ACID : what a cartridge game or application may add ?

[MacDeath]

Not a novelty, ROM programs already existed for applications.

Yet Amstrad PLUS cartridges are still interesting.

It freed the Extension port in case of unmodified configuration (Many modern ROM/RAM boxes feature extra stuff)

So what are the coders thinking about with the perhaps soon to come Cartridges solutions ?

The main advantage is that Cartridges oriented Programms are obviously GX4000/PLUS oriented.

No stuff like Prehistorik 2 with its Disk including both CPCold and PLUS versions then.

Also, this may need new way to conceive programms.

Games :
having 256Ko or 512Ko will enable graphically heavy games in PLUS (HardSprites, lots of graphics and sounds perhaps).

Despite games may not be that bigger (Gameplay wise), old games often used soft applications to reverse sprites or tiles (R-Type, Rick dangerous) in order to save RAM space and reduce the loading in 464 configuration.

Though saving RAM/DATAs space, this also was a bit heavier on the Z80 as Softwared routines.

Also the almost lack of loading time and alsmot direct Access to all Datas rapidly, more complex looking stuff may be achieved, or perhaps better use of Sampled sounds ?

Compression of Data :

This may still be used for Big overscan Cinematic/Intro pages. Why waste that many space in such stuff...

But concerning In-Game datas, this may not be that needed that much, as 512ko is more than enough to get an advanced enough game.

Rick dangerous used such compression of datas.
but this may use Soft-ressources, so CPU ressources.

A problem may occur with "Save Game" possibilities.
Yet old school action/arcade games may not really need this, and RPG-like games are more Computer oriented anyway.


Applications :

What would you plan for those ?

Extra RAM :
Despite a notable Gain, the ROM is read only.
Having more RAM is still better, perhaps even more with applications.
While upgrading an 464+ is not that difficult, on a GX4000 it's getting trickier.

No proper Extension port, nor free slots on motherboard.
Of course Applications are perhaps less possible on this as no Keyboards nor DATA-saving facilities.

Would 64Ko be enough then ?
A game like Rick dangerous could prove that 64Ko is quite enough for a complete game indeed.

And many 128 Ko RAM games only featured extra Sounds.

New products or Modings ?
Quite a dilemma.
Getting old games/applications simply slightly modded and put on Cart is concievable.

But developping entire new stuff would of course be better, yet longer and harder.

Also oldd stuff would perhaps not be that well optimised for the Cartridges extrafastloading capabilities.


Discuss.

[fano]

For games , it is simple : 512K ROM = bigger , faster , nicer and potentially better 

It is time to show the real power of GX4000/464 & 6128+ 
I just hope we'll get new games especially designed for cartrige or highly improved versions (Star Sabre PlusPlus anyone ?) , not just compilations of existing games.That would be a shame to see that potential unused.
For me , as i already say , i'll try to use that potential
That will obiviously change the way i am working.I think i'll need a new utility to build cartrige file easily.

[jbaudrand]

:/ any news about cartridge homebrew? is it possible? is there constraint in programm structure or is it exactly like a big floppy disc?

[steve]

I think the problem is the ACID chip, and getting the cartridges manufactured.

There was a thread that told of a supplier who had 500 genuine ACID chips in stock, but no-one seems to have bought them, at least if they have they are keeping quiet about it.
If ACID chips are not available then they must be cloned, apparently the secrets of the ACID chip have been cracked by a Spanish group but I don't know where any details about this are to be found, hopefully it will go in CPCWIKI eventually.
Finally you want someone to produce a run of cartridge casings, some people in Poland are changing the ROMs in genuine Amstrad cartridges, but that is not a viable long term solution.

[arnoldemu]

I think the problem is the ACID chip, and getting the cartridges manufactured.

There was a thread that told of a supplier who had 500 genuine ACID chips in stock, but no-one seems to have bought them, at least if they have they are keeping quiet about it.
If ACID chips are not available then they must be cloned, apparently the secrets of the ACID chip have been cracked by a Spanish group but I don't know where any details about this are to be found, hopefully it will go in CPCWIKI eventually.
Finally you want someone to produce a run of cartridge casings, some people in Poland are changing the ROMs in genuine Amstrad cartridges, but that is not a viable long term solution.

The functionality of the ACID has been broken. The Spanish guys did some investigation and uncovered some details but they didn't finally find it's functionality. In fact it was nocash (on this forum) who discovered how it works. All the info is already on the wiki

The problem now is to create acid ics easily and cheaply, casses and pcbs for the acid and rom to be on. Then games created for cart can be distributed.

I believe you are correct that Polish bootleggers were taking existing carts, programming a new eprom and putting it onto the board.

