As always promised I just have published the iRAM/640 repository with the Gerbers and JED files for the GALs, so now everybody can start building the expansion:
https://github.com/etomuc/CPC6128_iRAM-640
The documentation is still minimal and will be improved if necessary. For any questions or required clarifications please use this thread here.
Thanks a lot for that.
It seems to be the perfect new year gift for my 6128. :D
d_kef
And PCBway... 8)
Excellent service for the CPC community. Can't wait to try building it coming weeks!
Now I wonder if someone would like to build a batch, I would buy one or two more for sure.
What is the cheapest way to program ATF16v8?
TLL866II-PLUS with new Firmware 12.xx cost ~50$
Can it be cheaper?
Quote from: eto on 00:00, 30 January 25As always promised I just have published the iRAM/640 repository with the Gerbers and JED files for the GALs, so now everybody can start building the expansion:
https://github.com/etomuc/CPC6128_iRAM-640
The documentation is still minimal and will be improved if necessary. For any questions or required clarifications please use this thread here.
Excellent work, thanks. I have some PCBs on order.
Are the instructions on the repository still relevant, in light of current discussions in the main thread?
Now main tread is about ext for cpc464.
Quote from: dodogildo on 12:37, 31 January 25Are the instructions on the repository still relevant, in light of current discussions in the main thread?
The other thread is about the ongoing development - currently it's about the edition for the 464 and 664.
@eto is there any reason why you did not socket all the ICs. Just wondered before I start to build.
Quote from: Rabs on 22:54, 13 February 25@eto is there any reason why you did not socket all the ICs. Just wondered before I start to build.
The reason is space. It's a tight fit in the 6128 and with a socket the keyboard casing might touch the ICs and put pressure on the expansion. For the CPU I could move the socket just far enough so it will be behind the keyboard.
I'm not 100% sure any more if it's really impossible to use sockets as Prodatron mentioned that he could even fit the expansion under the metal shield of a German 6128 and I was convinced that it would not fit.
@eto just checking the GitHub repository lists 22uF in the BOM but the silk screen has 10uf. Guess it does not really matter.
(about:invalid)
(about:invalid)
@eto all working. Great thanks. I did socket the ICs on my first go, just to make sure I got the PALs programmed ok but as you suggested it does not quite fit. Will do the next one as per your instructions. :D
Great GitHub repository. Many thanks for the hard work and sharing.
Quote from: Rabs on 18:01, 14 February 25@eto all working. Great thanks. I did socket the ICs on my first go, just to make sure I got the PALs programmed ok but as you suggested it does not quite fit. Will do the next one as per your instructions. :D
Great GitHub repository. Many thanks for the hard work and sharing.
AWESOME! Thanks for your feedback.
I'll add the information that it's a good idea to have one PCB with sockets to test the PAL programming. I also did that.
Quote from: Prodatron on 19:17, 30 January 25Now I wonder if someone would like to build a batch, I would buy one or two more for sure.
And I would like to buy two of them too. Bigger batch, smaller price. :)
@eto all done as per your instructions and fits under the keyboard nicely.
20250219_205521~2.jpg
The only dilemma I had was what type of pin header to use. Standard pin headers seemed a bit thick. In the end I used Samtec TS-120-T-A (https://www.digikey.co.uk/en/products/detail/samtec-inc/TS-120-T-A/1105474).
They have a thinner and smaller insertion pin when compared to standard header pins but you have to be very careful when inserting into the original Z80 socket. In the end, I removed the main PCB from the case to make sure I aligned the pins correctly.
20250219_205532~2.jpg
Quote from: Rabs on 22:06, 19 February 25@eto all done as per your instructions and fits under the keyboard nicely.
20250219_205521~2.jpg
What a clean CPC!
I just love the iRam640.
