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Author Topic: Wanted - working Memory Expansion for CPC 464  (Read 4749 times)

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Offline LambdaMikel

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Wanted - working Memory Expansion for CPC 464
« on: 21:17, 30 September 18 »
Hi guys,

in the process of preparing a CPC 464 for sale, I also checked memory expansion with Zaxon's 4 MB, and with XMem, and again was extremely frustrated by both of these as only *1 out of 5 CPC 464s* is able to run through the Batman demo completely with them. 

I am sorry to say, but the modern memory expansions that are out there for sale don't work for the 464. They simply don't. It is unlikely that 4 out of 5 of my 464's have some defect (they are prefectly fine).

I tried dozends of different combinations - with and without DDI3 / M4 for disk, for the MX4 slot for XMem or 4 MB Piotr i tried various connections: with MotherX4, with LambdaBoard, with my Expansion Port expander that provides only one MX4 slot for the expansion, with different cable lengths, expansion ports were all cleaned with alcohol, etc.

Always, reliably, Batman Demo crashes sooner or later. I only own one CPC 464 for it run til the end (90 % chance).

This is very frustrating. Does anyone have a DKtronics 64 KB expansion for sale?

I am wondering if @revaldinho RAM expansion will be ready at some point to better that situation somehow.

Best,

Michael


Offline GUNHED

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #1 on: 02:10, 01 October 18 »
The question is if the batman demo uses RAM configurations specific to the 6128? Maybe it's not intended to run on a 464? @Rhino probably can tell us more.
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Offline Audronic

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #2 on: 04:29, 01 October 18 »
@LambdaMikel


Could you drop a copy or a link to the demo that you are using Please


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Offline LambdaMikel

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #3 on: 05:31, 01 October 18 »
The question is if the batman demo uses RAM configurations specific to the 6128? Maybe it's not intended to run on a 464? @Rhino probably can tell us more.
Well it is working on one of my 464's, and fails on the other 4.... I can post a video at some point.

Offline rpalmer

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #4 on: 15:29, 01 October 18 »
Another question is does the batman demo need a specific CRTC to work properly?

Many external memory expansions for the 464/664 will not like working with mode #3 (note it should always be correctly referenced as mode #3 since the mode if defined ONLY by the lower 3 bits).
The basic issue is that on a 6128 the address lines A14/A15 go into a PAL and the outputs from the PAL select which bank 0 or 1 is referenced along with new A14/A15 address lines to the internal RAM whereas on an external memory expansion the remapped address is now a feedback scenario with the PAL which makes impossible to know if the address was remapped or not (see attached picture). How DK'Tronics overcome this problem I do not know, some say they abused RAMDIS signal.

rpalmer

Offline GUNHED

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #5 on: 17:16, 01 October 18 »
Well it is working on one of my 464's, and fails on the other 4.... I can post a video at some point.
Yes, that's understood, so there is a difference between these CPCs. Now, it may crash every time on a CPC464, but it's not fatal on one of them. Since I don't have that computer any longer I can't test. Time to move on to 6128  ;)
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Offline GUNHED

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #6 on: 17:18, 01 October 18 »
Many external memory expansions for the 464/664 will not like working with mode #3 (note it should always be correctly referenced as mode #3 since the mode if defined ONLY by the lower 3 bits).


Actually not. Therefore it's mode &C3.
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Offline LambdaMikel

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #7 on: 19:50, 01 October 18 »
The situation is still inconclusive. First, it is extremely difficult to get the adapters or cables set up such that the RAM expansion is working. With a short cable, even a little bit of PCB miss-alignment of the edge connector, it can result in totally different results when it comes to running Batman. As if the timing is, also from an electrical point of view, *extremely* delicate.  I don't know of any expansion where the contacts need to be aligned *perfectly* in order to work. DDI3 does not have that issue. Even how the cable bends can make a difference (because it puts different stress on the edge connector??? or is it signal relection and / or cross talk between lines?)

For 4 MB Piotr expansion and DDI3, using LambdaBoard and short cable, I usually have the siutation that I power up the 464, then run "disc for Batman demo. First thing it says that I have the wrong disk for my configuration (I am using the one disk version). This, however is a false alarm - after a reset with the reset button at the DDI3, next time I start Batman, it usually loads and runs. Now that already indicates to me that there is some bug in the CPLD or the decoding logic. There is some internal state which is not properly initialized or reset or whatever.

Now, depending on the CPC 464, with perfect cable setup, Batman usually runs to the Truecolor demo part. And this is where it crashes on most 464's.

I will report the exact configurations of the 464's for which Batman Demo runs through, and also the configurations for which it crashes. Maybe that helps in tracking this issue down.

