512K RAM Expansion - Schematics?

[Nilquader]

I'm trying to build a cheap (and small) 512K RAM expansion for the CPC. Maybe something like this RAM BOX - CPCWiki - Does anybody have the schematics for such a device? I know that there are schematics for the Inicron RAM-BOX available but that one isn't fully compatible.

[MacDeath]

such card will soon be available... probably for a reasonnable price...


Well you may have to also get a Mother x4 as well...




Cent Pour Cent - CPC News




the shop is closed at the moment.
I guess it is a bit of a shame because we can't see the cards in existence...


TotO should let some pages, just disable the "buy" option for the moment.

[TotO]

No, I can't simply disable the buy option and I can't sell anything before January.
You can see the existing boards from the main page.

Yes, a RAM expansion will be available for an affordable price in some weeks.

[Nilquader]

I wanted to have something very small, so I looked for something like the RAM-BOX (see above). The Motherx4 + RAM-Expansion will be too big to be put into a small case.

[TotO]

The MX4 expansion boards are 8x5cm formated. (half of a 3" floppy)

[MacDeath]

Perhaps, you can only plug one card without the Mx4, just need the proper cable I guess?

I was misguided by those 3 thread about the 512K card and failed to see all other cards have their page.

[Nilquader]

I've been looking for schematics, Not a finished product. Maybe it's possible to put the complete logic into a small CPLD and build an even smaller RAM expansion...

[TotO]

There is no schematic on Internet actualy.
If you want to build your own expansion using a CPLD, then you got all the technical informations on Internet to start your project from cpcwiki and grimware.

Good luck.

[Bryce]

As far as I know Yarek released all his schematics (including the RAM expansion you posted) here: CPC4MB RAM upgrade -- 8bit Projects For Everyone
I've never tried it (you need to create an account and log in), but supposedly everything you need should be there.

Bryce.

[TotO]

The links are dead as I know.
I have sent a message 1 year ago w/o answer.

[Bryce]

Oh, I didn't know that. As I said, I've never tried.

Bryce.

[TFM]

Well, then check out http://www.inicron.de


Of course you need Eagle.

[Bryce]

Well, then check out http://www.inicron.de


Of course you need Eagle.

In fact you'll need a commercial version of eagle. You'll also need to hand edit the files to make them Eagle 6.x compatible if you are using a recent version.

Bryce.

[TotO]

Oh, I didn't know that. As I said, I've never tried.

Yes, only few links are working on this dead website, and because everybody make links and not backup the content look to be definitively lost, since.
As I know, those expansions only support C0, C4-C7.

[beaker]

I've got one (Yareks 512k) that Bryce did some work on a year or so back that I want to use with the CPC 464 (hopefully will keep MacDeath happy  ).

If there's anything I can do to help let me know.

[TFM]

Yes, only few links are working on this dead website, and because everybody make links and not backup the content look to be definitively lost, since.
As I know, those expansions only support C0, C4-C7.

Jareks 4 MB RAM expansion also support C3. I never had a problem with it.

[TotO]

I answered about the RAM-BOX, for the second part of my post.

[Nilquader]

Well, if you could make some high quality photos so that you can see the traces on the board (at least the ones that are not hidden by chips) and read the chip types, that would help.

Yareks 512k expansion only supports C0, C4-c7? Maybe it's really better to use a CPLD and support everything.

[TFM]

Some of that should be somewhere in the wiki

[beaker]

Well, if you could make some high quality photos so that you can see the traces on the board (at least the ones that are not hidden by chips) and read the chip types, that would help.

Yareks 512k expansion only supports C0, C4-c7? Maybe it's really better to use a CPLD and support everything.

Are these OK?

[Bryce]

I just checked back through my mod documents (I document every job with fotos). Here are some hi-res pics I took of Yareks 512K expansion with the connector removed, where more of the connections are visible:

Bryce.

[TotO]

Difficult to read the IC parts numbers.
I may be wrong, but a fast look on the pictures suggest that this board not support C3 on 464/664.
It's not really a problem, as C3 is used on few 6128 programs only and it may damage the Z80 if handled like the DK'Tronic does.

[beaker]

You could be right, my CPC464 is in no state to test it at the moment and it does state 6128 on the board.

I guess I'll be buying one of your boards as well when it's ready 

[TotO]

My expansion only support 50% C3 actually. I use a CPLD to fit on a MX4 expansion board, w/o SMD parts.
I have done more tests to fully support C3 on it, for 464/664 users. It's not easy, but gerald look to achieve that.

He explain me how, but I don't get good result actually as I have not his hardware for making tests.
It's why I have not released the board for Christmas (6128 only)... I don't what that you need a CPLD update later.

[TFM]

6128 is the future. 464 and 664 never cared about 6128, so now forget about them. Focus on 6128 and C3 shouldn't be a problem there.    No offense against 464/664 users, but you can't expect everything to be downgraded for you. No offense in general - that's just my opinion and you are entitled to have your own. 


EDIT: A quick check to verify &C3 working is to start symbos or FutureOS. In the latter case the mouse arrow leaves traces on screen if &C3 is not properly supported.