Horun wrote on 2020-03-12, 22:27:

I was thinking something like a Zenith or DEC system. The dual P5 in this thread NEC Proserva V Plus (dual socket 7 system) (hav […]
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quicknick wrote on 2020-03-12, 21:06:

The PSU is from a branded system, for sure. It probably has only the connectors that were needed in that system.

Edit: after a quick search, it seems the PSU for the AcerPower 4100.

I was thinking something like a Zenith or DEC system. The dual P5 in this thread NEC Proserva V Plus (dual socket 7 system) (have a lead on multiple of these)
has a similar (but differant) special PSU lead to the board, then the board header has Power switch, reset and LEDS connections to front panel.
Finding the proper PS-On wire using a 22ohm resistor is a good idea. Being a 486 board 200watt PSU is more than enough...

It's funny, you find a lot of High Power HPC-200C2 PSUs on ebay.
But there is NO info for what kind of PCs they were made 😁

Success! Well... partially. I did the paperclip trick with the white and ground wires on that connector, and the PSU powers up! All the rails on the P8 & P9 look correct on the multimeter. However, nothing beyond that - just a blank screen. CPU started to get warm... so I guess that's good. I'll probably have to mess around with the jumper pins while deciphering the limited documentation I have on the board before I get anything on the screen.

I expect I'll be back on here with questions very soon. Thank you all for your help.

evildave9000 wrote on 2020-03-12, 23:45:

Success! Well... partially. I did the paperclip trick with the white and ground wires on that connector, and the PSU powers up! All the rails on the P8 & P9 look correct on the multimeter. However, nothing beyond that - just a blank screen. CPU started to get warm... so I guess that's good. I'll probably have to mess around with the jumper pins while deciphering the limited documentation I have on the board before I get anything on the screen.

I expect I'll be back on here with questions very soon. Thank you all for your help.

Great ! Hey you need parity ram, the ones in the picture do not look right. If you have true 9 chip simms try them first, if not then one with 3 chips one side or per side). Be sure to hook up a speaker to the board so you can hear beeps.....

Hi Horun - The manual I've found online says it supports parity and non-parity. I don't really understand memory configurations too well, and having read through the manual again, I'm not much clearer. It says:

"Mix 256K, 1M, and 4M SIMM (8 bit/32 bit) Module DRAM memory"

So that would mean my 8mb sticks are no good. But elsewhere there is the table (image attached), which confuses me... it seems to suggest you can use an 8mb stick, but how does one 8mb stick equal 32mb total? The ones I've bought were sold as "Kingston 72 Pin Memory SIMMs. 2x 8MB (16MB total) 60ns Fast Page" and I looked up the chip number on them (TC5118180AJ-60): "IC 1M X 18 FAST PAGE DRAM, 60 ns, PDSO42, Dynamic RAM"

evildave9000 wrote on 2020-03-13, 12:58:

Hi Horun - The manual I've found online says it supports parity and non-parity. I don't really understand memory configurations too well, and having read through the manual again, I'm not much clearer. It says:

"Mix 256K, 1M, and 4M SIMM (8 bit/32 bit) Module DRAM memory"

So that would mean my 8mb sticks are no good. But elsewhere there is the table (image attached), which confuses me... it seems to suggest you can use an 8mb stick, but how does one 8mb stick equal 32mb total? The ones I've bought were sold as "Kingston 72 Pin Memory SIMMs. 2x 8MB (16MB total) 60ns Fast Page" and I looked up the chip number on them (TC5118180AJ-60): "IC 1M X 18 FAST PAGE DRAM, 60 ns, PDSO42, Dynamic RAM"

I fully agree, that's confusing.
According to the table you posted 2 times 8MB should work.

https://stason.org/TULARC/pc/motherboards/P/P … 486-PT-430.html
But here it's not listed as an option, so only one time 8MB is mentioned.

So take out one of the 8MB sticks and check if it changes something.

EDIT: If I googled the right manual (I am not sure honestly spoken):

....
These are 32-bit modules (sometimes referred to as ‘x32’ or ‘x36’). Because they are fully 32-Bit you only need to use one piece as opposed to 4 pieces of 30-Pin module above. Therefore this type of SIMM occupies one bank on its own. The exception to this rule is that some 72-Pin modules are double sided and will occupy two banks. The table below shows you what types of SIMM are single or dual banked.
....

so that could indicate that only one module would work.
But maybe those modules you have bought do not work at all in this board.
It's possible that you can only use (my count of chips is only for the non parity case)
4MB modules (single sided with 8 chips), 2 are possible.
8MB module (double sided with 16 chips), only 1 is possible.
16MB modules (single sided with 8 chips), 2 are possible
32MB module (double sided with 16 chips), only one is possible.

