VOGONS


First post, by behshad

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Happy New Year everyone!

Just before Christmas, I bought an AT-style Socket 7 motherboard computer and have been trying to diagnose and get it working. It wasn’t functional when I got it. The case had some rust, but the most concerning issue was the condition of the CPU pins—many were rusted and fell out when I tried to remove the CPU (photo: https://ibb.co/vP4BwJ3). The CPU was a 120MHz Pentium. I have replaced it with a tested and working 133MHz Pentium.

Now, the motherboard (MSI MS-5124 https://theretroweb.com/motherboards/s/msi-ms-5124-si7#docs) powers on and posts, but I’m stuck at PC Analyzer code 410d. Additionally, I hear continuous beeps that I cannot understand (video: https://www.youtube.com/watch?v=mLEab8Lyurk). I’ve tried booting with different RAM sticks without success. The CPU voltage is correctly set to 3.38V.

Motherboard Photos: https://ibb.co/QFYJzgM & https://ibb.co/S5Ky8zF

According to the PC Analyzer booklet:

- Code OD refers to detecting the CPU clock, reading CMOS location 14h to identify the type of video in use, and detecting and initializing the video adapter.
- Code 41 relates to initializing the floppy disk drive controller and any connected drives.

Nothing is displayed on the screen. While the CPU had visible rust, the motherboard itself shows no obvious signs of corrosion as far as I can see.

Does anyone know what these continuous beeps might indicate or have suggestions for further diagnosis? Any help would be greatly appreciated!

Reply 1 of 9, by behshad

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By the way, I forgot to mention that I’ve also set the motherboard’s CPU speed jumpers to match the 133MHz processor (https://theretroweb.com/motherboard/manual/33222.pdf). Is there anything else that needs to be adjusted or changed on the motherboard when swapping the CPU?

Reply 2 of 9, by Chkcpu

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Hi behshad,

The hang at POST code 41 preceded by code 0D on the Award v4.50PG/v4.51PG BIOS means: BIOS Checksum Error.
So you have a corrupted or incorrect BIOS on your board! 🙁

This code sequence comes from the BIOS Bootblock and code 41 indicates that the BIOS attempts a recovery by checking for a bootable floppy with the Awdflash program and the BIOS BIN-file on it.

Do you have an (E)EPROM programmer to read and restore the BIOS in the flashchip?
If you post the BIOS dump here, I can tell you what’s wrong with it.
And if you install an ISA videocard, you should see the BIOS Error messages on the screen.

Greetings, Jan

CPU Identification utility
The Unofficial K6-2+ / K6-III+ page

Reply 4 of 9, by HalfmoonStudio

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Hi Beshad and all.
Been hanging around here for a wile, I love the socket 7 stuff also. was looking at your post.
perhaps it just a bad pic but it looks like your board might have some damage between the agp slots, looks like it got hit, the plastic on top looks like it moved around and the buffer under it looks beat up.

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Reply 5 of 9, by behshad

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Thanks, Jan! You seem to be right—using an ISA graphics card allowed me to boot, albeit very intermittently. I had to move the ISA card between different slots until one of them displayed on screen (https://ibb.co/BzTG2PB). However, it only works once; when I turn the motherboard off and back on, there’s no video output again, and the analyzer shows the code 0D0C with no beeps. I keep shifting the video card between ISA slots, and eventually, one might works again, but the issue recurs after every reboot.

Do you still think this could be due to a corrupted BIOS? I’ve been considering buying an (E)EPROM programmer from AliExpress for a while, and now seems like the right time. Are there any specific models or specifications I should look for?

Chkcpu wrote on 2025-01-05, 16:12:
Hi behshad, […]
Show full quote

Hi behshad,

The hang at POST code 41 preceded by code 0D on the Award v4.50PG/v4.51PG BIOS means: BIOS Checksum Error.
So you have a corrupted or incorrect BIOS on your board! 🙁

This code sequence comes from the BIOS Bootblock and code 41 indicates that the BIOS attempts a recovery by checking for a bootable floppy with the Awdflash program and the BIOS BIN-file on it.

