Author Topic: PCW Expansion Board  (Read 529 times)

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Offline Charlie

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PCW Expansion Board
« on: 19:21, 18 September 19 »

Hello all,
It's been an absolute age since I showed my face round here - sorry about that.I've had a few projects on the boil but sadly can't afford to actually make / test them so I thought I'd post them all here in case anyone wants to run with any of them.

#4) PCW Expansion BoardI happen to have a PCW 8256 keyboard and motherboard kicking around and wondered if the latter could be crammed in to the former. With a bit of fenagling the answer seems to be "yes". With the addition of a reprogrammed Gotek and a butchered Keyboard Mouse I'm well on the way to a nice little CP/M box.
Of course there's other stuff I'd like to give the job some class so apart from the Z80 Accelerator I posted in the CPC Hardware forum I've also done an expansion board for the PCW:
-Composite circuitry for an external monitor
-uIDE compatible IDE (that took a bit of reverse engineering based on the published I/O scheme)
-DK'tronics Sound and Joystick functionality
-I do have a version with Digiblaster compatibility that I'll probably post eventually for anyone is interested in soldering lots of resistors

Hello all,
It's been an absolute age since I showed my face round here - sorry about that.I've had a few projects on the boil but sadly can't afford to actually make / test them so I thought I'd post them all here in case anyone wants to run with any of them.

#4) PCW Expansion BoardI happen to have a PCW 8256 keyboard and motherboard kicking around and wondered if the latter could be crammed in to the former. With a bit of fenagling the answer seems to be "yes". With the addition of a reprogrammed Gotek and a butchered Keyboard Mouse I'm well on the way to a nice little CP/M box.
Of course there's other stuff I'd like to give the job some class so apart from the Z80 Accelerator I posted in the CPC Hardware forum I've also done an expansion board for the PCW:
-Composite circuitry for an external monitor
-uIDE compatible IDE (that took a bit of reverse engineering based on the published I/O scheme)
-DK'tronics Sound and Joystick functionality
-I do have a version with Digiblaster compatibility that I'll probably post eventually for anyone is interested in soldering lots of resistors

-The design is quite modular so feel free to make use of the parts you actually want

I was going to add lots of other stuff but the board would be too big to fit! The board is intended to be soldered to the pads behind the expansion connector but throw on a female connector and it should work as an external upgrade for any (non-16) PCW. With that in mind I've also done a case for 3D Printing - the File is in Autodesk 123D format. The case is designed for the Dk'tronics Parallel RAM board but should be easy enough to alter for whatever. (Mock up of the 8256 motherboard also included)

Quite untested so use at your discretion.

I was going to add lots of other stuff but the board would be too big to fit! The board is intended to be soldered to the pads behind the expansion connector but throw on a female connector and it should work as an external upgrade for any (non-16) PCW. With that in mind I've also done a case for 3D Printing - the File is in Autodesk 123D format. The case is designed for the Dk'tronics Parallel RAM board but should be easy enough to alter for whatever. (Mock up of the 8256 motherboard also included)

Quite untested so use at your discretion.

All the best,
Charlie.
« Last Edit: 19:43, 18 September 19 by Charlie »
Charlie.

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Offline Charlie

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Re: PCW Expansion Board
« Reply #1 on: 19:26, 18 September 19 »
oops error
Charlie.

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Offline JonB

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Re: PCW Expansion Board
« Reply #2 on: 11:13, 19 September 19 »
Good show Charlie

Correct me if I'm wrong, but the pitch of the pads behind the PCW expansion connector is non standard, so .2" pitched headers as used on your board layout won't fit. I had the same problem when I designed uIDE. I recall cursing whoever did the PCW board layout...  :D

You may have the same problem with the 74LS02 that I did - will probably need 74F02 as the timing seems to be quite tight.

The IDE activity light will be on all the time, until there is activity (at which point it goes off). On uIDE I chose to invert this (which lead to additional componentry - I might have dropped the PWR light and just had a reverse activity light like yours (would've made it easier to build and who would have complained?)
« Last Edit: 11:20, 19 September 19 by JonB »

Offline Charlie

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Re: PCW Expansion Board
« Reply #3 on: 18:19, 22 September 19 »
Hi JonB,
You may well be right on the connector pitch, I'll keep that in mind for any updates - thanks. :-)

FWIW: This design was inspired by my having an 8512 motherboard and 8256 keyboard kicking about. With a bit of fiddling one does fit in to the other but there's not a lot of room. With that in mind I wanted a multi-function upgrade that could fit within the reaming space. All the 'modules' are independent so if anyone wanted to use an individual section that should be workable.
Of course if anyone wanted just the IDE part of 'my' interface they would be much better off talking to your good self about getting a proper board.

On the IDE front I'm not a great coder so if I wanted an IDE solution for 'my' board I'd need to point my plans at an existing driver. For the PCW that meant making something that would function with your uIDE code so I'm not surprised to have come up with something very similar to your design...
...while I have the opportunity I just want to say how much I appreciate the hard work you have put in to your uIDE interface and support software.

PS
While I think I've just enough components to make a veroboard prototype, so there may be further news, this layout is wholly untested. So if anyone feels like having a go PLEASE be sure you are happy in your own mind that the design works!
Charlie.

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Offline JonB

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Re: PCW Expansion Board
« Reply #4 on: 19:56, 23 September 19 »
I had a great deal of fun writing those drivers. And help from John Elliot...

I think what I might have a go at is the DK'Tronics thingie. Although, I believe there is a schematic for it somewhere. At the moment I an trying to finish the RTC software (it's elusive).

My designs are generic, so not PCW specific apart from the expansion port adapters. I have a uIDE running on my Superbrain, for example. It's just a matter of adding some jumpers so that the I/O address can be altered to suit the target machine, and using the Z80 pinout via a shim to give a bus to connect it with. PCW specific stuff like the RAM board can't be made generic because I imagine it uses some of the PCW's extra lines that are not on the Z80 bus (guessing here, I haven't looked too closely at the design). Certainly, the uIDE auto boot card I am planning will need at least MDIS. But that is a way in the future...

Regarding prototypes, I did build one for the uIDE (it used another IDE device to make connecting it easier. You can see it working in the demo video on YouTube). For uRTC I was confident enough to lay the board out and get it fabricated (and it worked), but I would not advocate doing this on an entirely new design. uRTC has the same I/O selection logic as uIDE so it was proven from my perspective.
« Last Edit: 20:02, 23 September 19 by JonB »