Another happy customer :D
20250221144842.jpg
20250221150317.jpg
d_kef
Need a nice badge for the case now. My sticky label does not do it justice ;D
20250221_143239.jpg
You need a new badge that says "Amstrad 640k Colour Personal Computer" ;-)
Maybe Badge Man can do that: https://www.retro8bitshop.com/
https://www.cpcwiki.eu/forum/hardware-related/wip-internal-512k-expansion/msg242825/#msg242825
https://www.cpcwiki.eu/forum/hardware-related/wip-internal-512k-expansion/msg242898/#msg242898
;D :laugh:
@Rabs and
@d_kef ! You have 120ns ram from new. :o
Quote from: McArti0 on 18:03, 21 February 25@Rabs and @d_kef ! You have 120ns ram from new. :o
I've seen 2 or 3 v2 6128 motherboards in the past and all of them had 120ns RAM chips.
d_kef
Amazing work. I have some PCBs on order. @eto, is there any chance you can create a part list on Mouser and add to the repository? That'd help us less experienced a lot.
I tried my best to find the components on Mouser and updated the Github page. I am not sure that these are really the right components as I am not really familiar with all the different meanings of the specs, so there is a slight chance this is not perfectly right.
I added a request to the page that if someone figures out all the items that they would please share the list.
If the two PAL are aligned with the CPU, may be it is possible to socket them too?
Quote from: Egg Master on 19:00, 28 February 25If the two PAL are aligned with the CPU, may be it is possible to socket them too?
You can socket PAL1 but PAL2 will (probably) clash with the keyboard if you are adding a socket. There is just not enough space in the 6128 to socket them both.
I'm actually happy that it worked out to use a socket for the CPU.
Quote from: Rabs on 15:35, 21 February 25Need a nice badge for the case now. My sticky label does not do it justice ;D
20250221_143239.jpg
I think this is more suitable.
I tried to match the typeface and the colour of the original 6128 badge but the colour depends on the paper you use and I've had only plain paper available to test.
Anyway I attach here the PDF and the XCF file for anyone who wants to try it or has the ability to make a colour accurate copy.
20250305_204304.jpg
20250305_204345.jpg
d_kef
@d_kef /
@eto , that looks so great and fits to the old style! :)
Oh, I love it!
Quote from: d_kef on 19:55, 05 March 25Anyway I attach here the PDF and the XCF file for anyone who wants to try it or has the ability to make a colour accurate copy.
Would you mind if I add it to the repository? Or should I just add a link to the post here?
Quote from: eto on 22:01, 05 March 25Oh, I love it!
Quote from: d_kef on 19:55, 05 March 25Anyway I attach here the PDF and the XCF file for anyone who wants to try it or has the ability to make a colour accurate copy.
Would you mind if I add it to the repository? Or should I just add a link to the post here?
Of course you can add it to the repository!
I'm glad you like it.
d_kef
The new version for the 464/664 works fantastic so far:
Unbenannt2.jpg
I have to do some more tests but also use the opportunity to fix some things in my 664 :)
Thanks a lot,
@eto for this great hardware!
Quote from: Prodatron on 22:41, 12 March 25The new version for the 464/664 works fantastic so far:
I love to see that.
(but this is the wrong thread for the 464/664 version ;) )
Here goes another one 8)
(https://i.ibb.co/SDQGPDrs/dodoiram02.jpg) (https://ibb.co/kV3vxV1H)
(https://i.ibb.co/vC4dQKWK/dodoiram03.jpg) (https://ibb.co/cKh8C797)
(https://i.ibb.co/qYP0MSJH/dodoiram04.jpg) (https://ibb.co/s9M5vfWT)
Congrats!
Very clean work and also great view.
Quote from: dodogildo on 19:00, 07 April 25Here goes another one 8)
Very cool
@dodogildo , glad to see people building this great project, we need more of this! :)
Quote from: Prodatron on 20:21, 07 April 25Quote from: dodogildo on 19:00, 07 April 25Here goes another one 8)
Very cool @dodogildo , glad to see people building this great project, we need more of this! :)
You could manage the creation of a batch of this great internal RAM expansions. You did that with many projects before and have the experiences for that. :)
Buy it on ebay now:
https://www.ebay.de/itm/127030209562?itmmeta=01JRJMYT875S34Z2S8QFYRWHE4&hash=item1d93972c1a:g:KpkAAOSwCm1n5rCT
Quote from: Prodatron on 20:21, 07 April 25Quote from: dodogildo on 19:00, 07 April 25Here goes another one 8)
Very cool @dodogildo , glad to see people building this great project, we need more of this! :)
Another one build from
@dodogildo Thanks a lot
@eto And of course special thanks for
@dodogildo Almost ten more people waiting dodogildos work in Turkey.
