Deksor wrote on 2020-12-01, 14:58:

Yes, I have done that and amd 5x86 works on my rev 1.4

Oh 😀 nice to hear, im having a 1.4 version board laying around and always thought it cant run 5x86 😀 may I ask what BIOS version and jumpper settings are you using, are you running the amd 5x86 with 4 Volts?

I don't remember exactly, I have installed a AMI bios, probably the latest 1995 version (which makes sense since the 5x86 is from august 1995). As for voltage, I just ran it at 3.3V
Jumper settings are documented somewhere iirc. Take a look at elhvb.com.

THis is a 100% clone of the M912 so you can use the settings of it:
http://www.win3x.org/uh19/motherboard/show/572

Just for the heck of it, the elhvb page:
https://www.elhvb.com/mobokive/archive/pcchip … m912/index.html

Thanks! Should I use the Cyrix 5x86 jumper settings also for AMD 5x86?

No, the Cyrix 5x86 is a different chip (despite the name)

I know 😀 But I cant find the AMD 5x85 jumpper settings from the manuals inteded for V1.4 Boards

Can you not just look up the required voltage, fsb and clock multiplier settings for the chip then set the motherboard jumpers accordingly?

Should be able to jumper it as an Enhanced Am486DX2-66, or do it first as an Am486DX4-100, and then figure out which jumper is the multiplier and change it once you get it running as a DX4-100 first.

jakethompson1 wrote on 2020-12-05, 01:17:

Should be able to jumper it as an Enhanced Am486DX2-66, or do it first as an Am486DX4-100, and then figure out which jumper is the multiplier and change it once you get it running as a DX4-100 first.

The v1.4 is an odd one with original BIOS, according to Amptron it does not support the AMD DX4's but the PCchips manual does list the AMDXLT (which are write back versions) but does not list Enhanced Am486DX2-66
or anything similar as supported unless that is what they meant by AMDXLT.
I have gotten a AMD DX4-120 NV8T to work but it is a "write thru" cache, not a SV8B write back type with the original Award BIOS to work on a v1.4.
Need to get Deksor the v1.4 manual so he can look it over.

Horun wrote on 2020-12-05, 03:06:

The v1.4 is an odd one with original BIOS, according to Amptron it does not support the AMD DX4's but the PCchips manual does li […]
Show full quote

jakethompson1 wrote on 2020-12-05, 01:17:

Should be able to jumper it as an Enhanced Am486DX2-66, or do it first as an Am486DX4-100, and then figure out which jumper is the multiplier and change it once you get it running as a DX4-100 first.

The v1.4 is an odd one with original BIOS, according to Amptron it does not support the AMD DX4's but the PCchips manual does list the AMDXLT (which are write back versions) but does not list Enhanced Am486DX2-66
or anything similar as supported unless that is what they meant by AMDXLT.
I have gotten a AMD DX4-120 NV8T to work but it is a "write thru" cache, not a SV8B write back type with the original Award BIOS to work on a v1.4.
Need to get Deksor the v1.4 manual so he can look it over.

Maybe it's possible to hack the BIOS to get it to work. If you have the BIOS image I can probably find the table of known CPUIDs in it and tell you what it knows about and what it doesn't at that level. Is it something to do with earlier Am486es having a different pinout and later ones having a P24D-compatible one?

hi to all, i have a DX4-75Mhz, and i don´t find the jumper settings for this speed and motherboard version are 1.7, actually im using a 486DX 33mhz,
the DX4 processor warms up , but no video, i try to change the multiplier x3 and 25mhz speed with no luck.
tomorrow i will check the date Bios, im evaluate buy a 486 DX2 66mhz or go for the 5x86 133mhz, but i think for this last one i need to upgrade the Bios first.
thanks in advance.

RoyCopyCat wrote on 2021-02-14, 01:00:

hi to all, i have a DX4-75Mhz, and i don´t find the jumper settings for this speed and motherboard version are 1.7, actually im […]
Show full quote

hi to all, i have a DX4-75Mhz, and i don´t find the jumper settings for this speed and motherboard version are 1.7, actually im using a 486DX 33mhz,
the DX4 processor warms up , but no video, i try to change the multiplier x3 and 25mhz speed with no luck.
tomorrow i will check the date Bios, im evaluate buy a 486 DX2 66mhz or go for the 5x86 133mhz, but i think for this last one i need to upgrade the Bios first.
thanks in advance.

It runs at 25Mhz and 1X multiplier. It will not run if you set multiplier other than 1X because it internally sets the 3X based on the 1x board setting. It also requires you to set CPU voltage to 3.3v or 3.45v.
"Notes on sSpec SK047
Core voltage range 3.1V - 3.6V, SL enhanced version. Processor does not support write-back.
The processor requires 1x external clock."

jakethompson1 wrote on 2020-12-05, 03:40:

Horun wrote on 2020-12-05, 03:06:

The v1.4 is an odd one with original BIOS, according to Amptron it does not support the AMD DX4's but the PCchips manual does li […]
Show full quote

jakethompson1 wrote on 2020-12-05, 01:17:

Should be able to jumper it as an Enhanced Am486DX2-66, or do it first as an Am486DX4-100, and then figure out which jumper is the multiplier and change it once you get it running as a DX4-100 first.