Then, with XMem, there is a second set of behaviors. It usually does not report the "wrong configuration", and currently I cannot get it to continue to load after the setup screen at all. On all 464s. And this is extremely odd, because it used to be the case that Batman demo worked better with XMem than with 4 MB from Zaxon! For unknown reasons, this situation has swapped. XMem stopped working altogether for this currently. I am wondering if this related to to the ROM contents of XMem. I will clear and re-initialize and see if that makes a difference. But why should it?

So, the inconsistent and erratic behavior of these expansions indicates to me that something is fundamentally wrong. No offense, but it shouldn't be so difficult to get the 64 KB expansion running. This is really the most important part for a 464. I don't even care that much for the rest, but the 64 KB are kind of important to work flawlessly, and with all CPC 464 models.
So, the situation is inconclusive and frustrating, and something is wrong IMHO.


I should add that I tried this with Mother X4 also, with the diode removed, such that it can power the DDI3. That gives similar results in terms of success rate as with the LambdaBoard, but slightly lower because of longer signal paths it seems.
« Last Edit: 19:54, 01 October 18 by LambdaMikel »

Offline LambdaMikel

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #8 on: 19:53, 01 October 18 »
I would suggest to design an internal 464 64 KB DKtronics RAM expansion that connects directly to the Z80 socket in order to avoid the cable issues.

That issue kind of spawned my interest in memory expansions - maybe I'll try for myself if I can make a prototype RAM expansion that sheds some light on this.
« Last Edit: 20:02, 01 October 18 by LambdaMikel »

Offline LambdaMikel

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #9 on: 20:06, 01 October 18 »
Summing up: I can't recommend any of these RAM expansions for the 464 (I can't speak for the 6128 of course, as I have not done a lot of testing there). It is simply too difficult to set them up such that they work reliably, and even if they work, their behavior is frequently erratic. Now, if this is really caused by "bat programming"  ;)  in Batman I can't say, but I also had issues with other 128 KB demos. So I believe the fault is more on the expansion side than on the demo side.  No offense whatsoever of course, just trying to be as constructive criticism as possible. But it is very frustrating for sure.  And of course, there are probably games and applications for which they work flawlessly. Maybe I am a little bit too focused on the Batman demo... I am not saying that they are not useful, but I am saying that they are not working for certain use cases / applications / demos (at least not reliably). That's all.
« Last Edit: 20:07, 01 October 18 by LambdaMikel »

Offline Rhino

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #10 on: 12:05, 02 October 18 »
The problem in the 464 with those memory expansions may be related to the #C3 mode, which is used in some effects of Batman Forever. It is possible that these expansions do not implement that memory mode correctly. I do not have them and I have not tested them, instead I have verified that 464 + DKTronics works fine.

About CRTC, BF is compatible with all types except type 2, and when it is detected, a message appears and the demo does not run.

Offline revaldinho

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #11 on: 12:57, 02 October 18 »
@LambdaMikel ,  you did ask about the state of my 464 RAM card and it's probably convenient to use this thread to talk about that, since the other thread was rather confusing given that the 6128 and 464 cards are very different things.


In my last update I had just sent off some new PCB designs to Seed. I had the boards back about a month ago and although I haven't spent much time on the cards in the meantime, I have assembled one and tested it briefly with my only 464 (an original high-key version). The good news is that it works better than my hacked proto but it's certainly not finished.


From the top of my head, the card passes all the RAM test programs I've found, it runs the DK'Tronics bank manager and silicon disk software; it runs the FutureOS GUI with the mouse pointer present and correct and no trail of debris (this being the board's main party trick of course); various games/demos all work including Hard Drivin', ChaseHQ, ZapTBall, Gryzor, Robocop, Prehistorik2 and R-Type. That's all good, as all of these games posed problems of one sort or another before I implemented the signal over-driving code. Seeing R-Type work is especially good as that did not work with my knifed and rewired proto which is otherwise very similar to the new card.


However, it's definitely not perfect. There are a few problem programs which I need to work through. I can boot to CP/M plus and run Wordstar and even edit, compile and run programs in Turbo Pascal but I get a 'Cannot load program' error on trying to run BBC BASIC. That's not right -  I was able to run BBC BASIC on the older proto when using just shadow memory, albeit with regular snow storms on screen - see the other thread.


Games-wise I only found problems with 2 games so far. Double-Dragon runs fine, but the graphics on the loading screens are garbage. Conversely P-47 has perfect loading screens but doesn't run the game at all - just a blank screen !