You have 8MB modules double sided with 4 chips, maybe they don't work at all. I don't know

Ok, so I bought an 8Mb parity stick off eBay and it now turns on! Video BIOS does its thing. System BIOS loads and memory tests OK. It detects the compact flash card I have attached via an adaptor and old VESA I/O card. I get to the post BIOS check screen, the one with the table detailing the installed hardware. But no further. Last thing it says, under the table, is:

256k CACHE MEMORY
80Mhz CPU Clock
384k SHADOW RAM

Then it hangs. It doesn't seem to attempt to boot anything. Ctrl+Alt+Del doesn't work. I would take a picture of the screen, but I've put it all away for tonight. It does the same thing whether the I/O card is installed or not. The eBayer I bought it from showed the same screen in the listing, but he had got the error message attempting to access the floppy disk (he had no fixed or removable drives installed, as I can see from the same picture). So I'm thinking it is a setting in BIOS or the jumper configuration? He had a different CPU installed, so perhaps I have that set up wrong? But then, would it get as far as it does if the CPU is not set up correctly?

Just realised I can upload the picture from the eBay listing to illustrate what I mean. So mine doesn't get further than the line 384k SHADOW RAM.

evildave9000 wrote on 2020-03-31, 20:24:

Ok, so I bought an 8Mb parity stick off eBay and it now turns on! Video BIOS does its thing. System BIOS loads and memory tests […]
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Ok, so I bought an 8Mb parity stick off eBay and it now turns on! Video BIOS does its thing. System BIOS loads and memory tests OK. It detects the compact flash card I have attached via an adaptor and old VESA I/O card. I get to the post BIOS check screen, the one with the table detailing the installed hardware. But no further. Last thing it says, under the table, is:

256k CACHE MEMORY
80Mhz CPU Clock
384k SHADOW RAM

Then it hangs. It doesn't seem to attempt to boot anything. Ctrl+Alt+Del doesn't work. I would take a picture of the screen, but I've put it all away for tonight. It does the same thing whether the I/O card is installed or not. The eBayer I bought it from showed the same screen in the listing, but he had got the error message attempting to access the floppy disk (he had no fixed or removable drives installed, as I can see from the same picture). So I'm thinking it is a setting in BIOS or the jumper configuration? He had a different CPU installed, so perhaps I have that set up wrong? But then, would it get as far as it does if the CPU is not set up correctly?

Just realised I can upload the picture from the eBay listing to illustrate what I mean. So mine doesn't get further than the line 384k SHADOW RAM.

So you are using now 2 times 8 MB sticks, right?
Please check my previous posting, better use only 4MB sticks or 16MB sticks single sided with that board.

EDIT: If you are using only one 8MB stick, something is definitely wrong, because the BIOS reports 16MB 😁

EDIT2: OK, that was not an actual screenshot, ignore my last remark.
But I still wonder why you bought an 8MB stick, completely ignoring what I wrote.

I figured I would buy a parity chip and see if that worked as someone else mentioned parity vs non-parity. Also, as I had no idea which parts work, I wanted to at least get it to POST, which it now has. So I can say that the motherboard, the CPU, the 1x8Mb RAM stick, the graphics card and the I/O card all work, at least partially. Before I had no idea if any of it worked.

You said "8MB module (double sided with 16 chips), only 1 is possible." - this is now the set up I have, albeit the stick has 3 chips per side. I noticed that although the manual says it supports parity or non-parity, the data sheet on stason.org only mentions x36 memory for the 72-pin banks, so I figured I'd try a parity chip. I think the original ones I bought are too new. Maybe too fast a clock speed or something. They're probably out of a much later Pentium-based system.

evildave9000 wrote on 2020-04-01, 00:50:

I figured I would buy a parity chip and see if that worked as someone else mentioned parity vs non-parity. Also, as I had no idea which parts work, I wanted to at least get it to POST, which it now has. So I can say that the motherboard, the CPU, the 1x8Mb RAM stick, the graphics card and the I/O card all work, at least partially. Before I had no idea if any of it worked.

