GX4000 Multicart/SD card

[Bryce]

Not sure which posts to split, really... one, two posts maybe?

The two subjects are a bit interleaved, probably easier just to start a completely new Cart vs Disk thread with a link from this thread.

Bryce.

[TFM]

2nd that.

[Gryzor]

Tend to agree...

[Optimus]

I am curious though, if I want to do the EEPROM replace thing, how easy it is? I have no experience with electronics. But I have used soldering tool in the past. What additional tools will I need? A tube to suck the melting thing I guess? And the EEPROM base. I could start now but I am a bit scared, hehe
I bought 3 more additional Burning Rubber cartidges just for this one. My interest is for the GX4000 and to not have to buy any more the expensive games (even though I own a good collection now, not many are missing). Maybe later I will try to port Flappy UFO on the GX4000 just for my own enjoyment of running something of my own on this console


p.s. Also do I need to get a specific EEPROM with specific pins I guess?

[Bryce]

I am curious though, if I want to do the EEPROM replace thing, how easy it is? I have no experience with electronics. But I have used soldering tool in the past. What additional tools will I need? A tube to suck the melting thing I guess? And the EEPROM base. I could start now but I am a bit scared, hehe
I bought 3 more additional Burning Rubber cartidges just for this one. My interest is for the GX4000 and to not have to buy any more the expensive games (even though I own a good collection now, not many are missing). Maybe later I will try to port Flappy UFO on the GX4000 just for my own enjoyment of running something of my own on this console


p.s. Also do I need to get a specific EEPROM with specific pins I guess?

Someone like ikonsgr can probably help you out. He's in Greece too which will save you the postage. Desoldering a Cart if you've never soldered before has about an 80% chance that you damage the ACID or PCB in the process.
Most EEPROMs have the same pinout as the equivalent EPROM (except the 400Mbit ones).

Bryce.

[ArcadeTV]

Does anybody have an open cartridge at hand to provide some size measurements?

-width
-height
-thickness (presumably 1.6mm)
-location of the bottleneck (where the contacts are)
-location of the mounting hole on the pcb
-pitch of the contact-pads

thanks!

[Bryce]

Take a look at the pictures here: GX4000 cartridge - CPCWiki  The pins of the EPROM and ACID are the standard 2.54mm, you can calculate the rest from that. Or alternatively you can download and print out the Layout file of the MultiCart: Multi Cartridge - CPCWiki and measure it manually.

Bryce.

[ArcadeTV]

What can I say --- simply beautiful.
THANKS again.

[ArcadeTV]

we'll see where this is might be leading to....  ;-)

[ArcadeTV]

What's the maximum size that a gx4000 can handle?
would a 32mbit flash exceed its limits?
I'd like to drop the usb-port and concentrate on one single ic which holds all games plus the menu for selecting and bankswitching.
I have a AM29F032B on my pcb layout right now but someone pointed out that the gx4000 might eventually not be able to work with such a big thing.
Thanks!

[Bryce]

What's the maximum size that a gx4000 can handle?
would a 32mbit flash exceed its limits?
I'd like to drop the usb-port and concentrate on one single ic which holds all games plus the menu for selecting and bankswitching.
I have a AM29F032B on my pcb layout right now but someone pointed out that the gx4000 might eventually not be able to work with such a big thing.
Thanks!

Hi ArcadeTV,
    I have already designed something very similar, but I never got around to building it. I'll send you a PM with some details / notes. And yes, there are ways for the CPC to handle a Flash that size.

Bryce.

[ArcadeTV]

I will meet Bryce to work this out.
I'm very positive that this will result in something very cool 

This is all work-in-progress. I'll report any progress when the time is right.

[CraigsBar]

This looks good. Is the flash reflashable? Or is it a program once externally thing?