I would like to try Batman Forever, and particularly if it does use that mode C3, but unfortunately my 464 has the wrong type of CRTC which Batman detects and just announces 'CRTC Type 2 Not supported' before quitting.


As I said, I haven't spent a lot of time on this since the new cards came back, in fact hardly any time at all. That's partly because my attention has been diverted onto other projects and partly because I had kind of assumed that all the other RAM cards around were already pretty robust on the 464. I was surprised to read about the number of issues you raised as I was thinking that my board's only really USP was the support for the mode C3, for which there might only be a limited interest.


I will try to make a bit more time for this over the next couple of weeks. Sounds like I should get on and extract my CRTC and replace it with a socket so I can have a go at Batman Forever. I don't know if the P-47/Double Dragon issues might be CRTC related too but that would definitely let me eliminate it from my enquiries.


My latest code isn't on GitHub yet. I have a new version which supports the new DIP switches to control over-driving and shadow memory modes which should let the card be used with 6128s as well as 464/664s ... but the new code isn't fully tested on anything yet. I'll upload it once I've done some more testing and have a clear status on the different machines/modes to report even if that's not a perfect bill of health.


If you have the ability to upload new JEDEC files to the CPLD (XC9536 or XC9572) then I could build up another board and let you have one for testing with your CPC farm. Sounds like it would be very important to test with as many different 464 motherboard types as possible. I think you could say we're still in the alpha phase here and I'd like to get a bit further before opening up beta testing to many more people.


BTW if anyone in the Bristol UK area has a 464 or 2 I could borrow to test with some other motherboard types that would be very helpful indeed.


R

Offline GUNHED

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #12 on: 13:37, 02 October 18 »
Even if I don't have a CPC464 (any longer) it's wonderful that you make this great expansion eventually implementing RAM mode &C3 to the 464 - Well, a dream comes true!  ;)  So please keep your great work going!  :)
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Offline LambdaMikel

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #13 on: 19:46, 02 October 18 »
Does nobody have the schematics and PAL code of the DKtronics 64 KB mem expansion? Maybe we can learn from there how it is done "the right way"?


Now, that kind of presupposes that the Batman demo works flawlessly all of the time 100 % on all different CPC models with the right CRTCs... @Rhino you said it would work with the 464 and DKtronics, but how extensively have you tested that? Maybe that demo crashes also with the original DKtronics 64 expansion on certain CPCs?
« Last Edit: 19:47, 02 October 18 by LambdaMikel »

Offline LambdaMikel

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #14 on: 19:52, 02 October 18 »
I would like to try Batman Forever, and particularly if it does use that mode C3, but unfortunately my 464 has the wrong type of CRTC which Batman detects and just announces 'CRTC Type 2 Not supported' before quitting.

I would send you one, but the only spare 464 board I currently have also has the wrong CRTC unfortunately  >:(

If you have the ability to upload new JEDEC files to the CPLD (XC9536 or XC9572) then I could build up another board and let you have one for testing with your CPC farm. Sounds like it would be very important to test with as many different 464 motherboard types as possible. I think you could say we're still in the alpha phase here and I'd like to get a bit further before opening up beta testing to many more people.


I am able to flash these CPLDs as I am using them for my own work. More than happy to help with my "464 farm"! Let me know  :) 

Offline revaldinho

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #15 on: 23:59, 02 October 18 »
@LambdaMikel - OK I'll take you up on that. If I build and ship you a board at the weekend you can try it out on your 464's and I'll hold off on extracting my own CPC464's CRTC 'til you've had a go. Probably not the best idea for me to risk damage to my only 464 at this point. I'll PM you.




Offline tjjq44

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #16 on: 11:19, 03 October 18 »
Hi,

I've been looking for an expansion memory to fit my 464 for a long time! Being "fully dk'tronics compatible" is an absolute need for me since I want to be able to run actual and old 128k software and demos.

I could buy a used 64k or 256k dk'tronics expansion but currently they are very rare and when one comes on sale, its price is outrageous, more than a new one back in 1985, even more expensive than an actual used cpc 664!!!! Apple 1 excepted, it's the first time I see a used electronic product exceed the price when it was launched  :o !?!?!?!

@revaldinho: Hope you will succeed in making this dream come true! When you'll get it finalized, I'll be interested to buy one (I can solder components by myself but sourcing them may be a little bit complicated where I live in France) and test it thoroughly on my 464s (I own 3 of them) and maybe if I'm confident enough on my 664* ;-) I also have a UM6845R (crtc 1) spare chip I can send to you if you need.