As far as developing for cartridges:

Well you can do this already if you use winape or arnold emulators. Both of these emulate cpc+ and cartridges.

You can use buildcpr to create a cpr file from a binary file. But then it's up to you to generate that binary file at the moment because the tools are not done for this. (www.cpctech.org.uk for buildcpr)

Creating a game for cartridge is quite different than creating a game for disc.
Code can't be self modifying if it is executed direct from ROM. You can use the ROM to store both program and data, so not necessarily to load all the code into RAM at one time. Accessing the ROM is done in 16k pages, which you must execute a Z80 I/O instruction to make this readable in the Z80's address space.

So if you want to write a cart please go ahead and share any development problems if you find them, and then this will help others to write cart programs too. The issues generally you will hit will be down to the exactness of the emulation. Some of this you can do by testing on a real cpc+ with a tape/disc version.

But finally you would need to test a real cart on a real cpc+ and gx4000 before releasing it, because you may find changes that need to be made to make it work correctly on real hardware.

[jbaudrand]

thanks for explanation, so if I understand correctly, I could store variable in RAM for quest/game progress/score and access to ROM for loading different level or totally new kind of game. My actual skill didn't allow me to understand the 16k ROM access with Z80.

I have only a simple 6128, so I will stay on disc for my little game.

for making real cartridge, the team from Atari Age or nintendo age can build  cartridge from scratch, and I've seen on the web a guy who made James Bond Lego from scratch, so I believe there's a affordable tool that exist for creating plastic case but I don't know where to ask for.

for Acid chip: is it just a common eprom or not?

[TFM]

There was a thread that told of a supplier who had 500 genuine ACID chips in stock, but no-one seems to have bought them, at least if they have they are keeping quiet about it.

I tried to buy them! This nice company didn't answer me. 

[arnoldemu]

thanks for explanation, so if I understand correctly, I could store variable in RAM for quest/game progress/score and access to ROM for loading different level or totally new kind of game. My actual skill didn't allow me to understand the 16k ROM access with Z80.

yes correct.

The Amstrad cartridge is a simple EPROM with ACID custom protection chip. There is no way to store your progress for starting again another day unless you save the progress to disc, cassette, or present the user with a code they can enter to continue.
There is no eeprom or memory backup on the cartridge.

Other people are looking into how this may be possible with some sacrifice to the total available ROM.

Well maximum rom size is 512K, but nobody has used this yet. It is technically possible, but I don't think any existing games use it.
Accessing the ROM.

When the CPC+ is reset, rom page 0 is visible in z80 ram between &0000-&3fff. You can also enable another page in the memory range &c000-&ffff. Writing to these ranges while the rom is paged in, writes to the ram area underneath. When running code you can use the standard I/O to select and enable/disable the rom.

I have only a simple 6128, so I will stay on disc for my little game.

cool. I will be interested to see this when it's done.

  for making real cartridge, the team from Atari Age or nintendo age can build  cartridge from scratch, and I've seen on the web a guy who made James Bond Lego from scratch, so I believe there's a affordable tool that exist for creating plastic case but I don't know where to ask for.

for Acid chip: is it just a common eprom or not?

No, it's a custom chip, effectively a kind of random generator. The value it generates must match the value that the ASIC (custom chip inside CPC+) generates. If it doesn't the game will not work. The ROM itself is not protected (e.g. the opcodes are not encrypted).

So, after TFM news, it seems the only ways are to change an existing cart, or have new ACIDs made. I believe Octoate has already made the VHDL for it. MacDeath is also working on making an ACID + other extras.

So what can it add?

Well all code and data can be in ROM. Then the RAM can be used for variables and for screen.
As far as I know, there is no difference from executing from ram or rom, in terms of read cycles. I think the same number of cycles happen for rom and for ram.

EDIT: So what can we do now? Well we can write the cartridge program using an emulator. So we can start to gain the knowledge of how to make rom based programs and then see what extras it can give us.

[TFM]

Universe has a funny timeing. Got an email today, they offered me the ACID for 7,86 Euro each (if I take 100). Keep you informed...

[jbaudrand]

TFM/FS: they still build them? or is it an old stock?

[arnoldemu]

Universe has a funny timeing. Got an email today, they offered me the ACID for 7,86 Euro each (if I take 100). Keep you informed...

beware of fake ics. There are some fake SIDs going around, and some of them are not even close to being real sids.

If these are genuine then if I could use it to test my own cartridge games then I would have one.

[TFM]

TFM/FS: they still build them? or is it an old stock?