The v1.4 is an odd one with original BIOS, according to Amptron it does not support the AMD DX4's but the PCchips manual does list the AMDXLT (which are write back versions) but does not list Enhanced Am486DX2-66
or anything similar as supported unless that is what they meant by AMDXLT.
I have gotten a AMD DX4-120 NV8T to work but it is a "write thru" cache, not a SV8B write back type with the original Award BIOS to work on a v1.4.
Need to get Deksor the v1.4 manual so he can look it over.

Maybe it's possible to hack the BIOS to get it to work. If you have the BIOS image I can probably find the table of known CPUIDs in it and tell you what it knows about and what it doesn't at that level. Is it something to do with earlier Am486es having a different pinout and later ones having a P24D-compatible one?

Sorry just saw this and put the board back in storage. Will try to get a BIOS image but think you could find one here:
http://www.win3x.org/uh19/motherboard/show/6821

Got the AMD 5x86 work on this board, jumpered as 80486DX2-66 except voltage of course (3.3v) and multiplier (JP31, jumpered as x2).
I did not even upgrade the AWARD Bios v4.50, Release 11/01/94', 11/03/94--2C4X6H01-00.
The CPU is reported as Am486DX4-120 at boot, but chkcpu detects an AMD x5 at 133.7 MHz, x4 multiplier, 33.4MHz bus.

I tried to jumper it as P24D (486DX2 rite back) but the PC does not POST. No beep, nothing. I will try with my POST debug card. So for the moment it works as write through for the L1 cache.

Performance is great, e.g. Descent with a very good framerate, much better than the DX2-66, Tombraider is almost playable - but I still prefer a PCI machine with a Voodoo Banshee for that 😉

jice wrote on 2021-05-01, 16:24:

Got the AMD 5x86 work on this board, jumpered as 80486DX2-66 except voltage of course (3.3v) and multiplier (JP31, jumpered as x […]
Show full quote

Got the AMD 5x86 work on this board, jumpered as 80486DX2-66 except voltage of course (3.3v) and multiplier (JP31, jumpered as x2).
I did not even upgrade the AWARD Bios v4.50, Release 11/01/94', 11/03/94--2C4X6H01-00.
The CPU is reported as Am486DX4-120 at boot, but chkcpu detects an AMD x5 at 133.7 MHz, x4 multiplier, 33.4MHz bus.

I tried to jumper it as P24D (486DX2 rite back) but the PC does not POST. No beep, nothing. I will try with my POST debug card. So for the moment it works as write through for the L1 cache.

Performance is great, e.g. Descent with a very good framerate, much better than the DX2-66, Tombraider is almost playable - but I still prefer a PCI machine with a Voodoo Banshee for that 😉

if you have a good vlb you dont need pci slot. i tried many pci cards with Cx5x86-amd 5x86.no difference.cpu is bottleneck for 3d gaming on socket 3 platform

Well I have a CL5428 VLB which is not bad (also a ET4000 but I cannot make it work and don't know how to troubleshoot), I can play TR in low res, but of course visually it cannot compare to the Voodoo Banshee (on a socket 7 processor though, so I'm wondering how it would go with a 486 class CPU, but I've got no socket 3 PCI board).

I have rev. 1.4 with DX2/66 @80MHz. Ordered Am5x86-133.

But I'm still unsure what bios to use? Newest AMI or newest Award? Somewhere read that newest AMI supports larger hard drives? What I have now detects 6.4GB HDD wrong.

I have a EPROM programmer.

dj_pirtu wrote on 2021-05-10, 12:20:

I have rev. 1.4 with DX2/66 @80MHz. Ordered Am5x86-133.

But I'm still unsure what bios to use? Newest AMI or newest Award? Somewhere read that newest AMI supports larger hard drives? What I have now detects 6.4GB HDD wrong.

I have a EPROM programmer.

Use latest Award bios.Im using it with AMD 5x86 4x33 cpu

I'll do that. Got one spare m27c256 chip.

Later need to get another bank 128kb cache and VLB display card. Surprisingly fast my Cirrus 5420 ISA-card @20MHz ISA-bus clock. Doom and Duke3D runs smoothly.

3Dbench 1.0c gives ~46fps.

Got it up and running with Am5x86-133. Jumpers are for DX2 and voltage 3,3V. If I put jumpers to 5x86-133 settings then it wont post at all. Cache is in write-trough -mode. Need to upgrade bios but I dont have eeprom eraser just yet. Newer bios fixes that cache mode to writeback maybe?

Wont overclock to 160MHz stable, doom benchmark will crash. Tried same 40FSB with lower multiplier and it works so 160MHz is the problem. I have heatsink & fan.