First post, by Kasreyn
Hi all,
I'm trying to bring an old 486 back to life that's been sitting in our basement, please help!
It just doesn't want to output anything over VGA, I've tried with either PCI or VLB ISA, "S3 Trio64" and "Trident TGUI9400CXi PM-V551 REV A"
The Trio64 tested OK in a MSI AGP system but the Trident I'm unsure about, do I need to touch the jumpers?
https://stason.org/TULARC/pc/graphics-cards/U … -VERSION-1.html
After some reading on vogons, it seems 486-VIP-IO2 is picky on PCI VGA.
I've done some steps towards troubleshooting, this is what I tried so far:
Voltage for socket 3, without jumpers in the regulator board it's 3.47V and jumpered for Cyrix it's 4.0V.
To get the readouts I followed https://www.dosdays.co.uk/topics/review_fic_4 … vip-io2_pt1.php
So it should give correct voltage for a DX4-100, it gets hot, but does that mean it's a good working CPU? A known good SX 33 MHz did not help.
Voltages for ISA, the upper ISA slot has +5V -5V -12V but I didn't measure the remaining pins.
Flashing a new BIOS:
The label on the BIOS IC says "486DX AWARD SOFTWARE INC. 5.12W2P 2857966"
Comparing the hex (dumped using XGecu Pro) the original BIOS has the same structure as 486-VIP-IO's "427gn2a.zip" BIOS.
The later "1175g701.zip" BIOS specifically for 486-VIO-IO2 do not have the same blank block in the beginning (0000-BFF0).
"427gn2a.zip" BIOS should work on either of these boards?
I dumped the original BIOS before flashing: http://opa.crabdance.com/bin/486DX-AWARD-2857966-5.12W2P.BIN
Other BIOS I've tried:
http://cwcyrix.duckdns.org/ftp-archives/ftp.f … -io/427gn2a.zip
http://cwcyrix.duckdns.org/ftp-archives/ftp.f … o2/1175g701.zip
Other things I tried:
- Removing the cache ICs
- Using a different PSU
- Changing the RAM (it has FPM RAM "NEC 424400") from just one stick to switching from BANK0 to BANK1 to all banks populated.
- Moving the jumpers around,
JV1 + JV2: 0/1 wait states &| "<= 33MHz" &| "= 33MHz"
J28 + JT1: "PCICLK = CPUCLK" | "PCICLK = CPUCLK/2"
J29: Monitor type select CGA/VGA
JC4: P24T/P24D cache type select write back closed/open
None of these things have really helped getting it to output anything over VGA.
Pictures of the board and GPU:
http://opa.crabdance.com/img/486-VIP-IO2-1.jpg
http://opa.crabdance.com/img/486-VIP-IO2-2.jpg
Jumper settings from manuals:
https://stason.org/TULARC/pc/motherboards/F/F … 86-VIP-IO2.html
download/file.php?id=21444
FPM RAM "NEC 424400":
https://classiccomputershop.eu/Webwinkel-Prod … -retro-90s.html