36-way edge connectors and ACID-less cartridge

[arnoldemu]

I will be ordering some 36-way edge connectors. The type suitable for plugging cartridges into.

Is there any interest for more? Maybe we could pool together and buy a bigger batch?

[fano]

Maybe Eliot would be interested for the CPC parts online shop : http://amstradcpc.info/parts/about.php

[redbox]

I will be ordering some 36-way edge connectors. The type suitable for plugging cartridges into.

What are you planning on doing with them?

I'd like to make an extension cable so my cartridges can sit outside of the Plus.

[Bryce]

One of the plans for them is a new cartridge replacement / ACID solution, that I cooked up with Arnoldemu over the last few days. More details when I've built one.

Bryce.

[steve]

You could build a cartridge port for CPC's to attach to the expansion port.

[fano]

One of the plans for them is a new cartridge replacement / ACID solution, that I cooked up with Arnoldemu over the last few days. More details when I've built one.

That sounds very interesting , keep up the good work !

[redbox]

That sounds very interesting , keep up the good work !

Yes, it's great that Bryce got a Plus with all this exciting Plus hardware being developed 

[Bryce]

Having recently discovered how difficult it is to source the 36way socket, I went on a search for alternative solutions. Luckily the connector was used widespread for a much more common application The second half of a 16bit ISA socket has the exact dimensions of 36way socket used on the cartridge port. For those who've forgotten / are too young / weren't ever aware, 16Bit ISA is the long black extension socket common on most PC Motherboards back then, before PCI replaced everything. There were 2 to 5 sockets on most old PC Motherboards. I've got my hands on one with 5 sockets and will remove them when I have time. I have a few cool ideas for them

If you happen to have one of these Motherboards lying about, don't scrap it just yet, or at least not without salvaging the sockets first.

Bryce.

[OCT]

Please don't. Legacy PCs have got feelings (of fear and pain) too unless you promise to only pry the ports from their cold dead hands erm circuit boards when all hope is gone for them to ever run Second Reality again...

[awergh]

Yes those poor legacy PC do indeed have feelings. Dead boards are fine though which many have ISA upto Socket 370 (Pentium III) boards I believe though not all do mostly only ATX boards and not microATX. Another place is if you have old OEM PCs (dead of course) there was an adapter card thing which would slot into an isa slot on the board and give you three ISA slots sideways. This is what OEMs seemed to do to fit the expansion cards into a smaller space I think.  I have 2 which have no use at all that I can think of.

[Gryzor]

Nah - PCs are crap, only as good as the software that runs on them... I say go on and slaughter them!

[Bryce]

Well for a start, there were so many of these made, they're not going to be rare any time soon, although I do agree with Awergh, "Riser boards" would also be a good source, but I can't remember seeing 16bit ISA versions of these.

As far as having any attachment, sentiment for these parts, I'm with Gryzor: Amstrad / Atari / Commodore etc are retro, but a Pentium / AMD / Cyrix from the 90's is just an annoyingly slow version of what I use today.

Bryce.

[arnoldemu]

Well for a start, there were so many of these made, they're not going to be rare any time soon, although I do agree with Awergh, "Riser boards" would also be a good source, but I can't remember seeing 16bit ISA versions of these.

As far as having any attachment, sentiment for these parts, I'm with Gryzor: Amstrad / Atari / Commodore etc are retro, but a Pentium / AMD / Cyrix from the 90's is just an annoyingly slow version of what I use today.

Bryce.

I don't have any feelings for PC too. In fact the day after Bryce told me he could source these parts I had just taken a P2-333 to the local recycling centre.


I have looked in the UK and asked a few suppliers the only source I can find is rapidonline.com that are cheap but  can't supply until April.
Other sources have been far to expensive.

[awergh]

I know they aren't rare but that doesn't mean I'm not attached to them, think I only have 2 dead motherboards with ISA slots not that I checked but I'm pretty sure I do.
I also definitely have 2 riser boards with 3 16bit ISA slots. Some riser boards have PCI and ISA I believe but I don't have any spare ones of those.

[steve]

Do you keep your old cookers and fridges?, the PC is an appliance, throw the thing away.

[awergh]

No PCs are not an appliance to me, You can't just run everything on the same piece of hardware and only having one isn't right at all.

