+2A ROMs 0 - 3 on 2x Eprom

A place to discuss the ZX80's and ZX81's younger brother - the Sinclair ZX Spectrum
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Erm
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Joined: Thu Jun 20, 2019 7:07 pm

+2A ROMs 0 - 3 on 2x Eprom

Post by Erm »

Just to verify before I burn the ROMs.... the Spectrum +2A/+2B/+3 physically have 2x 32k ROM chips, usually referred to as A and B. I know that they consist of 4 banks of 16k ROM data.

Am I right in thinking that ROM A contains 16k ROMs 0 and 1 (with 0 starting at the beginning and 1 in the 2nd half) and that for ROM B it's the same principle, with the first 16k space taken up by ROM 2 and the last 16k being ROM 3?

Thanks.
I'm Chris, a Brit in Germany (Chr$ on the QL forum).
Lardo Boffin
Posts: 1270
Joined: Sat Nov 26, 2016 2:42 am

Re: +2A ROMs 0 - 3 on 2x Eprom

Post by Lardo Boffin »

Here is the inside of a +2A currently awaiting attention. Looks like two ROMs.

F16CEA5A-7DC3-454A-A655-BF163FEB5E22.jpeg
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
Iss 3 ZXVid
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Spectrum +2a
Lardo Boffin
Posts: 1270
Joined: Sat Nov 26, 2016 2:42 am

Re: +2A ROMs 0 - 3 on 2x Eprom

Post by Lardo Boffin »

Up close if required:

D93BEE89-9AEB-415D-86B2-864BB7C42EA8.jpeg
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
Iss 3 ZXVid
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Spectrum +2a
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Erm
Posts: 173
Joined: Thu Jun 20, 2019 7:07 pm

Re: +2A ROMs 0 - 3 on 2x Eprom

Post by Erm »

Yes, thanks Lardo, I know that there are two but they come as 4x 16k, so just wanting to confirm the correct order that they get burnt onto the chips.
I'm Chris, a Brit in Germany (Chr$ on the QL forum).
Lardo Boffin
Posts: 1270
Joined: Sat Nov 26, 2016 2:42 am

Re: +2A ROMs 0 - 3 on 2x Eprom

Post by Lardo Boffin »

ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
Iss 3 ZXVid
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Spectrum +2a
User avatar
Erm
Posts: 173
Joined: Thu Jun 20, 2019 7:07 pm

Re: +2A ROMs 0 - 3 on 2x Eprom

Post by Erm »

Just to make sure, I'm going to compare the ROM code of my original A&B to verify the 0-3 order.
I'm Chris, a Brit in Germany (Chr$ on the QL forum).
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