*This 664 was in fact my cousin's one when he was young. He used it from 1985 to 1991 or so. And I used it a lot when I was on vacation at my aunt's in the mid 90's. When she moved in the late 90's, she asked my cousin what to do of his old computer, he answered: ask Thomas, he might be interested... Yes I am !!!  :D  
« Last Edit: 11:38, 03 October 18 by tjjq44 »

Offline GUNHED

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #17 on: 16:21, 03 October 18 »
Wouldn't it be better so day 'Amstrad Compatible', which means to be compatible to the way the 6128 does manage his expansion RAM? I would say yes, because we should at first stay compatible to the producer of the CPC. The dk'tronics for the CPC464 can not (as far as I know) provide RAM mode &C3 in the same way the CPC6128 does.  :)
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Offline tjjq44

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #18 on: 18:59, 03 October 18 »
The dk'tronics for the CPC464 can not (as far as I know) provide RAM mode &C3 in the same way the CPC6128 does.  :)


I know that! And no 464 memory expansion will do. The only way to afford it is to modify the 464 logicboard what I refuse!


dk'tronics is still today the most compatible cpc 464 expansion but costly, hope revaldinho will succeed in his project

Offline tjjq44

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #19 on: 11:38, 04 October 18 »
After digging the web for a few days, I found that:

https://www.sellmyretro.com/offer/details/ram-expansion-512-kb-for-amstrad-464~~6128-29065

The site says "DKTronic compatibile", I have some doubts concerning the 464 but I let me go for an order, £30 isn't a so big deal!

Never seen this expansion elsewhere, don't know if it is based on some project already known on the web... I'll test it and feedback my opinions ;-)

Offline tjjq44

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #20 on: 13:10, 04 October 18 »
Never seen this expansion elsewhere


In fact it is Zaxon's 512k memory expansion, seems LambdaMikel had problems with his 4MB one, hope this one will be more 464 compliant ;-)
« Last Edit: 13:12, 04 October 18 by tjjq44 »

Offline LambdaMikel

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #21 on: 16:46, 04 October 18 »
After digging the web for a few days, I found that:

https://www.sellmyretro.com/offer/details/ram-expansion-512-kb-for-amstrad-464~~6128-29065

The site says "DKTronic compatibile", I have some doubts concerning the 464 but I let me go for an order, £30 isn't a so big deal!

Never seen this expansion elsewhere, don't know if it is based on some project already known on the web... I'll test it and feedback my opinions ;-)
Well, I had that expanion before i went for Piotr's / Zaxon 4 MB expansion, which is being discussed here... I traded it in for the 4 MB one. AFAIK, the switch on the 4 MB mem expansion that we are discussing here if for DKtronics mode on / off.

In my experience, the 512 KB expansion suffers from exactly the same problems as the 4 MB version from the same developers.
« Last Edit: 16:50, 04 October 18 by LambdaMikel »

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #22 on: 16:52, 04 October 18 »
I have one of Piotr's expansions, I bought it a couple of weeks ago. There is a switch on the top for 464/6128 operation so bear that in mind. The RAM check passed when I tested it on my 464 but I haven't tried BATMAN.
I Can only use my M4 as I don't have a DDI3 anymore - so I'll give it a go.. If anyone want's me to test something with my 464 just ask.
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Offline LambdaMikel

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #23 on: 17:01, 04 October 18 »

In fact it is Zaxon's 512k memory expansion, seems LambdaMikel had problems with his 4MB one, hope this one will be more 464 compliant ;-)
Well, give it a try - in my experience, it works on some CPC 464's, and fails on others. As I said, I had it before and turned it in when he came out with the 4 MB version. And more memory wasn't the only reason for turning it in  :) I also exchanged the 4 MB version once, and the second one I currently have is doing a lot better than the first one, but there are still issues with it which are being discussed in this thread.

For reference, here was some previous discussion, including the pictures and stats of the 464's on which I had tested:
http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/4mb-externial-ram-expansion-will-be-soon/100/
« Last Edit: 17:10, 04 October 18 by LambdaMikel »

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Re: Wanted - working Memory Expansion for CPC 464
« Reply #24 on: 17:13, 04 October 18 »
Well, give it a try - in my experience, it works on some CPC 464's, and fails on others. As I said, I had it before and turned it in when he came out with the 4 MB version. And more memory wasn't the only reason for turning it in  :) I also exchanged the 4 MB version once, and the second one I currently have is doing a lot better than the first one, but there are still issues with it which are being discussed in this thread.

For reference, here was some previous discussion, including the pictures and stats of the 464's on which I had tested:
http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/4mb-externial-ram-expansion-will-be-soon/100/
Yeah I remember reading that at the time. I thought he pulled them off sale because of the problems ???
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