VOGONS


First post, by Jackal1983

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My Headland HT-12A based 286 board has 2 American Megatrends branded bios chips in the standard Odd/Even configuration. I'd like to back them up using my TL866 but none of the numbers look like prom numbers:
1st Line is a date code and AMI
2nd Line: 286E-0 A
3rd Line: #C18864
4th Line: 764-117250-020D

Any ideas of how to read these chips safely and what modern eproms (or eeproms) might be compatible?

Reply 1 of 7, by weedeewee

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the info you are looking for should be underneath the stickers.

generally, it's a 27C256 or compatible I think.

Right to repair is fundamental. You own it, you're allowed to fix it.
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Reply 2 of 7, by Jackal1983

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weedeewee wrote on 2022-05-19, 07:57:

the info you are looking for should be underneath the stickers.

generally, it's a 27C256 or compatible I think.

There is no sticker, that's what is printed directly on the ceramic package

Reply 3 of 7, by weedeewee

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Well, reading them like they are a 27c256 should work.

Right to repair is fundamental. You own it, you're allowed to fix it.
How To Ask Questions The Smart Way
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Reply 4 of 7, by Jackal1983

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weedeewee wrote on 2022-05-19, 08:46:

Well, reading them like they are a 27c256 should work.

Alright, thanks: I read it as a Am 27c256 and it worked after throwing a bad pin error on pin 1 (Vpp) which makes sense considering this is either a mask rom or a old school (fused) OTP ROM. I'd like to try the MR BIOS version for the HT-12, any suggestions for splitting it into odd and even rom images so I can burn it onto a set of 27c256s?

Reply 5 of 7, by weedeewee

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I've used this, https://github.com/freem/romwak , program myself a few times.
binary can be found under releases https://github.com/freem/romwak/releases/tag/0.3c

I didn't know there was an Mr Bios for the ht-12. Interesting since I've got several boards with that chipset.
I am a bit disappointed that it only does 4MB of RAM.

Right to repair is fundamental. You own it, you're allowed to fix it.
How To Ask Questions The Smart Way
Do not ask Why !

Reply 6 of 7, by Jackal1983

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weedeewee wrote on 2022-05-19, 19:40:
I've used this, https://github.com/freem/romwak , program myself a few times. binary can be found under releases https://github. […]
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I've used this, https://github.com/freem/romwak , program myself a few times.
binary can be found under releases https://github.com/freem/romwak/releases/tag/0.3c

I didn't know there was an Mr Bios for the ht-12. Interesting since I've got several boards with that chipset.
I am a bit disappointed that it only does 4MB of RAM.

I could be wrong, but I remember seeing an entry for the HT-12 in the Mr Bios archive thread

Reply 7 of 7, by Jackal1983

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Ah, it's these files:

-------------------------------------------------------
Headland Technologies HT12/12+, HT22/18C, HT320, HT340
-------------------------------------------------------

Filename Port Description - HT12/HT12+
-------- ------- ---------------------------------------------------------
V039B200 HT12200 286 HT12/HT12+
V039B201 HT12201 x039b200 (T-)
V039B202 HT12202 x039b200 (T+)

V039B210 HT12210 286 HT12/HT12+, built-in EMS
V039B211 HT12211 x039b210 (T-)
V039B212 HT12212 x039b210 (T+)

Re: How about a MR-BIOS ROM file repository?

Download MRBIOS_3.zip, the relevant files are in the Mr Bios 6 folder inside the zip file.