64K Memory Expansion

[magnut]

Hi All

Just joined here. I have a nice collection of Amstrad CPC's, 3 464's, 3 664's and 4 6128's, 2 CTM 644's and two LCD monitors rigged up to work with the CPC's. Plus I have a few spare 6128's for parts etc... Okay, credentials done, now on to my question...

I'm interested to find out if anyone ever worked out a schematic for doing an internal 64K memory upgrade on a 464 or 664? I've seen plenty of discussions around the traps, but never a resolution.  Memory expansion cartridges are so hard to come by these days I figured the best way would be to make one.  I've seen a few memory expansions that I can get online for 4Mb etc, but I'm happy with the 128K. I also have a collection of RAM chips out of a 6128 I could make use of.

On a side note, has anyone ever noticed that the 664 runs ever so slightly slower than a 464 or 6128?

Cheers

Danny

[simondo]

http://8bit.yarek.pl/upgrade/cpc.flash/index-de.html but I think it is 6128 only and probably the one you refer to.


http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/2-mega-byte-memory-expansion/


Second hand X-MEM?


I know Zaxon (Piotr Bugaj) has been seen making DK'Tronics clones and a similar mod to yarek as seen on Facebook but I don't think he sells them.

[Sykobee (Briggsy)]

I think the problem internally is getting somewhere to connect the expansion to. You can't just piggyback the RAM chips with a bent-pin+wire for the high-end address bits either.


Also all the different revisions of the 464 motherboard make it difficult to scale a solution up.

[magnut]

Thanks for the replies... Okay, so I guess that means I'm best off finding a schematic for something like a DK'Tronics memory expansion and just building one. So I guess, firstly, do they exist? And then I just have to find out where to get the edge connector. I don't think I've seen them sold anywhere in Australia.

[00WReX]

Hi All

I have a nice collection of Amstrad CPC's, 3 464's, 3 664's and 4 6128's, 2 CTM 644's and two LCD monitors rigged up to work with the CPC's. Plus I have a few spare 6128's for parts etc..

Cheers

Danny

Welcome Danny, great to see another Aussie with a nice CPC collection.
You have an impressive list there. Very nice 

Cheers,
Shane

[KaosOverride]

You have the Inicrom's Rambox diagrams for a 512kb expansion,  is just a 464 64kb expansion upgraded to 4 x 128kb chips.  You can build just with 1 or 2 128kb chips for an smaller expansion.


Does your 464 have the holes for centronic at the expansion bus?  Not 2.54mm but helps for soldering an internal expansion bus.  Will be a 50 cable hell soldering but you will be able to fit a second connector for an internal M4 Wifi for example. Because of different rev board layout is the best generic solution...

[AMSDOS]

On a side note, has anyone ever noticed that the 664 runs ever so slightly slower than a 464 or 6128?

Unfortunately I've never seen a real 664 running to know. Through Emulation I've noticed BASIC 1.0 running a little bit slower than BASIC 1.1, though a 664 has BASIC 1.1, this is the one everyone was trying to get for their 464 around 1989/90 before Amstrad put a stop to it, through Emulation the BASIC 1.1 for the 6128 doesn't work in 464 mode, unlike the 664 one, of course there could be other circumstances occurring within the hardware which maybe causing the 664 to run a touch slower, the BASIC 1.0 thing is always the 1st thing that springs to mind after doing a bit of coding in it, if you use a bit of memory through variables, arrays and AMSDOS was present, CATalogue a Disc shows a lag in displaying the contents of the disk unless those sorts of things have been CLEARed.

[rpalmer]

For those who are wondering what is going on with the 2 Mb memory expansion, well I have order some parts (namely the card edge connector and about 2 weeks ago) and still have about 3-4 weeks before I am likely to get them.

This means it maybe some time before I can get into serious production, but I have half built the first prototype which is MX-4 compatible as far as I can tell. This version may have to be wired to a dummy board to connect to my classic CPC, but i wish to avoid that as the number solder points on the dummy card would make it look like a botched job and ay also be difficult to find issue with it.

I have also started to design an "mini" version of the MX-4 which has just one slot for the boards, but can be "chained" together to suit how ever many boards you like. There is even one designed to supply the 5V when the CPC cannot.

rpalmer

[magnut]

I know Zaxon (Piotr Bugaj) has been seen making DK'Tronics clones and a similar mod to yarek as seen on Facebook but I don't think he sells them.

Schematics for a Dk'Tronics clone would be fine. I could at least make one then. I want at least another 64K to put onto the 464 and 664's I have... So I need to make at least two I guess.