(https://i.hizliresim.com/rbhlcoz.jpg) (https://hizliresim.com/rbhlcoz)
(https://i.hizliresim.com/hn8wbn2.jpg) (https://hizliresim.com/hn8wbn2)
8 units more...
https://www.ebay.de/itm/127051800106
Sadly in red, I would love to see them in blue ;) :)
Quote from: GUNHED on 13:12, 15 April 25Sadly in red, I would love to see them in blue
Red, blue, purple, black, white, ... All these colours look wrong over the green CPC mainboard.
Quote from: GUNHED on 13:12, 15 April 258 units more...
https://www.ebay.de/itm/127051800106
Even though they look nice, I think precision sockets are the wrong choice. It's a bit difficult to plug in and out the ICs without damaging their legs.
Quote from: dodogildo on 22:16, 15 April 25I think precision sockets are the wrong choice.
I still doubt sockets are a good idea anyway (except for the CPU).
But let's see. I think Prodatron ordered one and if I am not mistaken he can report soon if the version with sockets still properly fits into a 6128.
Quote from: eto on 23:28, 15 April 25But let's see. I think Prodatron ordered one and if I am not mistaken he can report soon if the version with sockets still properly fits into a 6128.
I should receive it end of april. It will be interesting to see, if the metallic shield, which is used in german CPCs, still fits with the sockets.
Quote from: Prodatron on 09:38, 16 April 25It will be interesting to see, if the metallic shield, which is used in german CPCs, still fits with the sockets.
@unay is now using a german CPC with a fully-socketed iRAM. But I don't know if he had to modify the metallic shield or not.
The price on eBay is expensive, to just produce an existing design (eto's real work)... After all, the Poles have made a specialty of doing business with the retro computers interfaces for a decade. I hope that someone in the cpcwiki community will give his contribution to make it affordable.
Quote from: dodogildo on 09:46, 16 April 25Quote from: Prodatron on 09:38, 16 April 25It will be interesting to see, if the metallic shield, which is used in german CPCs, still fits with the sockets.
@unay is now using a german CPC with a fully-socketed iRAM. But I don't know if he had to modify the metallic shield or not.
I'd pull out the shield two months ago. But since i saw prodatron's comment i wonder if it fits :)
So i'm gonna try it to night.
Quote from: Egg Master on 10:05, 16 April 25The price on eBay is expensive, to just produce an existing design (eto's real work)... After all, the Poles have made a specialty of doing business with the retro computers interfaces for a decade. I hope that someone in the cpcwiki community will give his contribution to make it affordable.
If you check out the GitHub repository then you can see that I encourage (semi-)professional resellers to build that expansion.
This guy specifically asked for permission. He's using components from reliable resellers and high quality sockets which costs of course more than if you buy everything on AliExpress. He has a (close to) professional lab where he produces everything. That expansion looks like it's done in a professional factory. I'm totally fine with him earning a few bucks per item.
I don't see the connection between what I'm saying and your answer. This project is on GitHub, so your approval is no longer required and you probably don't know his purchase costs. Anyway, his other items for sale on eBay confirms what I thought. I'm just saying he was doing retro buisness and I hope someone on cpcwiki will do it more atractive for the community. :)
Don't treat these guys time and effort as free. They're not scalpers. They're doing the work so you don't have to, so it's extremely rude to expect them to charge only the part cost. It's not like they'll be buying a yacht from the proceeds. You've probably bought them a few coffees.
If you don't like the price, don't buy it. If you think you can make it cheaper, then by all means, do so.