[Bryce]

Don't get all upset about it, the Motherboard is a very old Socket 3 PCB, where the Cache, the BIOS and several other parts were already removed for other projects. There's also a good PALCE 16V8H there which I will definitely use and the RAM sockets might also be salvaged, so it's not being thrown away, it's "donating it's organs"

Either way, I did my "Is it worth keeping test" and it failed: It couldn't run Crysis. So at least it gets to enhance another vintage computer.

Bryce.

[Bryce]

So I said I had a few ideas for the 36way connector and tonight I built and tested the first one. For obvious reasons (ie: I couldn't think of anything better) I call it the "Man In The Middle" cartridge.
The general thinking was: If I want to write and distribute cartridge games/utilities cheaply, then why should I try to source and sell an ACID to someone who already owns one? The MITM cartridge gets around this problem, but needs an original cartridge so that it can "borrow" the ACID from the original. To do this it has the normal edge-connection and an EPROM/Flash socket, but instead of an ACID it has a socket to connect an original cartridge. The connector forwards the signals that the ACID needs, but not the EPROM signals, so the original EPROM is effectively disabled. To do this, no changes are required to the original cartridge. The PCB is tiny (29mm) because I wanted the original cartridge to be locked in the CPC using the second notch in the cart-case. The design is made for 512K EPROMs only, but I did add a jumper to allow both UV and Flash EPROMs to be used, the resistors (2 are needed) are hidden under the EPROM.

Bryce.

Here's some pics of the prototype:

[robcfg]

Terrific!


It reminds me of the SNES adapter to play japanese games. It had two slots, one for the japanese game and the other for a european one so it could do the region verification on it and allow the japanese game to be played.


I find that it is also a great idea because that way you don't have to break an original cartridge.


Great work, Mister!


P.S. If you decide to make some of them, I'd be very interested. 

[Bryce]

There's no plans to make any more of these, due to a lack of 36way connectors (although they are probably easier and cheaper to find than an ACID). The one connector I had was from the ISA of an old motherboard as mentioned above, but removing a 36 pin device from an 8 layer FR4 PCB proved to be  an absolute pain in the arse, that took me almost 2 hours, I won't be doing that a second time. The one in the picture is promised to Arnoldemu, as the original idea was born from discussions with him about alternative cartridge solutions.

Bryce.

[arnoldemu]

There's no plans to make any more of these, due to a lack of 36way connectors (although they are probably easier and cheaper to find than an ACID). The one connector I had was from the ISA of an old motherboard as mentioned above, but removing a 36 pin device from an 8 layer FR4 PCB proved to be  an absolute pain in the arse, that took me almost 2 hours, I won't be doing that a second time. The one in the picture is promised to Arnoldemu, as the original idea was born from discussions with him about alternative cartridge solutions.

Bryce.

Excellent! Thanks.
I am really happy this worked!

[Bryce]

Hi all,
     I created an initial page for the "Man In the Middle" Cartridge here: http://www.cpcwiki.eu/index.php/MITM
I'll add layout files and schematics later, for those of you who want to build one. I also had to make slight changes to the prototype due to practical usage issues:
Because of the small size of the PCB, it goes completely inside the CPC and was very difficult to extract, so I added a wire loop to make it easier to remove. I also had to shorten the jumper to be below the height of the EPROM, because it kept catching inside the CPC (this doesn't happen on the other cartridges I've made because the cartridge housing protects the jumper). Instead of the loop, I could have just made the PCB big enough so that it protrudes, but that would have meant that the cartridge would be unstable / hang down and could also be removed without turning off the CPC (not a good idea), it's also cheaper if the PCB is smaller.

Bryce.

[norecess]

Seems very great Bryce !


Does it mean in the end you could put 32 ROMs (16*16Kb) on it?


And then... do you think (in theory) it could be possible to replace the ROMs by a RAMCARD-based solution ? so in the end, that would be programmable directly from the REAL CPC ? (or any PC-based solution)

[Bryce]

Whoa, slow down norecess, firstly, why would you want 16x 16K EPROMs on a board, when it already has 512K in one much cheaper EPROM? It's possible, but completely pointless (and very big).
A RAMCARD of any sort on the cartridge socket is difficult (note that I don't say impossible) due to the WR signal not going to the port. As far as writeable ROMs are concerned, the MegaFlash will solve this and also work on both the standard CPC and the Plus.

Bryce.

[norecess]

Where can I buy one?








Nah... kidding. Still, that's a great experimentation you did there.


What will be your everyday's use with it?