RAM Expansion Amstrad CPC464, help

[jesusdelmas]

Hi everyone!


I have been searching for 2 months a RAM expansion pack for my cpc464, but for the moment it is being very dificult to find a way to buy it or someone to make me one, so i decided to ask for some help.


I dont know what else i can do so any help will be very grateful 


Thanks in advance! regads

[shock__]

I recently upgraded my 464 to 6128 spec. You'd basically need parts for less than 5€ and a bit of soldering skills.

[jesusdelmas]

I recently upgraded my 464 to 6128 spec. You'd basically need parts for less than 5€ and a bit of soldering skills.

Oh cool, could you tell me what parts do i need and where to find it? i am kind of crazy with this hehe, a tutorial will be fine cuz i have never sold anything 


Anyway if someone knows where to find an Expansion Pack i will be 100% thankful 

[shock__]

If you're inexperienced with soldering I wouldn't recommend said modification as it involves socketing at least 1 chip and "piggybacking" 8 RAM chips.
Nothing overly complicated but certainly nothing I'd recommend for a first project.

[VincentGR]

If you're inexperienced with soldering I wouldn't recommend said modification as it involves socketing at least 1 chip and "piggybacking" 8 RAM chips.
Nothing overly complicated but certainly nothing I'd recommend for a first project.

I would like to see that schematic please.

[shock__]

Basically you'd apply all the differences between the 464 and 6128 schematics - which comes down to a GAL16V8 and a 74LS08 (IC118 & IC205). You'd have to lift 1 pin on the Gate array (!CAS) and 2 pins on IC109 (A14/A15) and connect them to the GAL outputs (A14OUT/A15OUT). Additionally you'll have to solder another 64k*1 DRAM onto the existing ones, with pin15 bent away and all 8 connected in series. !CAS0 goes onto pin15 of the original DRAMs, !CAS1 onto the bent away pins connected in series on the additional chips. Other signals can be tapped off existing chips (CPU or gate array has a majority of them available).
Somewhere on this board I've seen a proposed PCB that would plug between the CPU which would require just 5-8 wires being run across the board (I built mine on a seperate breadboard and had to run ~20 wires)

References:
http://www.cpcwiki.eu/imgs/4/4a/CPC6128_Schematic.png
http://www.cpcwiki.eu/index.php/PAL16L8

[Phantomz]

Has there ever been a clone / copy of the dk tronic memory expansion?

I've seen that " DDI3 USB floppy emulator for amstrad cpc 464 " which looks like a good upgrade for a standard 464, shame it doesn't include extra memory.

[rpalmer]

Phantomz,

There is the X-MEM which gives 512K RAM and 512K ROM by Toto, but he AFAIK is no longer building them.
I on the other hand is developing a much larger memory expansion and is in the process of testing the unit.

rpalmer

[shock__]

I've started a PCB layout for an internal 64K -> 128K expansion.
It's a small board you'd place between the socket and the actual CPU, reducing the number of wires required to be run across the board from ~20 to 8.
Once i'm happy with it I'll post the production files here and possibly do a small production run.

Preview:

[VincentGR]

Declaring interest 

[Audronic]

@shock__

If you PM Tot0 and ask him politely he may be able to make you up an X-mem.
He is still a member on this board
Good luck

Ray

[Bryce]

Has there ever been a clone / copy of the dk tronic memory expansion?

I've seen that " DDI3 USB floppy emulator for amstrad cpc 464 " which looks like a good upgrade for a standard 464, shame it doesn't include extra memory.

A real DKTronics 256K/512K clone would be nice to have, but I don't think anyone has ever reverse engineered the PAL.

Bryce.

[rpalmer]

Bryce,

Someone did put up the PAL equations for a replacement PAL around Oct-2015. I did not recall who did, but I did copy them into a text attached below.
You might say that it has been done.

Rpalmer

[Bryce]

That's the 6128 PAL. I am talking about the PAL that's used in the DKTronics RAM expansions.

Bryce.

[shock__]

Proposed final layout for the 6128 compatible 64k -> 128k expansion:


I'll open a seperate thread in the 'classified' section some time around this weekend to get a production run going.

[Bryce]

Looks good. I would have used SMD resistors and capacitors though. C1 will clash with the CPU socket at the moment.

Bryce.

[shock__]

IC2 and IC3 would also clash as the 'bars' at the ends of DIP40 sockets are 1.5 - 2 grids wide.
On the other hand, 1206/0805 SMD parts should fit on the proposed footprint for the decoupling capacitors (decided to make it all through hole for the ease of soldering for others - personally I've gone as far as QFP160)

[Bryce]

QFP160 is a pain in the arse to solder unless you're using a reflow oven.

Bryce.

[Phantomz]

A real DKTronics 256K/512K clone would be nice to have, but I don't think anyone has ever reverse engineered the PAL.

Bryce.

I agree, it would be nice to have a real DKTronics 256K/512K clone, I would prefer to have an easy to install external memory upgrade.

Hopefully the PAL will be reversed engineered one day. 

[Bryce]

I have a real DKtronics 464 256K expansion, so maybe I'll take a look at the PAL when I have time.

Bryce.

[jesusdelmas]

@shock__

If you PM Tot0 and ask him politely he may be able to make you up an X-mem.
He is still a member on this board
Good luck

Ray

Im in contact with him right now    i hope he can make me at least one. I would really apreciate it