Cirtech Sprinter

[mdc]

Just picked up a PCW8256 (haven't unpacked it yet), and I've been doing some reading and heard about the Cirtech Sprinter, essentially an 8Mhz Z80 module with 128kb of SRAM onboard, along with up to 2MB of DRAM.


Has anyone ever seen one of these boards, and/or have a circuit diagram for one? I'm guessing that the chances of finding a reasonably priced module are slim to none, so actually building one from scratch may be more achievable.

[GUNHED]

Yes, it's a shim for the CPU of the PcW, I got one somewhere, but all the data should be in the net. I don't remember if it was from Cirrtech though.

[JonB]

Would be interesting to reverse engineer it... and produce a clone.

[mdc]

That's the idea! I've found a couple of low-resolution photos online from trade magazines circa 1986, but unfortunately none of the chips markings are readable, and definitely not the traces.


For what it's worth, it didn't look like there were any custom chips used, which leads me to believe it's all done using discrete logic, so a clone should be doable.

[JonB]

Well, if CPC664 would like to dig his one out and post some pictures of the board, we might make a start...?

[JohnElliott]

Any use?

[JonB]

Thanks John!


Those pictures tell me that it cannot be reverse engineered using pictures alone. 


I assume it plugs into the Z80 socket via the two rows of pins on the underside, like a shim. I'll take a closer look later on. I see a bunch of RAM on there,too.

[robcfg]

Hi John, welcome to the CPCWiki!


Scans are always welcome, as they give us the chance to study the board without having it.


Do you mind if I use your pictures for the PCWWiki? Some friends and I set it up as we saw there were lots of PCW stuff that wasn't preserved nor documented.


If you'd like to take a look, this is the address: http://habisoft.com/pcwwiki


Most info is still only in spanish, but we're translating the content when there's some free time.


Cheers,
Rob

[JohnElliott]

I assume it plugs into the Z80 socket via the two rows of pins on the underside, like a shim.

Correct, and the two flying leads are connected to (IIRC) the MDIS and 32MHz lines on the motherboard.

[JohnElliott]

Do you mind if I use your pictures for the PCWWiki? Some friends and I set it up as we saw there were lots of PCW stuff that wasn't preserved nor documented.

By all means.

[Bryce]

That's almost a complete computer on there. Reverse engineering would require component removal and reverse engineering of the PAL at the top.

Bryce.

[JohnElliott]

And of course having done this, I now find it's already been done.


(If the link doesn't show: Google 'sprinter pcw MDIS' )

[jamesots]

That's almost a complete computer on there. Reverse engineering would require component removal and reverse engineering of the PAL at the top.

I saw a good description of how the Sprinter works somewhere on the internet in the last few weeks, but unfortunately I can't find it again. I remember it talked about shadowing the PCW's RAM, and having to do something clever so that the GA could still read video memory at the right speed. I don't think it would be an insurmountable task to make a Sprinter using a CPLD, but I'm personally more tempted to make a whole PCW on an FPGA.

[JonB]

Correct, and the two flying leads are connected to (IIRC) the MDIS and 32MHz lines on the motherboard.

Judging by their positions on the row of holes I would suggest that the holes comprise a pad for connection to the expansion port of the machine. Only a guess, mind you...

[JonB]

That's almost a complete computer on there. Reverse engineering would require component removal and reverse engineering of the PAL at the top.

Bryce.

I was going to say "it's a computer" or some such but as I'd only glanced at the board I wasn't 100% sure. PALs... not easy to reverse engineer if the security fuse is popped.


I have the same problem with the diagnostic card...