - plenty of space for ram to exist there. Obviously I want to create and use UMB blocks without using EMM386 or a similar EMS memory manager.

If anyone has an idea or suggestion please comment, thanks!

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💻 WTB Amstrad PC7486SLC-33 system

Reply 1 of 4, by keropi

Posted on 2019-08-10, 17:41

keropi Offline

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added the chipset's datasheet just in case more knowledgeable people see something relevant in there 😀

🎵 PCMIDI mpu site buy+info
🎧 WIP Orpheus soundcard site
💻 WTB Amstrad PC7486SLC-33 system

Reply 2 of 4, by keropi

Posted on 2019-08-10, 22:32

keropi Offline

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with Tiido's input we poked the chipset on system about it's version and apparently it has a different product code meaning a -FC1 datasheet is needed (which ofcourse is nowhere to be found as expected 🤣). This is what the system reports , it seems the changes are enough to mess with TLB

🎵 PCMIDI mpu site buy+info
🎧 WIP Orpheus soundcard site
💻 WTB Amstrad PC7486SLC-33 system

Reply 3 of 4, by Deksor

Posted on 2019-08-11, 10:32

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Maybe you can tinker with UMBDRVR ( http://www.win3x.org/win3board/viewtopic.php? … =30&f=8&t=26070 )
I'm not sure if I'm getting the documentation properly, but I think you can use more than the listed chipsets by doing something)

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