Flash BIOS for 5170

hello,
I built a couple of small PCBs that can be plugged into the 5170 BIOS sockets (and presumably other motherboards of the era).

The PCBs have 0.1" pin rows spaced to match a 0.6" 28-DIP IC on one side, and a surface mount AT28C256's and a set of dip switches on the other. The switches configure the pins to match the configuration of the DIP package AT28C256 or the motherboard BIOS socket. The pins on the PCB are very small diameter machined pins that can be inserted in the motherboard socket without appearing to stress the socket at all - the pin diameter is smaller than the thickness of a DIP IC pin.

I programmed a couple of them in an old flash programmer with the AMI BIOS from minuszerodegrees.net and had no trouble booting my 5170.

If there's any interest I can post the gerber files somewhere. I might make a second pass at them using through hole pin headers instead of surface mount headers, as it would make alignment during assembly simpler, and narrowing the PCB slightly to avoid overlapping the empty extension sockets on the 5170. Probably stuck with SMT for the flash IC as through hole wouldn't fit between the pin rows and might interfere with insertion.

Picture of installed BIOS boards:

Hi,

Just wondering aloud why not use EPROMs (say 27C256) for this purpose? Not saying what you have done isn't cool, just wondering why you went that route?

Or even 28C256 EEPROMs...

Now, if it were possible to reprogram them in-place, perhaps to test quickly software with different bios revisions, that would be cool. At least until you get stuck in an unbootable state

SomeGuy said:

Now, if it were possible to reprogram them in-place, perhaps to test quickly software with different bios revisions, that would be cool. At least until you get stuck in an unbootable state

Click to expand...

Well, when I read the title at first I thought that is what he had accomplished - i.e. he had come up w/ a way to make the 5170 BIOS flashable... :D

Shadow Lord said:

Well, when I read the title at first I thought that is what he had accomplished - i.e. he had come up w/ a way to make the 5170 BIOS flashable... :D

Click to expand...

That is my end goal, if I can get there.. this is more of a proof of concept step to see if I can enough circuitry into a DIP package footprint to make it possible. For in system programming it looks like I need the /xmemw signal which isn't present in the BIOS socket and I haven't found a convenient place to tap into yet - if anyone has a suggesstion please let me know! If I'd used a 27C256 I would have had to provide it with Vpp as well, which would have meant additional connections to elsewhere in the system as well as additional controls to apply it.