BIOS Updates forum

Trying to recover a 6ZX81 board with this BIOS chip:

#F29C51002T = Mosel V29C51002T | 256KB

Unsure of which two address pins to short to force bootblock but I ejected another board's BIOS chip and replaced it with the above once the command prompt was idling.

I flashed the latest BIOS to the chip but it came up with a data verification error once completed - consistent every time even when I tried different voltages on the BIOS chip. According to UniFlash documentation UniFlash has been tested with this chip but does not work with it the way it should, so I am wondering whether this is where I am running into problems or not.


The owner of this board has some spare boards around which have different problems and faults with them - some still run. I want to see if one of these boards has a 256KB flash chip that should work OK with UniFlash; flash the Acorp 6ZX81 BIOS onto it, and then install the chip into the board (Acorp) in question (because I'm not sure whether the actual board is faulty or if the BIOS is just corrupt.

Questions:

What other issues do I need to be careful of with the above plan. Such as, will UniFlash flash the image using a different board without troubles, providing UniFlash is compatible with the chip? What about BIOS voltages once I transfer the chip to the Acorp board? Any other issues?

I could use the original chip from the Acorp board in another hotflash, but I'm not sure about the comptability between UniFlash and that chip as well as the fact that the pins are a bit bent from being removed and re-inserted several times.

If you see a Data Verification Error msg after the flashing process, the BIOS chip is defective.

I've encountered this same problem with some of my BIOS chips that were really defective. But replacing with a known good chip having the same capacity/pin-out/supply voltage fixed the problem.

Hi rulenov

I'm still wondering whether it could be that UniFlash's documentation has an # marked next to this chip.

However, assuming you are correct, probably a surge killed the BIOS chip. Hopefully this is the only hardware that suffered damage - because then I may be able to recover the board by putting a good chip with the correct BIOS in.

As long as you don't see this msg "Unknown Flash" and you are able to flash that chip but got the Data Verification Error msg, I'm quite sure it's a defective BIOS chip.

Either way, I am hoping to retrieve a BIOS chip from a dead board and replace that chip with one that is not defective, and hopefully which is known to work well with UniFlash.

And after what I've seen with Award Flash, I don't trust it enough to do the job.

I have now observed that both a 1Mb and 2Mb BIOS image are available for this board.

I only have 1Mb spare BIOS modules around at present.

The board had a 2Mb module.

So if I flash a 1Mb image onto a 1Mb module, can I use it in the Acorp board? Do I need to change any jumper settings or do anything else to allow this to work?

Or is this not possible without a specific version of this board designed for the 1Mb module.

Thanks in advance.


Ritchie

It's not a problem flashing a 1MBit Flash ROM on a board that originally had a 2MBit chip.

No other changes to make.

But if I used a different chip to what was originally in the board, would there, for example, be possible voltage changes to make?

For example, the PC Partner VIB878DS board has a BIOS select jumper, to select different voltages and different BIOS sizes.

I could not find anything on the Acorp board or manual - does this mean that it is automatic on the Acorp board?

Your Acorp board can accept lower or higher capacity flash ROM, but the chip has to have the same voltage supply rating as the original flash ROM. I mean, if you hotflash a 3.3V flash ROM it would be burned if the voltage supply for the original flash ROM is 5V.

This being the case since your Acorp board doesn't have voltage setting jumpers.

You don't think it might auto-detect the flash module voltage?

I don't think so.

AFAIK, the majority of boards are designed with a fixed flash module voltage (can either be 5V or 3.3V/12V p-p), unless the board has jumpers to set this voltage.

How can I tell what voltage the boards and modules are?

The voltage supplied to the flash ROM is indicated in the datasheet of the original flash ROM for that board, or you can take a direct voltage readout using a DC voltmeter from GROUND to PIN 32 of the installed flash ROM.