Anonymous Coward wrote:

I think you're confusing the am5x86 and the am486.

nope, it's specified right on the chip label. There's no jumpers or bios setting to toggle the write mode for this cpu.

Do you have a picture of this chip? I've never seen one like that before. The only thing I see on my 5x86 chips are the indicators for 55 or 85 degree tolerance.

Also, this page talks about the WT/WB modes of the 5x86:

http://web.inter.nl.net/hcc/J.Steunebrink/amd5x86.htm

Just got another ECS UM4980 motherboard...this time it's rev 2.1 instead of 1.0 which is in this machine.
Sadly they seem to have removed the option to set system speed in steps of 1/16 😖
And there's no built in voltage regulator for 3-5volt CPU voltage...you gave to mount a special voltage regulator board which is what I have on my ECS UM8810 board.

Have retired this machine.

Mobo is for sale if anyone is interested.

Will be selling it on Ebay in circa two weeks if I don't get a "bite" from someone here

Those are good boards. I gave away one just like it last week. Do you think they're worth much on ebay?

Anonymous Coward wrote:

Those are good boards. I gave away one just like it last week. Do you think they're worth much on ebay?

Was it a rev 1.0 like mine? only rev 1.0 have the variable slow down feature

I should be "valuable" to those who appreciate the slow down feature of this rare revision....I will have to advertise this feature when I sell it

That motherboard looks identical to mine except i have 2 x 72-pin simm slots next to the row of 30-pin simm slots.... apart from that it is pretty much identical!

Mine is now running:

Amd 486 DX4-100mhz.
32mb FPM 60ns RAM (2 x 16mb 72-pin simms).
1.6gb Fujitsu IDE hard drive.
8x Sony CD drive.
1mb Cirrus VLB graphics.
Winbond VLB I/O card (IDE, floppy and com ports etc...).
Sound Blaster Pro 2 (CT1600).
Windows 95/Dos 6.22

I could never identify the motherboard but now i'm guessiing it may be a later revision of yours with 2 72-pin simm slots added?

PowerPie5000 wrote:

That motherboard looks identical to mine except i have 2 x 72-pin simm slots next to the row of 30-pin simm slots.... apart from […]
Show full quote

That motherboard looks identical to mine except i have 2 x 72-pin simm slots next to the row of 30-pin simm slots.... apart from that it is pretty much identical!

Mine is now running:

Amd 486 DX4-100mhz.
32mb FPM 60ns RAM (2 x 16mb 72-pin simms).
1.6gb Fujitsu IDE hard drive.
8x Sony CD drive.
1mb Cirrus VLB graphics.
Winbond VLB I/O card (IDE, floppy and com ports etc...).
Sound Blaster Pro 2 (CT1600).
Windows 95/Dos 6.22

I could never identify the motherboard but now i'm guessiing it may be a later revision of yours with 2 72-pin simm slots added?

Are you sure it's an UM4890? is the model # typed on the board?

Amigaz wrote:

PowerPie5000 wrote:

That motherboard looks identical to mine except i have 2 x 72-pin simm slots next to the row of 30-pin simm slots.... apart from […]
Show full quote

That motherboard looks identical to mine except i have 2 x 72-pin simm slots next to the row of 30-pin simm slots.... apart from that it is pretty much identical!

Mine is now running:

Amd 486 DX4-100mhz.
32mb FPM 60ns RAM (2 x 16mb 72-pin simms).
1.6gb Fujitsu IDE hard drive.
8x Sony CD drive.
1mb Cirrus VLB graphics.
Winbond VLB I/O card (IDE, floppy and com ports etc...).
Sound Blaster Pro 2 (CT1600).
Windows 95/Dos 6.22

I could never identify the motherboard but now i'm guessiing it may be a later revision of yours with 2 72-pin simm slots added?

Are you sure it's an UM4890? is the model # typed on the board?

This diagram looks like mine which also looks quite similar to yours: http://artofhacking.com/th99/m/A-B/33259.htm

Here is a photo of the exact same board i have: http://farm1.static.flickr.com/236/455596555_ … 9e8c7bc.jpg?v=0

The Bios string is: 02/28/95-UMC-498GP-2C4X6U01-00 (Award Modular Bios v4.50G) and it has the model number "JK-042A" printed on the board.

The one I had was UM4891. It seems to be the same except with integrated I/O

Amigaz wrote:

Have retired this machine.

I'm curious, why did you retire this UM4980 mobo? Did you find that although it had the 1/16 BIOS speed stepping functionality, using it wasn't as effective as a real 386? I just spotted a UM4980 mobo on ebay, but it might be the version without the 1/16 BIOS speed stepping functionality. It's here.

Also, on a different topic, while browsing ebay I was quite shocked that the seller BlackmoreIT managed to sell an old Viglen 486 mobo for £100! That's over $US 160. I have one of these mobos, and its Dallas RTC is soldered on to it, and also I could not get it to POST. It's here.

retro games 100 wrote:

Amigaz wrote:

Have retired this machine.

I'm curious, why did you retire this UM4980 mobo? Did you find that although it had the 1/16 BIOS speed stepping functionality, using it wasn't as effective as a real 386? I just spotted a UM4980 mobo on ebay, but it might be the version without the 1/16 BIOS speed stepping functionality. It's here.

Also, on a different topic, while browsing ebay I was quite shocked that the seller BlackmoreIT managed to sell an old Viglen 486 mobo for £100! That's over $US 160. I have one of these mobos, and its Dallas RTC is soldered on to it, and also I could not get it to POST. It's here.

As a 486 system it wasn't very "exiting"
I wanted something more "solid" and of better quality so I built three 486 machines based on Eisa motherboards made by Everex and ECS.

Going to sell this UM4890 mobo someday, it's only the rev 1.0 that has this "speed" function in the BIOS