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Open Source, DIY 512KB RAM Expansion

Started by revaldinho, 22:10, 24 April 18

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revaldinho

Quote from: aerobaticant on 09:25, 25 May 22Hi @revaldinho, and everyone. I have succesfully created a DIY version of the universal RAM expansion board on prototype PAD board! I changed the JTAG header to be a single in-line pin strip as this it what I have used on other projects using Xilinx devices.

I used an XC9536-15PC44 as I have a few lying around. Looking at the code, and using a 55ns SRAM, I couldn't see a reason why this shouldn't work, unless I've overlooked something important.


Looks great!

You must be a bit of a masochist to build on perf-board, because the project PCBs are easily sourced from many places and also can be had directly from Seeed. Still, it's a nice job. The point to point wiring looks very neat.

Your XC9536-15PC44 should be fine. All the speed grades for the XC9500s should work with all my projects. Even the slowest 15ns ones are way faster than the original LS TTL would have been. 

Quote from: aerobaticant on 09:25, 25 May 22Any suggestions of some good (6128?) games to try? ;)

I think the Batman Forever demo is the first thing to try - assuming that you have the 'right' CRTC  ;D

aerobaticant

I agree - there was a bit of masochism, but there's motive in my madness.

I am considering creating an updated version with a schematic (already drawn in KiCad ;) ) and using a newer CPLD.
The Atmel/Microchip ATF15xx family looks to be about the only option currently in production.
I'd also consider moving to an SMD version of the SRAM IC.

Any thoughts?

revaldinho

Yes, the ATF15xx seems like the only 5V compatible part available now, so it's a good choice. I have thought of porting some projects to it but haven't got round to it. The tool chain for Verilog looks a bit more convoluted than the Xilinx one.

As to whether to SMD or not, I just preferred to stick to through hole components to make my projects easy for anyone to build.  My more recent projects are mainly using just 74 series parts to avoid the need for any programming equipment altogether as well as being easy to solder. And they are very retro! The 512Kx8 is the largest SRAM available in through-hole though, so if wanting to do the 1MB or a larger card then I can see it makes some sense to move to SMD for that, where you can get the larger capacities in a single chip. 

Rabs

Hi, @revaldinho , just to say thanks again for the 512k old school ram expansion pack project. It worked :) and I now have a fully functioning 512k ram expansion.

Learnt a lot along the way.

Any recommendations on what next to try?

revaldinho

Quote from: Rabs55 on 17:39, 26 May 22Hi, @revaldinho , just to say thanks again for the 512k old school ram expansion pack project. It worked :) and I now have a fully functioning 512k ram expansion.

Learnt a lot along the way.

Any recommendations on what next to try?

Always good to hear about people building these projects for themselves.

If you want to build another in the same vein, then the EightROM is all 74 series too but you do need to be able to program your own (E)EPROMs or get hold of them pre-programmed from somewhere else. 

The project I want to recommend though is the CPC-CPLink card. Again it's all 74 series, so another easy build. It allows you to plug a Raspberry Pi right into the back of the CPC as a co-processor. Possibilities for expanding the CPC via the RPi are enormous and should offer a lot of coding fun. Since the CPlink card takes care of all the interface timing you can code in whatever language you like on the Pi. For example, @biged & I created a very simple GPU application providing the CPC with a second screen using BBC BASIC - see the latest posts in this thread and the screenshot attached showing the CPC output in a window on the Pi (full screen mode is possible too).

You cannot view this attachment.

Rabs

Great thanks, both projects look interesting.

Rabs

#156
Finally worked out how to upload images.  :)

Here is my trio of cards, the CPC-CPLINK (and just look at the size of the PI model B on the back), the Eightrom card and Old School 512k RAM expansion. All working.

I highly recommend these projects to anybody thinking about building them, the information and support is excellent. I have very little prior experience and found the projects challenging but fun and I have learnt so much along the way.
You cannot view this attachment.

netmercer

#157
Hi,
I'd like to buy a Universal CPC 512K RAM Card (the version with CPLD XC9536), which was developed by revaldinho.
Either a bare PCB or a complet card would be fine, regardless of which. Perhaps someone wants to sell such a device.

Best regards from Germany
netmercer

Rabs

#158
Quote from: netmercer on 00:01, 25 November 22Hi,
I'd like to buy a Universal CPC 512K RAM Card (the version with CPLD XC9536), which was developed by revaldinho.
Either a bare PCB or a complet card would be fine, regardless of which. Perhaps someone wants to sell such a device.

Best regards from Germany
netmercer

Hi, I could try and send you one of my spare PCBs from the UK, see my post in the classifieds.

Message me if interested.

revaldinho

Quote from: netmercer on 00:01, 25 November 22Hi,
I'd like to buy a Universal CPC 512K RAM Card (the version with CPLD XC9536), which was developed by revaldinho.
Either a bare PCB or a complet card would be fine, regardless of which. Perhaps someone wants to sell such a device.

Best regards from Germany
netmercer


If you're happy to build your own then please go ahead and take up Rob's offer for one of his spare PCBs.

I still build all my projects to order for CPCWiki members, and often make up one or two extras when I do. Right now I have one 512K universal card built and tested. So if you prefer the ready assembled option that would be £22 for the card and £9 for tracked postage to Germany. PM me for details.

Rev.


GUNHED

Quote from: Rabs on 11:17, 21 July 22Finally worked out how to upload images.  :)

Here is my trio of cards, the CPC-CPLINK (and just look at the size of the PI model B on the back), the Eightrom card and Old School 512k RAM expansion. All working.