Quote from: Egg Master on 14:11, 16 April 25and you probably don't know his purchase costs.
I do. He asked if it's fine to sell it for that price and he shared which components he bought from Mouser.
He also has to cover Ebay fees, taxes and has the risk of returns. You can't compare all of that to someone who builds a batch for fun and sells it here on the forum.
It's a bit on the pricier side, agreed. And I hope some professional seller will eventually offer it for <30€. That should be feasible.
Quote from: Egg Master on 14:11, 16 April 25I don't see the connection between what I'm saying and your answer.
It seemed you don't agree with him selling it at that price. I do agree with him and I explained why.
And I would of course love to see that someone builds a batch with cheaper components and then sells it for e.g. 15€ on the forum.
Offtopic:
- Everybody is totally fine with earning money at the job or the own company.
- Everybody is totally fine wasting spending money for lots of things.
Can somebody please tell me why CPC users are not allowed to make some money or just cover their costs?
Fun thing: The persons contributing lots of stuff (hardware, software, art, graphics, music, and, and, and...) seem to have no problems with this. So ... why do others have problems if somebody earns a few Euros here and there?
From a personal perspective I can only tell: Everybody is free to buy or not to buy an given offer.
I'm rather annoyed by your interpretations... For the third time:
I hope someone in the CPC community will offer it at a fair price.
I don't care if people who trade retro make money. :picard:
Quote from: unay on 10:32, 16 April 25Quote from: dodogildo on 09:46, 16 April 25Quote from: Prodatron on 09:38, 16 April 25It will be interesting to see, if the metallic shield, which is used in german CPCs, still fits with the sockets.
@unay is now using a german CPC with a fully-socketed iRAM. But I don't know if he had to modify the metallic shield or not.
I'd pull out the shield two months ago. But since i saw prodatron's comment i wonder if it fits :)
So i'm gonna try it to night.
Unfortunatly it doesnt fit with metalic shield.
The shield has curved structure because of the keyboards tilt.
It start high at the rear of board but ends low at front.
Because of that the iRAM touches shield. You have to bend the shield for installation.
Maybe
@Prodatron has another solution when iRAM arrives.
(https://i.hizliresim.com/a17cjmd.jpg) (https://hizliresim.com/a17cjmd)
Low profile socket needed
Quote from: McArti0 on 10:57, 17 April 25Low profile socket needed
can you recommend one?
115-93-640-41-003000
I have used some ultra low profile sockets for a recent project but they are expensive.
You can see the difference. These are 28 pin. Sametc ultra low profile ICO. Don't know if you can get them in the required DIP size.
20250325_185152.jpg
I wonder if it fits in the GX4000? :P
Probably going to make some of these shortly - anyone else in Australiatown interested?
Quote from: pelrun on 06:48, 21 April 25I wonder if it fits in the GX4000? :P
Gx4000 is on my personal wish list - but much more work needs to be done incl. learning to use bigger CPLDs - more logic is required and the space is very restricted.
At the moment: please don't even try it.
It won't fit - and it will clash with the ASIC access.
There's no real point for more than 128k on the GX4000 anyway (...for now), and that's easily enough done by piggybacking the DRAM. So yeah, I wasn't entirely serious :)
Quote from: pelrun on 10:05, 21 April 25There's no real point for more than 128k on the GX4000 anyway (...for now), and that's easily enough done by piggybacking the DRAM. So yeah, I wasn't entirely serious :)
I see a demand for plug&play 128K upgrades. Piggybacking is easy enough for some but not for the majority.
And if you put in a SRAM anyway you can also do 512K and run Mighty Steel Fighters on a GX4000 without too much effort ;-)
That would be the height of the GX4000, knowing that such a game uses 512K of RAM because no cartridge.
Quote from: Egg Master on 18:10, 16 April 25I'm rather annoyed by your interpretations... For the third time:
I hope someone in the CPC community will offer it at a fair price.
