Heath/Zenith 150-303 EGA Card

[ab0tj]

Hi all. I ended up with one of these cards but the system doesn't boot with it installed. I'm not seeing anything physically wrong with it but the BIOS EPROM is missing the cover over the window, so I'm wondering if it might have been partially erased over the years. Does anyone happen to have one of these cards that they could make an image of the ROM that I could try in mine? Or maybe even from another card with the CHIPS P82C434/431 chipset on it?

 

[modem7]

If you remove the EPROM, do you then observe activity (e.g. end-of-POST beep, activity LED on A: turning on momentarily) ?

 

[ab0tj]

If you remove the EPROM, do you then observe activity (e.g. end-of-POST beep, activity LED on A: turning on momentarily) ?

Actually, yes. I get one long beep and two short. Then all the other normal boot sounds (floppy seek, etc). This is on a IBM 5170 with Quadtel BIOS, by the way.

 

[modem7]

Heath/Zenith 150-303 EGA Card

I see one pictured at [here].

If you remove the EPROM, do you then observe activity (e.g. end-of-POST beep, activity LED on A: turning on momentarily) ?

Actually, yes. I get one long beep and two short. Then all the other normal boot sounds (floppy seek, etc).

So with the EPROM inserted, any beeps at all ?

Or maybe even from another card with the CHIPS P82C434/431 chipset on it?

At [here] are some ROM images. I see from the photo of the AST-3G there, that the AST-3G uses the P82C434/P82C431 chipset.

 

[ab0tj]

I see one pictured at [here].

I think that might be the same card I got :D But cheaper making an offer on eBay.

So with the EPROM inserted, any beeps at all ?

None at all. No other signs of life either. I have a POST code checker but I'm not sure if it has ISA or just PCI so I'll dig that out tonight to see if anything happens.

At [here] are some ROM images. I see from the photo of the AST-3G there, that the AST-3G uses the P82C434/P82C431 chipset.

Thanks, I'll give it a shot.

 

[ab0tj]

Perhaps its not the ROM after all. A dump of the ROM has a checksum of 00, as expected. Maybe I just got a dead board?

 

[modem7]

Perhaps its not the ROM after all. A dump of the ROM has a checksum of 00, as expected. Maybe I just got a dead board?

Following are two situations in which I see a corrupt BIOS expansion ROM 'hanging' the host computer.

Reference diagram at [here].

Possibility #1

The ROM size byte set by the programmer correctly reflects the size of the ROM, or reflects the code size in the ROM. Some bytes in the code have changed, but changed in a way that the 8-bit checksum of the declared ROM/code size remains at 00. I expect that to be rare. The POST passes execution to the corrupted code, then at some point, the code hangs the computer.

Possibility #2

The BIOS programmer set the ROM size byte incorrectly, incorrect in that it reflects part of the code size, not all of it. For example, if I examine the BIOS expansion ROM in my Seagate ST21M, the ROM size byte indicates 14KB, but I see that the code goes past 14KB. So, imagine the corruption being in the portion after 14 KB. The POST will find the 8-bit checksum of the first 14KB to be 00, pass execution to the corrupted code, at at some point, the code hangs the computer.

 

[ab0tj]

Thanks. I checked my dump of the ROM and it has the 3rd byte set to 20h which seems to be correct for a 27128 ROM. So I think it's at least not the second possibility. I'll try the AST BIOS image later today anyway just in case it is option #1.