486 VLB UMC-Chipset, what is it?

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Re: 486 VLB UMC-Chipset, what is it?

Postby bnbjaj » 2017-8-17 @ 21:38

Gerwin, you are a life saver! Last week I scored an 486 system on Ebay. The motherboard simply stated MB456V1.1 which gave no google results. Then I searched the UMC chip set and hit the jackpot with this post. Your package for TK8498F motherboard and VGA+Multi-I/O gave me all the info I was looking for. It seems this UCM motherboard design is available with a variety of different markings on the board. As already mentioned in this post, my 486 UCM rig also includes the UM85C418 VGA/Multi-IO VLB board. Thanks a million for your detailed posts, it has become my 486-bible.
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Re: 486 VLB UMC-Chipset, what is it?

Postby gerwin » 2017-8-22 @ 18:59

Good to hear that this topic was helpful for you. I suppose quite a few typical 486 problems and solutions were encountered during the tweaking of this 486. Makes me wonder, which problem did I miss out on. Well... Fake cache for example ;).

If you have time, please share some more details and/or photos of the system you obtained. I wonder what the CPU it came with, and wheter or not the VRM is present. Also, are you planning to use it as it is, or do you want to upgrade parts of it?

Yesterday I slightly updated the package on vogonsdrivers: Corrected typos in the CPU jumper table, Put the right jumper setting for 20MHz FSB in the layout and removed the duplicate VGA manual.
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Re: 486 VLB UMC-Chipset, what is it?

Postby bnbjaj » 2017-9-10 @ 13:05

The 486 was extremely dusty. I did not take any pictures when it came in. I bought it because I needed the VLB video card, controller card and audio for another board. After I found this post, I played with the MB for a while, trying out some combinations of RAM, CPU and cards. In the end I put it aside due to its multiplier limitation. It came originally with an Intel 486DX2-66 S (heatsink glued to the CPU) but in the end I used an AMD 80486DX2-80. If found one lying around but, it too, had the heatsink glued. Since AMD does not mark the bottom for these CPU's I pried loose the heatsink but it took some of the top surface with it. With the help of cpu-collection.de I figured it was an AMD A80486DX2-80NV8T.

Here is the motherboard with the original 486DX-2 66-S. I had already removed the 2x8Mb EDO and replaced it with double sided 2x32Mb EDO. Cache shows all banks 32Kx8 20Ns for a total of 256Kb.
BAE73321-36C1-481C-B338-C6E89146A633.JPG


Backside of the CPU
A714F102-1AF1-4B1A-889E-B771FED2F112.JPG


Board marking
8990706E-D99B-4854-8CDC-81D8B866E862.JPG


TK85C418GVIO-4J-D08 for which I found the jumper settings in your documentation! I disabled the HDD/FDC as it was not stable and used a seperate VLB I/O card.
This card ended up on the other 486 board (ZIDA 4DVS, AMD486DX4-100)
4B04502E-6FFC-4794-99FE-D0542D8B35B1.JPG


The Cirrus Logic GD5422 I used for the benchmarking
5134C443-A7A4-407A-88D5-39DC65195087.JPG
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Re: 486 VLB UMC-Chipset, what is it?

Postby bnbjaj » 2017-9-10 @ 13:34

Continued:
The I/O board used for the benchmarks. It's an UMC card with UM82C863F/UM82C865F and branded MIO-VL P103.
1026BA9A-4E98-4178-A596-0AB1CFEB500C.JPG


The Crystal CX4235-XQ3 that also ended up on the new board. I was unable to get it working in pure DOS. No issues with WIN95.
D09A8F29-54D5-4A94-A693-C58856254FDA.JPG


The AM486DX2-80 after I removed the heatsink. It's the AMD A80486DX2-80NV8T as it has the 'N' is barely visible under X. In addition it shows the 'B' under A80, which is part of the B 9520 APD T marking.
F7FDD747-B516-4CB4-98E4-CD1B38974DAF.JPG


AWARD BIOS
AE910ADF-3090-4F30-9145-65D63249DB2B.JPG


Excellent jumper markings on the board
37F8EF66-7F53-4B70-977C-2B7E64583461.JPG
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Re: 486 VLB UMC-Chipset, what is it?

Postby bnbjaj » 2017-9-10 @ 14:05

Continued:

Test setup: I used an ATX power supply with the ATX-to-AT connector, a CF card for DOS 6.22 and benchmark programs, the AT-to-PS2 Keyboard adapter and a passive heatsink on the AMD486DX2-80.
31C5B7EC-941B-4338-B083-3BBD3B17A023.JPG


VOGONS has an awesome collection of benchmark programs. A big Thank You to Phil and others for initiating and uploading these. As I am rather lazy than tired, I simply use Phil's DOSBENCH which I downloaded from his site.

Results:
Results.JPG


95B93694-D216-4034-A377-CC7CCFE4DBA8.JPG


Although the battery clearly needs replacement, it doesn't leak and after a couple of hours of operation seems to gather enough energy to retain changes in the BIOS for a couple of days. So, if I use the board regulary, there is no need to setup the BIOS each time I start the machine. It's a fun board and I am happy to have it in my collection.
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Re: 486 VLB UMC-Chipset, what is it?

Postby bnbjaj » 2017-9-10 @ 14:57

Forgot: as can be seen above, I was playing with Write Back and Write Through. Speedsys 4.78 above shows the WT results. With WB the outcome for Speedsys is slightly higher. In the Excel overview different outcomes show and not all results are higher for WB.

Speedsys for WB
IMG_7822.JPG


After tweaking the BIOS a bit more, all WB totals got even better.
IMG_7823.JPG


Speedsys for WB after BIOS tweak.
IMG_7824.JPG
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Re: 486 VLB UMC-Chipset, what is it?

Postby gerwin » 2017-9-15 @ 20:04

Thanks for sharing these good photos and the background story!
Funny that it came with EDO SIMMS instead of FPM.
The Crystal CX4235-XQ3 card should work fine in DOS. Like with this set of Drivers. But this particular CS chipset has malfunctioning FM music, or so I was told.
I actually gave up on Write-Back cache. It was unreliable and also 'Anonymous coward' mentioned that WB does not work properly with VLB in general.


Two questions:
-What do you mean with "its multiplier limitation"?
-Did you use the original BIOS?, would it be possible to make a BIN file of the BIOS?
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Re: 486 VLB UMC-Chipset, what is it?

Postby Cga.8086 » 2017-11-08 @ 20:00

how do you install a intel dx4 1000 on this board TK 8498F ?

the manual does not say anything about dx4
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Re: 486 VLB UMC-Chipset, what is it?

Postby gerwin » 2017-11-09 @ 01:16

I used the settings from Total Hardware '99 for the identical board F4DXL-UC4. All is in the package I uploaded to vogonsdrivers before.

Code: Select all
CPU Type     JP11         JP12         JP13     JP17     JP18     JP19     JP20
AM486DX4     2-3          2-3          1-2,3-4  1-2,3-4  1-2      Open     Open

Note that the above does not match the silkscreened settings for P24C, which is the DX4 codename.
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