I don't care if people who trade retro make money. :picard:
Well, I suggest to come back to the topic (see first line of page please). Thanks! :)
Quote from: eto on 12:18, 21 April 25And if you put in a SRAM anyway you can also do 512K and run Mighty Steel Fighters on a GX4000 without too much effort ;-)
Many of us GX4000 users would love to learn about this mod. Got any tutorials? ::)
Quote from: dodogildo on 21:06, 25 April 25Quote from: eto on 12:18, 21 April 25And if you put in a SRAM anyway you can also do 512K and run Mighty Steel Fighters on a GX4000 without too much effort ;-)
Many of us GX4000 users would love to learn about this mod. Got any tutorials? ::)
It does not exist (yet). That was just a response to the comment you can achieve 128k by piggy backing the RAM.
I meant that I still see a demand for a solution which does not require soldering - and if that is done anyway you can go for 512K as there is no benefit of adding only 128k.
But it's just a hypothetical discussion (for now).
Got one of these IRAM640s off eBay a week or so ago. Just tried it in the 6128 today and it appears invisible - ram remains at 128k in Noels tests and in symbos. What have I missed or are their fake ones of these going about?
Quote from: Blank_Reg on 21:49, 06 July 25Got one of these IRAM640s off eBay a week or so ago. Just tried it in the 6128 today and it appears invisible - ram remains at 128k in Noels tests and in symbos. What have I missed or are their fake ones of
Which offer on Ebay is it?
Can you take pictures of it? How it is installed and backside and frontside of the iRAM. Also a picture of the upper RAM test screen of Amstrad diagnostics.
I doubt that anyone would sell fakes of them. Building something that looks like the iRAM with fake chips and without a total failure of the CPC would be quite time consuming and would require much more effort than building the real thing.
If it's a real iRAM 640 then if anything would be malfunctioning the whole CPC would be dead as it decouples a few signals that are crucial. That your CPC 6128 is working means that also the main functionality of the iRAM is working.
There are basically 2 things I can imagine that could cause it to appear as 128K in SymbOS and Amstrad Diagnostics:
1) the disable switch is closed. Then the iRAM becomes invisible and the CPC 6128 is a pure 6128 again
2) The SRAM is not working (fully). In that case Amstrad diagnostics should show a large gap on the upper RAM test before it shows some RAM again.
Many thanks. Wasn't aware of a disable jumper - is that on top or bottom of the daughter board? Would maybe explain how the thing even boots at all if it was faulty. I'll have a check tomorrow when I'm able to access the unit. I have another 6128 I can check it with as well.
Quote from: Blank_Reg on 18:02, 07 July 25Many thanks. Wasn't aware of a disable jumper - is that on top or bottom of the daughter board? Would maybe explain how the thing even boots at all if it was faulty. I'll have a check tomorrow when I'm able to access the unit. I have another 6128 I can check it with as well.
Depends on the revision. The early version has it on the bottom the second revision on top. It's usually not populated as there is no known (common) situation where it would have been required to disable it.
On the right I can see a DIS where a jumper block might have been intended to have been soldered but it's clear (i.e. not shorted and not soldered). The CPU is a little unusually compared to the routine Zylog and SGS Z80's seen in that it is a NEC D780C-1. The board also has the AMSPARA v1.2 Amsdos / Parados dual ROM installed (I've tried with both ROMs).
Right I've taken all the chips out and put them back in including the CPU and it's now saying 640KB in the Diag Test, though testing upper RAM only seems to test Bank 07, skipping the rest. Then when I test Lower RAM, it reverts to telling me I only have 64KB again, removing the option to test Upper RAM!
Quote from: Blank_Reg on 16:14, 08 July 25and it's now saying 640KB in the Diag Test, though testing upper RAM only seems to test Bank 07, skipping the rest. Then when I test Lower RAM, it reverts to telling me I only have 64KB again, removing the option to test Upper RAM!
Can you take a picture of the open CPC with the board installed?
And the results of the upper RAM test?
(if you can't upload here just click on "Preview" button, then the upload button appears)
Since the Amsdiag saw the right amount of 640K at least once I would expect that there is an issue with the RAM IC. Either it's really malfunctioning or (more likely) a loose connection. Is the IC socketed or soldered?