[ArcadeTV]

I dunno yet - we'll see what we can work out.
Personally a programm-once-thing with all games on it would be very satisfying to me...
but if the flash can be made writable - ... - who knows.
I'll let the pro's decide ;-)

[Bryce]

Just a tip for the Layout: Don't put ground-plane between the edge connector pads, it will cause havoc and possible short-circuits if the cartridge isn't perfectly aligned.

Bryce.

[ArcadeTV]

sure thing! also there are no caps yet. it's just the beginning to have something to work with. i'm already excited about it though.

[TFM]

What's the maximum size that a gx4000 can handle?

Using the commercial Cartridge design the maximum amount its 512 KB, that can be set by the right jumpers (Loetbruecken) on the Cartridge PCB.


However you can go up to 2 MB of ROM. It will be addressed in 16 KB pieces by sending a byte to port &DFxx. Values can be from 128 to 255.

[ArcadeTV]

For a warmUp I recreated the cart pcb in Eagle as it is for use with eeproms and ACID. I added the "LK" jumpers as solder-pads.
I included the gerber-files to this post.
Please download the zip, extract it and go to webGerber
Drag the files into the website and click OK on the next screen.
This should generate an interactive 3D-view of the PCB, you can play around with it using your mouse.

>>Please Note: the web-gerber-viewer has issues with the board's outlines! It will only display the rectangular shape of the pcb, of course the outlines are present and match the original pcb.

Alternatively go to Download Gerber Viewer Program and download this great piece of software. Install it, launch it,
then go to top MENU >>
FILE > Compose New > Auto
browse to the folder where you extracted my gerber-files and click
AUTO LOAD
then
OK: Read & Render

Tipp: if select VIEW > Color Preset > Net Color Haven
then you could do me a big favor and check everything. Report if you find an issue!!

Thanks and have fun!

[Bryce]

Using the commercial Cartridge design the maximum amount its 512 KB, that can be set by the right jumpers (Loetbruecken) on the Cartridge PCB.


However you can go up to 2 MB of ROM. It will be addressed in 16 KB pieces by sending a byte to port &DFxx. Values can be from 128 to 255.

There are other tricks available to allow limitless amounts of ROM / Flash on a cartridge. A 64MB cartridge wouldn't be a problem.

Bryce.

[ArcadeTV]

From what I've seen on the cart-pictures in the wiki, LK1 and LK6 seem to be pretty useless? Am I correct?

[TFM]

There are other tricks available to allow limitless amounts of ROM / Flash on a cartridge. A 64MB cartridge wouldn't be a problem.

Bryce.

Well, sounds like I have to give Maxam an intensive care this weekend, to produce at least a 64KB of something. 


The best idea would IMHO be to use a second port to select different ranges of 2 MB each. That could give up to 512 MB.     

[Bryce]

From what I've seen on the cart-pictures in the wiki, LK1 and LK6 seem to be pretty useless? Am I correct?

LK1 sets the A18 pin of the EPROM to VCC - It needs to be VCC if a 27C1001 or 27C2001 is installed. But if a 27C4001 is installed it needs to be removed and LK2 needs to be set.
LK6 connects the CPC A15 to A15 of the EPROM, this also needs to be switchable, because if a 27C256 was installed, this EPROM pin needs to be connected to VCC.
In both cases, because the EPROM pin is the PGM pin on those EPROMs.

Bryce.

[ArcadeTV]

but if you look at the blank pcb in the wiki you'll find that the traces render the jumper useless :/ or am I mistaken?

[Bryce]

but if you look at the blank pcb in the wiki you'll find that the traces render the jumper useless :/ or am I mistaken?

Yes, there are some PCB layouts where it's not permanently wired, but many are, probably because Amstrad made some great deal to bulk buy 27C1001 or 27C2001 from some supplier and realised they could save another few cents because these jumpers would always need to be set. In reality you'll also notice, that in many cases a 27C2001 is installed although the game only used 128K.

Bryce.

[ArcadeTV]

ok.. thanks!!
could you have a look at my pcb and check if i made the right connections?
(beside the 2 missing jumpers)