Building The ZX Raspberry – Part Four

In which our hero is unable to leave well alone

A little epilogue to the ZX Raspberry project. I came into possession of a very dead ZX Spectrum+ and, following my own personal rule of ‘it gets fixed or it gets modded’, I decided that it was time for a ZX Raspberry+. This project did away with the USB keyboard option, so just a standalone Raspberry Pi-driven unit.

ZX Raspberry+ Innards

ZX Raspberry+ Innards

I made a few improvements and discoveries along the way.

  1. It’s a lot easier to put all this gubbins in a Plus case rather than an original.
  2. The Raspberry PI + variant (+ or 2) is conveniently sized to place the HDMI and power alongside the expansion port (less cables!).
  3. The +’s reset switch makes a handy keyboard mode switch.
  4. A conclusion I reached during the first project was right, I didn’t need the resistors on KB1. Leave them and the power line out, wire the connector directly to the Pro Micro and just set the inputs to INPUT_PULLUP in the Arduino sketch. It does everything for you.

Finally, I was able to really speed up boot time by using PipaOS instead of the standard Rasbian distribution. It’s still Raspbian, but optimised for fast bootup and without a lot of the stuff you don’t need anyway. The results on a Raspberry PI 2 with a Class 10 SD card are quite something. Here’s a boot video:

Just a shade over 10 seconds. Not bad eh?

 

Building The ZX Raspberry – Part One

In which our hero plans and schemes

Despite wanting to convert a ZX Spectrum into a USB keyboard for some time, I held off to wait for the unlikely duo of the ZX Spectrum Vega and the Recreated ZX Spectrum. Sadly, neither buttered my parsnips, and the reasons why have been discussed at length around this Internet of ours, so I shall say no more here. What I really wanted a combination of the two: The stand-alone operation of the Vega and the keyboard of the ‘Recreated’.

Not being one to re-invent the wheel, I’d been reading over this Instructable wot I found and occasionally drooling over the excellent kits offered by Tynemouth Software. Then, a battered old Speccy case and the parts needed for a USB interface found their way onto a Facebook group for just £20, their current owner being caught between retro-project-awesomeness and ‘having a life’ and ‘friends’. Clearly making the wrong choice, he put them up for sale. … 

 

3D-Printed Tooth

I’ve often wondered when my first ‘real life’ 3D printing experience would come. I’ve been lucky enough to see a few printers in action, indeed there’s one at The National Museum of Computing,  but these have all worked as demonstrations of the technology, printing out head scans, chess pieces and the like. When would 3D printing actually have an impact on my life?

The answer came sooner than expected. … 

 

iCade Hacking

I realised I hadn’t used the iCade for a while. This arcade housing for the iPad was a lot of fun for the first few weeks, but I had got tired of the ‘gotchas’ such as the inability to run iMame4All without some significant work (and even then, it didn’t work as so well). Time to get out the screwdriver.

I had an old netbook, a Compaq Mini 110, that was enjoying a comfortable retirement in the parts bin. After a bit of head scratching and holding-things-up-to-other-things I had an idea: Turn the iCade into a standalone MAME console. After all the switchgear is great and probably very easy to hack, right?

Step One: Turn the iCade’s controls into a USB device. The iCade uses bluetooth to talk to the iPad as a remote keyboard. Opening up the control box, I found what i’d hoped to: a series of simple switches wired into a small PCB.

My parts bin also threw up an old Saitek USB games controller that was no longer required. Once the screwdriver had it’s way with it, I found a very well-labelled PCB inside wired by small ribbon cables to PCBs that held the buttons.

Couldn’t have been more convenient. In fact, the wiring was so good I decided to let the soldering iron rest and just used 3A terminal blocks to link everything together. It was delicate work but, following a few false starts, I was able to use the iCade’s controls as a USB device and Windows was perfectly happy with it.

Getting it all back in the box was a little more problematic, the Saitek PCB was much larger than the bluetooth one, so the piece of plastic that acts as a riser for the iPad’s USB cable had to go. To the Dremel!

A small widening of the original power socket aperture later and the USB cable fits through. I was able to reassemble the control unit, which is now a normal USB joystick.

Next, the computing part.  Following a YouTube video, I was able to disassemble the laptop, remove the hinges, then discard all of the housing around the LCD screen. Then, I could put the lower part back together. We now have half of the netbook as normal, but no upper half, just a some wires leading to the screen, camera, speakers and wifi antennas. I very delicately checked it was still working and happy (phew) then set to work on the iCade case.

By cutting a notch in the side of the back plate of the iCade, I was able to feed the screen data and power wires through, so the screen would sit centrally. Then the lower part of the netbook could be bent back to lie against the rear of the plate, effectively opening the netbook up 360 degrees. I affixed the screen using some screws and the lower assembly on the reverse side using Scotch sticky mounts (wonderful things).

The iCade can now be reassembled! Once together , it was now on to software. I decided on Windows XP as it was the OS the netbook was designed for. I reckoned Windows 7 might overawe the ikkle Atom processor and don’t even talk to me about Windows 8. Ubuntu got the boot (or not) as well as driver support for the Mini 110, especially wifi, is flakey.

Windows XP meant I could use GameEx, a truly wonderful front-end for these kind of projects. It’s a scary beast to configure but is probably the most customisable of it’s type. The answer to ‘I wonder if you can’ is invariably ‘yes, and we’ve thought of a few other ways of doing it too’. For instance, a requirement was going to be screen rotation and that was a doddle.

So, GameEx installed, MAME installed and controls configured to the iCade. No real challenges there. Load up some roms and we have our first test. Of course, there could only be one game to try out for a first run.

Hmm. The screen is a bit ugly. I purchased some thick mounting card from the local hobby shop and cut it to size. We’re done. Time for the tester to get involved.

Final tweak I’ll probably make is to get a battery for the netbook and then this puppy is portable! It’s going to be a retro Christmas at Evans Towers.