Showing 640 (briefly)
Upper test
On the board
Based on that I would expect that one of the ICs is malfunctioning or that there is a short somewhere on the PCB. Unfortunately Amstrad Diagnostics is not very useful to identify if the address logic of an expansion misbehaves. Depending on the error it report all kind of weird values. And what I see here is definitely weird.
If the seller has tested the module before shipping then it might just be a loose IC. You can try and remove all ICs from their sockets and insert them back again.
After having that done you can try again with Amsdiag. If you can change the ROM I would recommend to use the more recent 1.3 or 1.4 version.
https://www.cpcwiki.eu/index.php/ROM_List#Background_Utility_ROMs
(1.4 is available directly on that page, last column. 1.3 will be available when you follow the link to the Github repository)
Just recently I have also written a minimal RAM Test in BASIC. Unfortunately I can only find the screenshot at the moment. It's just a few lines though. Output should be like in the screenshot attached (but only until 10, the rest should be --). This might give a bit more clarity what is going on.
However, if the reseating does not resolve it, you should open a Ebay case and ask for a replacement or refund. I could imagine that one of the ATF chips is not fully working. They are definitely not from the same batch and that kind of difference could be a sign that they are recycled ICs coming form a cheap source like AliExpress. While that is not necessarily bad, if he did not test the expansion it might have slipped through that a pin is malfunctioning.
btw: where are you located?
That's very useful information indeed - many thanks!
I'm going to send the module back to the vendor so they can test, but I suspect one of the two ICs or the RAM itself (tho I normally find a RAM chip is either working or is completely dead, not just semi working). One of the ICs under a magnifying glass looks like it might have a funny 'leg'... I've done the prise and reseat on the chips - this is what got me from nothing to semi working before, though after a power off /on, that went again.
I had another one on order from a vendor in Poland, though this seems to be a non starter as it's been at least 4 months now and nothing has materialised...
I'm located in Southport. I've spent the last 2 years or so building up a collection and have got far too much kit now tbh! I recondition it and restore it usually. I'm a systems architect and HPE engineer by trade - used to deploy blade system, simplivity, alletra etc etc
I don't have a ROM programmer/ kit for the latest build unfortunately. Maybe my next thing to get and learn (flashing ROMs is so easy on modern equipment I'm spoilt tbh).
Quote from: Blank_Reg on 21:39, 09 July 25I'm located in Southport.
I don't have a ROM programmer/ kit for the latest build unfortunately. Maybe my next thing to get and learn (flashing ROMs is so easy on modern equipment I'm spoilt tbh).
I'm down on the South Coast. Think I have spare PCBs and parts if you want a go at building your own. The programmers are not too expensive. Message me if you need help.
Rabs
My feeling is that the vendor can sort out or refund the i640. If I can't get hold of one after that then build your own could be a viable option, thanks.
As for the dual Amsdos / Parados ROM, I'm all ears if you can burn an up to date replacement, obviously name your costs.
Cheers.
Quote from: Blank_Reg on 21:39, 09 July 25but I suspect one of the two ICs or the RAM itself
Yes, the RAM is less likely as at least one bank can be tested and if the SRAM was just malfunctioning you should see bank 8 being available in AmsDiag but never bank 7.
However, it might also be related to the 74hct174 IC. If you do have a multimeter you can test the connections between SRAM and 74HCT174 that select the 64K page. Maybe there's an issue.
If there's no connection issue, you can check if A16-A18 are set correctly if selected:
In BASIC just type
out &7f00,&c4 => A16-A18 should be 0
out &7f00,&cc => A16 should be 1, all others 0
out &7f00,&d4 => A17 should be 1, all others 0
out &7f00,&e4 => A18 should be 1, all others 0
out &7f00,&fc => A16-A18 should be 1
On PAL2, 3rd / 4th from right to left bottom row looks iffy; bent. I'll test with multimeter on reverse pin.
I'll test A16 - A18 on Friday when I have a chance with multimeter.