DIY RAM EXPANSION

Nagging hardware related question? Post here!
User avatar
XorA
QL Wafer Drive
Posts: 1082
Joined: Thu Jun 02, 2011 11:31 am
Location: Shotts, North Lanarkshire, Scotland, UK

Re: DIY RAM EXPANSION

Postby XorA » Tue May 27, 2014 12:25 pm

1024MAK wrote:I hope y'all are not including the large numbers of helpful friendly Stardotters in this 'prickly' category :shock:


stardot is the jewel in the Acorn crown, awesome community there :-)

My expereinces were more in person with Acorn User Groups around Edin and Cambs!

G


User avatar
vanpeebles
Commissario Pebbli
Posts: 2706
Joined: Sat Nov 20, 2010 7:13 pm
Location: North East UK

Re: DIY RAM EXPANSION

Postby vanpeebles » Tue May 27, 2014 12:25 pm

No I was speaking more historically of the 32-bit scene. Stardot and the 8 bit Acorners are a good bunch :)


User avatar
1024MAK
Super Gold Card
Posts: 584
Joined: Sun Dec 11, 2011 1:16 am
Location: Looking forward to summer in Somerset, UK...

Re: DIY RAM EXPANSION

Postby 1024MAK » Tue May 27, 2014 12:42 pm

Thanks for the clarification everyone :D

Mark


QL, Falcon, Atari 520STFM, Atari 1040STE, more PC's than I care to count and an assortment of 8 bit micros (Sinclair and Acorn)(nearly forgot the Psion's)
User avatar
Dave
SandySuperQDave
Posts: 2736
Joined: Sat Jan 22, 2011 6:52 am
Location: Austin, TX
Contact:

Re: DIY RAM EXPANSION

Postby Dave » Tue May 27, 2014 7:17 pm

As a Risc PC 700 owner (it is faulty, and I miss it so, so much) I have been out of that community since the 90s, but used to write for Archive. My preferred PCB design platform is ArcPCB.

Who knew?


msch
ROM Dongle
Posts: 8
Joined: Thu Sep 25, 2014 9:59 pm
Location: Frankfurt/Germany

Re: DIY RAM EXPANSION

Postby msch » Thu Sep 25, 2014 10:16 pm

tcat wrote:I am sharing back my work as you helped me with it.
It is not perfect, yet functional on my QL.


Hi Tom,

Great work! Is it possible to get the cad-files? In the german Sinclair forums we want to make a small batch of professional produced pcbs (approx. 10 pcbs) and it would be great to have the (eagle?) files.

Best regards

Mathias


User avatar
bwinkel67
Aurora
Posts: 936
Joined: Thu Oct 03, 2019 2:09 am

Re: DIY RAM EXPANSION

Postby bwinkel67 » Tue Feb 11, 2020 6:38 am

I'm planning on giving tcat's board a try by etching my own PCB board and then populating it and getting the GAL properly configured. Seems like there was a brief discussion on an improvement on it with regard to interference but no new info that I found. I downloaded all of tcat's files (PDF's, eqn, and jef) and from that it seems pretty straightforward.


User avatar
Popopo
ROM Dongle
Posts: 33
Joined: Wed Apr 07, 2021 10:37 am

Re: DIY RAM EXPANSION

Postby Popopo » Sun Jan 16, 2022 3:02 pm

prime wrote:And just to keep people updated...

My internal version is now working, I had a couple of issues with the PLD as I wanted to use different pins, and converted the source from PALASM to WinCUPL, but working now.

I also had to remove and replace the (red) double height CPU socket and replace with a couple of 24 pin turned pin sockets, but that was easy enough as I have a desolder gun.

Picture here : https://www.facebook.com/media/set/?set=a.10202509089060733.1073741835.1000448675&type=1&l=235ce2f002

Cheers.

Phill.


Hi Phill,
I saw a same of your work and I want to get one :)

Is there any option to get a PCB or the whole module?

Thanks.


User avatar
Chr$
Aurora
Posts: 993
Joined: Mon May 27, 2019 10:03 am
Location: Sachsen, Germany
Contact:

Re: DIY RAM EXPANSION

Postby Chr$ » Thu Jun 23, 2022 3:49 pm

Digging up this thread again because I had some internal RAM PCB's made based on the design/discussion here but using SMD RAM chip and GAL, so that it can be fitted without having to change the CPU socket and without rubbing up against the ZX8301. A mistake was made on the PCB and one of the GAL pins wasn't connected to anything instead of going to the CPU, so the black wire is a bodge to make it work (and it does work).

20220623_163438.jpg


Before I get changes made I had the idea of adding a switch to the side with access to it through the expansion port (with a long poky thing!) so that if the QL is to be used with external RAM, the internal module can be turned off and there would be no need to open it up/remove it from the fragile CPU socket.

So my question(s) to the members here who understand more about these things than I do: It is possible and to disable such a board and would it just be a case of adding a switch to break the connection between the 5v that comes from pin 13 of the CPU, before it gets to the RAM and GAL ICs? Or would one also need to break the connection between GND and the RAM and GAL?

And if anyone wants one of these boards (with the missing GAL connection that needs to be bodged) for just the cost of postage, let me know.


https://QXL.WIN
Collector of QL related computers, accessories and software, even though I don't really understand how they work!
Original QL's: many (plus quite a bit of other old stuff and 180+ original software titles)
Custom XT cased QL system with Gold Card, Qimi mouse, Hermes and MFM HDD
QXLII card installed in a PC
Q40 and Q68 also present

Ask me about felt pads - I can cut them to size and they have proved excellent for mdv data recovery.
martyn_hill
Super Gold Card
Posts: 714
Joined: Sat Oct 25, 2014 9:53 am

Re: DIY RAM EXPANSION

Postby martyn_hill » Thu Jun 23, 2022 4:56 pm

Hi Chris!

Looks great :-)

As for a 'disable' feature, I have done this before (for a very different RAM Expansion design) by allocating a pin on the GAL for the purpose and adjusting the decoding logic to take account of the state of this input.

Happy to share my (far inferior) design via PM, should that be of any use...

Good luck!


User avatar
Chr$
Aurora
Posts: 993
Joined: Mon May 27, 2019 10:03 am
Location: Sachsen, Germany
Contact:

Re: DIY RAM EXPANSION

Postby Chr$ » Thu Jun 23, 2022 10:16 pm

martyn_hill wrote:Hi Chris!

Looks great :-)

As for a 'disable' feature, I have done this before (for a very different RAM Expansion design) by allocating a pin on the GAL for the purpose and adjusting the decoding logic to take account of the state of this input.

Happy to share my (far inferior) design via PM, should that be of any use...

Good luck!

That sounds interesting Martyn, but I'm not sure I'd be clever enough to implement it! And I certainly have no idea how to write logic for GALs. Very happy to take a look though.


https://QXL.WIN
Collector of QL related computers, accessories and software, even though I don't really understand how they work!
Original QL's: many (plus quite a bit of other old stuff and 180+ original software titles)
Custom XT cased QL system with Gold Card, Qimi mouse, Hermes and MFM HDD
QXLII card installed in a PC
Q40 and Q68 also present

Ask me about felt pads - I can cut them to size and they have proved excellent for mdv data recovery.

Who is online

Users browsing this forum: No registered users and 10 guests