Yes, it's from 1992.

beware of fake ics. There are some fake SIDs going around, and some of them are not even close to being real sids.
If these are genuine then if I could use it to test my own cartridge games then I would have one.

Well, for c64 all you get is a fake ;-) Because it's no CPC.

However I got a lightly better price now (it still hurts, but what can you do), it's 6,85 Euros for a piece if you take 100. So I ordered 100. May they rip me off or send me fake IC's - can happen, then I'll take my consequences    But I hope everything will work out well.

[Trebmint]

Yes, it's from 1992.
 
Well, for c64 all you get is a fake ;-) Because it's no CPC.

However I got a lightly better price now (it still hurts, but what can you do), it's 6,85 Euros for a piece if you take 100. So I ordered 100. May they rip me off or send me fake IC's - can happen, then I'll take my consequences    But I hope everything will work out well.

Can I just say congrats TFM/MS for reaching 464 posts. Hoep you reach 6128 in the not to distant future

[TFM]

Hehe, thanks a lot! I hope that I reach one day 6128+ posts :-)))

Now I payd the ACIDs, including the wonderful german 19% tax and shipping the unit is now 8,21 Euro. I will probably not go to a bar this year, this way I get the money back. And it's better for health and CPC. My next step it to get cartridge plastic covers and circuit boards, any ideas?

[steve]

Could you offer an extended cartridge that has an exposed ZIF socket so we could easily and quickly change the 512KB rom and reduce the need for one ACID chip for each ROM.

[arnoldemu]

Could you offer an extended cartridge that has an exposed ZIF socket so we could easily and quickly change the 512KB rom and reduce the need for one ACID chip for each ROM.

For me I would like some way to be able to reprogram the cartridge, so having flash or static ram on it and an easy way to download data onto it. This would be the best, because then I could easily test my programs are working.
I don't have eproms or tools to write them.

[TFM]

Don't know what you mean with a ZIP socket, is it like a Textool socket?

However I was indeed thinking about such things.

But like mentioned before, the ACID is one component, the remaining parts of the cardridge are still missing.

The biggest problem is to get the plastig cover. Does anybody know where we can get them?

[TFM]

For me I would like some way to be able to reprogram the cartridge, so having flash or static ram on it and an easy way to download data onto it. This would be the best, because then I could easily test my programs are working.
I don't have eproms or tools to write them.

You should indeed contact Dr.Zed about this ...

[jbaudrand]

I've made a few search to make custom cartridge.. but don't know how to find it in europe... http://www.injectionmolder.net/

[TFM]

$1500 makes no sense :-(

But if somebody would already have one...

[Gryzor]

You bought them???!!! I think we should have all pooled some money to get them... unless you're planning to use them and sell some sort of product in the future, which is of course very much OK.

[andycadley]

One possibility might be to get them done through one of those online 3D printing places like http://www.shapeways.com/ though I've no idea whether the end result will be sturdy enough (and obviously somebody needs to 3D model one first).

It'd be cool if we could get these made, it has to be better than what I'm currently doing which is basically butchering older, less desirable, GX cartridges. Although that project has stalled somewhat as I can't get my old eprom blower working on modern hardware, so have had to order a shiny new USB one!

[arnoldemu]

Don't know what you mean with a ZIP socket, is it like a Textool socket?

However I was indeed thinking about such things.

But like mentioned before, the ACID is one component, the remaining parts of the cardridge are still missing.

The biggest problem is to get the plastig cover. Does anybody know where we can get them?

Are there any cases or even plastic boxes of a similar dimension that could be modified to suit as a temporary alternative?

Maplin sell plastic boxes. I know it's not a perfect copy, and it would need a section cutting out of it, but could it work as a cheap alternative provided it didn't fall apart?

Markus measured the box for me (cm):

7 x 6.5 x 1.5

[TFM]

You bought them???!!! I think we should have all pooled some money to get them... unless you're planning to use them and sell some sort of product in the future, which is of course very much OK.

Well, I have indeed planned to use them for a certain project. Pooling would be nice, but not for me, since I live in USA and I don't like somebody sending hardware to me here. They already stole my X-Mas cookies - my former girl-friend was pretty disappointed!
So I have to "use" my ACIDs next summer in less than two weeks, in case I got circuit boards and covers... However I can't access them before. And sending them to USA is like spending them to some sort of .... whatever (I think they read my posts here...!).

But n-tronics still has 400 in stock, so get them.

We had the pool-order discussion a couple of months ago, and nobody really told that he/she will definitely buy one. So I don't know if somebody wants one - except Arnoldemu.

[steve]

I will hazard a guess that you plan to sell cartridges with Futureos in them, any chance that you would sell cartridges with no rom in them?