IBM port 80 POST codes (Netfinity 3500 M10)? \ VOGONS

IBM port 80 POST codes (Netfinity 3500 M10)?

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First post, by dionb

Posted on 2021-02-04, 22:55

dionb Offline

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My muddy, rained-upon dual Sl1 i440LX board lives again!

Or at least, after that abuse, then getting dishwasher treatment here and two weeks to be completely dry, it's doing something. Just not everything....

Board is an IBM Netfinity 3500 planar, part number 93H7269

Board has one jumper (CMOS clear) and a set of 8 switches. Documentation for those can be found here:
http://ps-2.kev009.com/basil.holloway/ALL%20PDF/3500uhen.pdf

After messing around with RAM and VGA (no POST at all with non-parity RAM...), best I've found so far:
- P2-300 Klamath CPU (officially supported, with correct switch settings for it)
- Slot 1 terminator in CPU2 slot.
- 128MB PC100 ECC unbuffered SDRAM
- Hercules GeForce2MX AGP card (same results with S3 Virge PCI card, system completely refuses to boot with Matrox Millennium 2 PCI)
- FSP 350W 5V-heavy PSU with ATX-20 and AUX cables connected
- vintage ISA Port80 POST card

This clearly starts POST. After quickly flashing through a number of POST codes, it settles on 4C for a bit, then moves on to 7A and seems to hang. Screen stays blank.

Now, there are various resources for POST codes, but most only have much older IBM ones (AT and PS/2 MCA) such as here:
http://www.bioscentral.com/postcodes/ibmbios.htm

IBM has its own documentation, but the codes are screen codes that don't help if your screen doesn't show anything:
https://www.ibm.com/support/pages/post-error- … -netfinity-3500

So, anybody got an idea what this board is trying to tell me with "7A"?

Reply 1 of 3, by Horun

Posted on 2021-02-05, 03:41

Horun Offline

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I looked thru Bigelow's PC Tech Trouble shoot ref from 1999 and it had nothing good you did not already find. Looked thru my IBM NetVista docs but no real POST cards codes found that would help. Will look around tomorrow but have doubts will find anything.

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 2 of 3, by dionb

Posted on 2021-02-05, 15:01

dionb Offline

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Horun wrote on 2021-02-05, 03:41:

I looked thru Bigelow's PC Tech Trouble shoot ref from 1999 and it had nothing good you did not already find. Looked thru my IBM NetVista docs but no real POST cards codes found that would help. Will look around tomorrow but have doubts will find anything.

Thanks.

Given market segment this board might just be configured to send stuff over serial port. Will dig up my USB-to-serial adapter and see if it is...

Reply 3 of 3, by mr.cat

Posted on 2021-02-07, 00:33

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Just for laughs I tried running the BIOS image $IMAGEPK.USF in bochs. I got that image from 19k8363.img (it can be extracted with 7z), hopefully that's the right one?

I found this code at 0xfe150, so that's where I put the breakpoint:

100000000000fe150: (                    ): out 0x80, al              ; e680
200000000000fe152: (                    ): mov dx, 0x0378            ; ba7803
300000000000fe155: (                    ): out dx, al                ; ee
4..

Well it doesn't get very far, the last code it outputs to 0x80 is 0x0e.
That 0x378 is the parallel port, so the same code can be read there too.
Bochs doesn't have support for i440LX btw, so I used i440BX, the next one in line.

EDIT: It looks there is a table which has all the POST codes and an offset to jump address. For example, POST code FA has offset 03fa, which corresponds to address 0xfc3fa.
Looking at the code there, it pokes value 0x80000058 to port 0xcf8 and then reads port 0xcfc - PCI configuration space?
The POST codes appear in this order: 4C, 7A, FA. I made the assumption that the POST code is poked to 80h first, and the routine is then executed.

The problem is, I'm very clueless when it comes to this kind of thing. Maybe someone with better BIOS/assembly understanding can make some sense of it.
Some of that PCI configuration space related stuff can be found in the chipset documentation.

EDIT3: Peeking at that code at 0xfe4fa (POST code 7A), it looks like it's trying to do some disk operations via INT 13h.

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