You said "8MB module (double sided with 16 chips), only 1 is possible." - this is now the set up I have, albeit the stick has 3 chips per side. I noticed that although the manual says it supports parity or non-parity, the data sheet on stason.org only mentions x36 memory for the 72-pin banks, so I figured I'd try a parity chip. I think the original ones I bought are too new. Maybe too fast a clock speed or something. They're probably out of a much later Pentium-based system.

Of course I can't be sure, but I think you have still the a problem with the RAM.
Are you able to enter the BIOS with the new 8MB stick?
If yes, did you already set everything back to BIOS default?

I can get into the BIOS. I've tried "standard", "optimal" and "fail-safe" settings, but it doesn't really do anything different. Only thing that changes is on fail-safe it doesn't show the 256k cache line, or the 80mhz CPU Clock. Still says 384k Shadow RAM and hangs at that point.

One thing I noticed is that in the table it shows the main processor as "Cx486DX2", but the one I'm using is an "It's ST 486 DX2-80". On the chip it says ST486DX2-80GS under the logo, so I would expect it to say something closer to that. I set up the jumper config for data write-back cache - described as P24D/Write-Back in the manual - as that's what it says it has on cpu-world.com. I'm thinking that I need to try a different CPU config.

I may buy some 30 pin memory as well to rule out a memory problem.

evildave9000 wrote on 2020-04-01, 15:24:

I can get into the BIOS. I've tried "standard", "optimal" and "fail-safe" settings, but it doesn't really do anything different. Only thing that changes is on fail-safe it doesn't show the 256k cache line, or the 80mhz CPU Clock. Still says 384k Shadow RAM and hangs at that point.

One thing I noticed is that in the table it shows the main processor as "Cx486DX2", but the one I'm using is an "It's ST 486 DX2-80". On the chip it says ST486DX2-80GS under the logo, so I would expect it to say something closer to that. I set up the jumper config for data write-back cache - described as P24D/Write-Back in the manual - as that's what it says it has on cpu-world.com. I'm thinking that I need to try a different CPU config.

I may buy some 30 pin memory as well to rule out a memory problem.

No, wait.
When you are able to go into the bios, the ram should not be faulty.
You wrote something like
" .... It detects the compact flash card I have attached via an adaptor and old VESA I/O card"
So to 99.99% that's the reason for the "hang".

I guess you can boot from a floppy disk or from a normal harddisk without any problem. Is that correct.

Re: Computer hangs at boot ?

Do you have the same problem?

Hmmm.... I will try this shortly, but I'm pretty sure it hangs at the same point even without the I/O card installed. I would expect it to say MISSING OPERATING SYSTEM or NO BOOT MEDIA or something to that effect. Unfortunately, I don't have a floppy drive to try it, though I may have an old hard disk somewhere that I could try. I'll get back to you...

Finally! I have it booting MS-DOS from the compact flash! After messing around with various configurations of the I/O card and the compact flash, I decided it wasn't that. Changed the CPU configuration to DX2 - it wouldn't even POST. On a whim, I tried the CPU configuration for P24T that is in the manual - don't know what P24T means, but... lo! and behold! It worked! Well, it was now displaying one more line: "MISSING OPERATING SYSTEM". So after pretty much a full day messing around with a virtual machine formatting and fdisking the compact flash in various ways, I finally got it to boot MS-DOS 6.22. Several more hours were spent getting the Sound Blaster to work (didn't help that I thought I'd bought an AWE32, but it turns out it is actually an AWE64). That's also working - had sound in Space Quest III and Wing Commander (which runs waaayyy too fast, so gonna need to put in a turbo switch if I want to play that).

So a problem I noticed when I first got it to POST and enter BIOS, is the screen looks pretty weird. There are vertical straight lines running down the screen, truncating the display. It messes up the text in DOS. I've attached some photos. It's going through a 10 - 15 year old flat screen, so it could just be the monitor. Could it be the VGA card doesn't display correctly on an LCD? Or is this something else that someone has come across? Something on the VGA circuit board faulty or failing?

It's not actually very clear in the photos, but IRL it is very noticeable, especially in text mode. If you zoom in, you can see some of the letters are cut off.

This is your LCD doing this. Need to try another LCD monitor.

Cheers,

Yup, plugged into my main monitor and it's fine.

Thanks for your help, everyone!

What is this monitor that look awful and one that works correct? We like to know.

Cheers,