Schneider cpc 464 with ddi3 crashes on true color effects

[wietze]

Ive recently gotten a Schneider cpc 464 and subsequently obtained a ddi3.


I tried to run a few demos, on which I experienced crashes on true color effects. The machine/demos seems to crash consistently when they are displayed (for example the Batman Forever demo).


I tried to dig into this issue and found one related topic on this board (http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/wanted-working-memory-expansion-for-cpc-464/), but being new to the amstrad, I did not find any conclusion on as how I could deal with this issue. Does the problem lie inside the cpc 464, does it lie within the memory expansion (ddi3?).


Can any expert elaborate on this issue (if its a known issue) and perhaps suggest me a remedy (if applicable)?


Kinda regards
Wietze

[LambdaMikel]

There seems to be some confusion - the DDI3 itself does not contain any memory expansion AFAIK.
I believe there is a memory expansion add-on board that plugs into the DDI3. I don't know that one though.


It can be a combination of many factors. The highest success rate is with @revaldinho 's memory expansion.

[wietze]

Ok, so the ddi3 I have also has a memory expansion board added.

Is your suggestion to remove the expansion board and use the memory expansion you mentioned? Where can I obtain said expansion; is it suitable for the CPC464 and can it easily be combined/used with the ddi3?

[LambdaMikel]

Ok, so the ddi3 I have also has a memory expansion board added.

Is your suggestion to remove the expansion board and use the memory expansion you mentioned? Where can I obtain said expansion; is it suitable for the CPC464 and can it easily be combined/used with the ddi3?

First I would run a memory check and see if the memory board is good.


If not, or it was advertised that C3 mode should be working with it, I would either return it to the seller or ask for a replacement.


In any case, if you wanted to use @revaldinho 's expansion, you would need to disconnect the DDI3 ram expansion.
@revaldinho 's expansion works very well together with a plain DDI3; he is using one himself (and I do too). But you would also need a MotherX4 or other backplane connector.

Also check the CPC thoroughly before buying anything else.
- clean the expansion port
- replacing the Z80 CPU also helps sometimes
- the DDI3 cardboard edge connector is inherently wobbly. Make sure the connections are really good.

[wietze]

First I would run a memory check and see if the memory board is good.

I ran the memory test that Duke posted in abovementioned thread. I had the following results; which I thought were good (note, last test didnt terminate with the `press any key'):
http://frummel.org/~weedz/atari/pics/cpc3.jpg
http://frummel.org/~weedz/atari/pics/cpc2.jpg
http://frummel.org/~weedz/atari/pics/cpc1.jpg

[wietze]

I just checked, the Ad from Zaxon states its Dk'Tronics compatible 512kb memory expansion. I cannot judge, but are the memtest results I posted consistent with the behaviour one would expect from the Dk'Tronics; because that could rule out the memory expansion as the culprit?

[wietze]

I took the time to follow your other advice, and actually cleaning the contacts made a difference!


I can confirm the PhX (albeit with some unstable fullscreen parts) demo working, which before would crash on me. Batman Forever however still craps out on the truecolor part.

[revaldinho]

@wietze, the second picture in your RAM test results shows that the RAM card you got with the DDI-3 doesn't perform the same as a CPC6128 in the C3 mode. The 'ROM-remapped' message means that it's doing what all DK'T compatible cards do, and you are reading ROM data instead of expansion RAM data from some addresses. So anything that needs the C3 mode, like Batman or FutureOS, won't run on a 464 with that card, but otherwise the card may well be a good Dk'Tronics compatible one which is enough to run the vast majority of CPC software.



I think my universal card is still the only one which implements the full Amstrad C3 mode on a 464/664 - you lose 64K when you run in this 'shadow' mode, so the 512K expansion becomes 'only' 448K, but that's certainly enough to run the full Batman demo and indeed FutureOS. Details are in the release notes for the CPLD firmware on GitHub. As it happens I have just got hold of some xc9536 CPLDs which means I can build some more. I see you have PM'd me so I'll get back to you there, and anyone else wanting one should drop me a PM too.



The more problematic bit is attaching the RAM card to your machine. It uses a box connector like all the other modern peripherals, e.g. the M4 card etc so you need an expansion card to plug it into, and because the DDI-3 doesn't have a pass through you need an expansion card with an edge connector which will allow to plug the DDI-3 at the end.

[LambdaMikel]

The more problematic bit is attaching the RAM card to your machine. It uses a box connector like all the other modern peripherals, e.g. the M4 card etc so you need an expansion card to plug it into, and because the DDI-3 doesn't have a pass through you need an expansion card with an edge connector which will allow to plug the DDI-3 at the end.

@wietze
check out LambdaBoard which does exactly this... PM me if you would like one.


You can also build it yourself if you have the parts, order the PCB here:

https://www.seeedstudio.com/LambdaBoard-Expansion-Board-Backplane-for-Amstrad-CPC-Computers-g-1143632



https://statics3.seeedstudio.com/seeed/img/asset/15312473655447.jpg

[wietze]

The more problematic bit is attaching the RAM card to your machine. It uses a box connector like all the other modern peripherals, e.g. the M4 card etc so you need an expansion card to plug it into, and because the DDI-3 doesn't have a pass through you need an expansion card with an edge connector which will allow to plug the DDI-3 at the end.

I found this on the internet: https://www.sellmyretro.com/offer/details/cpc-mother-x4-connectors-32490 but seems to be out of stock. Does the creator of this reside on this forum, or are these schematics perhaps public? Or do you guys know of any other resellers of this?


It seems to be a cheap solution for the problem Im about to get, once I remove the memory expansion from the ddi3 and obtain a new memory board.

[LambdaMikel]

Does the creator of this reside on this forum, or are these schematics perhaps public?

That's actually also my design (but I am not the seller of these on SellMyRetro - I have no problem with other people selling it obviously)


https://oshpark.com/shared_projects/3yA33GYO
http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/sharing-is-caring/


I still have a couple. Let me know if you want one.
I can also send you an assembled one.


I would recommend the LambdaBoard though.

[LambdaMikel]

@wietze it is in the mail now. Should arrive in ~ 10 days.

[wietze]

Awesome, looking forward!