Do you have an (E)EPROM programmer to read and restore the BIOS in the flashchip?
If you post the BIOS dump here, I can tell you what’s wrong with it.
And if you install an ISA videocard, you should see the BIOS Error messages on the screen.

Greetings, Jan

Reply 6 of 9, by behshad

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Hi HalfmoonStudio,

Great catch! 😀 What you’re seeing are remains of hot glue. For some reason, this motherboard had a lot of hot glue on the PCI slots. I used isopropyl alcohol to clean off as much as I could, but some residue remains. I plan to clean it up completely once the motherboard is up and running.

HalfmoonStudio wrote on 2025-01-05, 17:11:

Hi Beshad and all.
Been hanging around here for a wile, I love the socket 7 stuff also. was looking at your post.
perhaps it just a bad pic but it looks like your board might have some damage between the agp slots, looks like it got hit, the plastic on top looks like it moved around and the buffer under it looks beat up.

Reply 7 of 9, by Repo Man11

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"While the CPU had visible rust" - what steps have you taken to clean the CPU socket? Resistance caused by rust would be a possible explanation for the strange behavior.

"We do these things not because they are easy, but because we thought they would be easy."

Reply 8 of 9, by behshad

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Hi, I thought about this too, so I removed the plastic cover from the CPU socket and inspected it. Surprisingly, despite the terrible condition of the CPU pins, there was no rust on the pin holders inside the socket. Even so, I used some IPA and a toothbrush to clean the pin holders before replacing the socket cover.

Repo Man11 wrote on 2025-01-05, 23:28:

"While the CPU had visible rust" - what steps have you taken to clean the CPU socket? Resistance caused by rust would be a possible explanation for the strange behavior.

Reply 9 of 9, by Chkcpu

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behshad wrote on 2025-01-05, 22:50:

Thanks, Jan! You seem to be right—using an ISA graphics card allowed me to boot, albeit very intermittently. I had to move the ISA card between different slots until one of them displayed on screen (https://ibb.co/BzTG2PB). However, it only works once; when I turn the motherboard off and back on, there’s no video output again, and the analyzer shows the code 0D0C with no beeps. I keep shifting the video card between ISA slots, and eventually, one might works again, but the issue recurs after every reboot.

Do you still think this could be due to a corrupted BIOS? I’ve been considering buying an (E)EPROM programmer from AliExpress for a while, and now seems like the right time. Are there any specific models or specifications I should look for?

Chkcpu wrote on 2025-01-05, 16:12:
Hi behshad, […]
Show full quote

Hi behshad,

The hang at POST code 41 preceded by code 0D on the Award v4.50PG/v4.51PG BIOS means: BIOS Checksum Error.
So you have a corrupted or incorrect BIOS on your board! 🙁

This code sequence comes from the BIOS Bootblock and code 41 indicates that the BIOS attempts a recovery by checking for a bootable floppy with the Awdflash program and the BIOS BIN-file on it.

Do you have an (E)EPROM programmer to read and restore the BIOS in the flashchip?
If you post the BIOS dump here, I can tell you what’s wrong with it.
And if you install an ISA videocard, you should see the BIOS Error messages on the screen.

Greetings, Jan

Hi behshad,

Okay, you got the board to POST correctly once, and your picture shows the correct POST code 4E for the “Press F1 to continue, DEL to enter SETUP” state.
This means the BIOS is fine and the earlier “BIOS Checksum Error” codes and intermittent hang at POST 0D are caused by something else.

Because these Award v4.5xPG BIOSes are compressed and need RAM to decompress its modules, a BIOS Checksum error can also be caused by flaky RAM and a closer look at the memory system is needed. Look for corroded SIMM slot contacts or solder joints, trace damage, or loose pad contacts of the chipset legs.

The reason I advised the ISA videocard is because the BIOS Bootblock code has only ISA bus support. So in case of an actual BIOS corruption, you need the ISA card to see what’s going on.
But now the BIOS appears to be healthy, you can use a PCI videocard as well.

I agree that an (E)EPROM programmer is an essential tool when tinkering with retro PCs. I have such a device but if I needed a new one, I would go for the Xgecu T48.

Cheers, Jan

CPU Identification utility
The Unofficial K6-2+ / K6-III+ page