I highly recommend these projects to anybody thinking about building them, the information and support is excellent. I have very little prior experience and found the projects challenging but fun and I have learnt so much along the way.
You cannot view this attachment.
Wow! This really looks awesome!!! 
Well, I also think about getting the CPC-CPLINK one day. How do you like it?
http://futureos.de --> Get the revolutionary FutureOS (Update: 2023.11.30)
http://futureos.cpc-live.com/files/LambdaSpeak_RSX_by_TFM.zip --> Get the RSX-ROM for LambdaSpeak :-) (Updated: 2021.12.26)

revaldinho




Well, if you'd like one I have at least one of those built up too - same deal as the RAM card £22 for the card + £9 for tracked postage to Germany. Pi ZeroW or Pi3A+ cards fit nicely on the back, but getting hold of those is a bit more problematic these days.

darkhalf


QuoteXC9536-15PC44 should be fine. All the speed grades for the XC9500s should work with all my projects
Unfortunately the only active Xilinx these days are the XL 3.3V series and those are in SMD versions. We use the XC9536XL on our Nistune automotive computer boards, but use a 3.3V drop down regulator to make them work with the 5V power. The IO on these still work with 5V ranges, which is good. 

You would need to rebuild the project to generate XL version JED files for programming with ISE (which is another story, since the Win10 doesn't support it)

I've had very mixed success lately with the older 5V XC9536 versions, with about half DOA or failing to program
CPC464/GT64, CPC464 Plus/CTM640, 2 x CPC6128/CTM644

waltermixxx

#163
Hi there,  I ordered 5 of the CPC 512K Ram Expansion, v1.10 (2018).  I started to solder in the parts I have around like caps and sockets, and I'm about to order the ram, the CPLD and the SIL0 and SIL1 resister networks.  I am having difficulty finding the Bill of Materials and I was wondering what value the SIL resisters are?  also any substitutions on the RAM Chip, incase I have difficulty finding it?   (the CPLD will have to come from ebay as digikey and mouser in canada do not seem to stock it.)   

Cheers. :) Pictures to come. :)

ok I found it in the Netlist: thinking sil0 is a 6.8k x 4 and sil1 is a 3.3k x 4  :)  I read the post on the schematic and how everything was in the netlist. :)  Cheers.   

r6k8_sil5   sil0 (
                    .common(VSS),
                    .p0(dip0),
                    .p1(dip1),
                    .p2(HIADR3),
                    .p3(HIADR4),
                    );
  r3k3_sil5   sil1
Amstrad CPC 464 + M4 :)

waltermixxx



SIL0=6.8 K  SIL1=3.3 K    could I use a 10K resister as SIL0 if I use a 4.7K as SIL1?   seems like the same kind of voltage divider?  would this work?  (I have 4.7 and 10 k in 5 pin SIL resister)  :)   

Amstrad CPC 464 + M4 :)

d_kef

Or you can make the resistor networks yourself, with discreet resistors.

d_kef

waltermixxx

That's a very good idea, and it did occur to me, but I wanted it to look nicer. :)  I'm in canada and ordering enough parts to make up 3 of these. :)  (now I just have to find a reputable place to get the CPLD :)     Cheers. :)
Amstrad CPC 464 + M4 :)

waltermixxx

so I purchased all my parts from digikey.ca except for the 9572 chip, and ordered it from:

https://www.ebay.ca/itm/272453077118 ( 5PCS XC9572-10PC44C Encapsulation:PLCC44,XC9572 In-System Programmable CPLD)

I hope they are reputable and I dont get fakes. :)

Amstrad CPC 464 + M4 :)

waltermixxx

So my CPLD chips arrived.  I Hope they are Good.  :0)
Amstrad CPC 464 + M4 :)

waltermixxx

I was able to program the CPLD's and verify,  so looks like they are good.  I'm surprised how quickly they arrived.  I have enough parts to build up 3 boards.  One I will keep, wondering if there is anyone in Canada with a CPC who might wish to buy one cost of parts and canada post. :)     (once i test the boards) :)  
Amstrad CPC 464 + M4 :)

waltermixxx

Amstrad CPC 464 + M4 :)

waltermixxx

#171
Here is my completed CPC464  :)  The M4 Board is connected also to the back of the Amstrad.  Now I just have to figure out how to run CPM on this. :) Question about the CRTC: 00 is this the good one? or the one that wont let me run batman?  :) very new to the CPC computers. :)

Amstrad CPC 464 + M4 :)

GUNHED

Congratulations! Now you can use advanced CPC OSes.  :) :) :)
http://futureos.de --> Get the revolutionary FutureOS (Update: 2023.11.30)
http://futureos.cpc-live.com/files/LambdaSpeak_RSX_by_TFM.zip --> Get the RSX-ROM for LambdaSpeak :-) (Updated: 2021.12.26)

d_kef

Quote from: waltermixxx on 00:32, 16 September 23Now I just have to figure out how to run CPM on this. :) 


Try HDCPM v1.10
It's just been released and supports your lineup.

d_kef

llopis

I'm working on a video about a similar RAM upgrade for the CPC and I was wondering what are some of the best demos/games/apps that showcase having more than 128KB of RAM. I already have FutureOS and SymbOS in the list. Anything else that you would say is really cool? Any dev environments (on the CPC itself) that can use that much RAM for something useful?

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