Author Topic: CPC Mainboard Versions  (Read 33341 times)

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Offline nocash

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Hi, I've tried to compile a list of all CPC mainboards here, http://cpcwiki.eu/index.php/Mainboard_Versions. There seem to be many-many of versions & sub-versions.

Some pictures are still missing (marked by the red circle with invisible white question mark), and probably further boards exists, which aren't listed at all. I hope some people will add more board numbers & photos!

Oh, and maybe one or two listed versions didn't exist at all (for example, the "CPC6128 version 1.5", does that exist?) (and maybe the drawings in the service manuals were unreleased prototypes?).
« Last Edit: 03:27, 10 April 10 by nocash »

Offline robcfg

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Re: CPC Mainboard Versions
« Reply #1 on: 18:28, 09 April 10 »
I've been trying to spot differences between the picture of my 664 board and the one in amstrad.cpc.free.fr and they're almost identical but for a couple of details.


As you say it reads MC0005B instead of MC0005A and you can find a resistor attached a bit up from a small IC near the A of Amstrad.

Offline nocash

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Re: CPC Mainboard Versions
« Reply #2 on: 03:25, 10 April 10 »
Found another pic of the MC0005B while moving pics from the cpcwiki coppermine gallery. It's better resolution than the free.fr one, and has the extra resistor, too. Btw. good finding! I didn't notice that there was an extra resistor.

Hmmmm, only two 664 boards... is that all? Was the 664 discontinued when the 6128 came out? Or should there be also newer 664 boards existing?

Or, possibly 664s with newer 6128 boards inside (without PAL and with only 64K RAM installed), the 6128 board does have that option, but no idea if it that variant was ever produced?

Offline nocash

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Re: CPC Mainboard Versions
« Reply #3 on: 03:36, 10 April 10 »
Does somebody know why there were GX4000 boards without TV modulator?
Maybe Amstrad supported only PAL modulators, but no SECAM ones... so french versions never included modulators?
Or were there special super GX4000 versions with monitor instead modulator?

Offline arnoldemu

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Re: CPC Mainboard Versions
« Reply #4 on: 11:03, 10 April 10 »
Does somebody know why there were GX4000 boards without TV modulator?
Maybe Amstrad supported only PAL modulators, but no SECAM ones... so french versions never included modulators?
Or were there special super GX4000 versions with monitor instead modulator?
I am sure this is documented? Maybe it's in the GX4000 user manual? The French version doesn't have modulator. The English version has modulator.
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Offline gerald

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Re: CPC Mainboard Versions
« Reply #5 on: 12:37, 10 April 10 »
Does somebody know why there were GX4000 boards without TV modulator?
Maybe Amstrad supported only PAL modulators, but no SECAM ones... so french versions never included modulators?
Or were there special super GX4000 versions with monitor instead modulator?

SCART was mandatory for coulor TV sold in France since 1980. I do not know if it was the case in other country.
So Amstrad saved on the PAL encoder and modulator, assuming that french user should have a proper TV set.

Offline robcfg

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Re: CPC Mainboard Versions
« Reply #6 on: 13:57, 10 April 10 »
Quote
Btw. good finding! I didn't notice that there was an extra resistor.

Thanks man. It took me some minutes just looking at the two pictures just to notice it. Otherwise they seem identical.

What do you think it is the purpose of the resistor? You can see also the bottom side of the MC0005A board here.

By the way, this is a very interesting thread, I'll have to check my 6128's for any of the missing pcb revisions.

Offline robcfg

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Re: CPC Mainboard Versions
« Reply #7 on: 15:51, 10 April 10 »
I just scanned the 6128 rev 2 (Z70290 MC0020B) board at 300dpi resolution.

You can find it in the gallery, in the CPC Old Generation article or in the Mainboard revisions article.

Offline nocash

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Re: CPC Mainboard Versions
« Reply #8 on: 16:00, 10 April 10 »
Added a description of the resistor on the http://cpcwiki.eu/index.php/Mainboard_Versions page, not sure WHY it connects to those signals. Seems to have something to do with DRAM timings. Maybe they switched to another DRAM manufacturer, and then needed to add that patch.

For the GX4000. The User Manual doesn't really describe it. But if you look at the section with french language: The "parts list" drawing shows a scart cable instead RF cable. Though the french connection example still shows the RF cable.
The Service Manual contains separate RGB/Power schematics for french version, uploaded/extracted that schematic here, http://cpcwiki.eu/index.php/File:Edited_GX4000_French_Schematic.gif

Seems to be no-SECAM-support related. Atari didn't support SECAM too well, too (in their Atari 2600). Maybe, in turn, the french TV market had more TVs that support for RGB than other countries? In germany, Scart became standard between 1980..1990. But, I think most german "scart" TVs only had (and maybe still have) support for Composite (pin19), not for RGB (pin7,11,15). Been wondering about that anyways: How many old/now TVs have RGB support?

Offline nocash

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Re: CPC Mainboard Versions
« Reply #9 on: 16:11, 10 April 10 »
> I just scanned the 6128 rev 2 (Z70290 MC0020B) board at 300dpi resolution.
Perfect. Scans are looking even better than photos. I've removed the old photo from the Mainboard Versions page, so there's only one picture per board-version.
Maybe each board-version in the list should also have a link, to a page titled "More pictures of MC0020B" or so?
That way one could add different pics, close-ups, solder-side, etc.

 

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