C64 modding on

(Part IV of an ongoing series)

A couple of things have been done to the boxed C64.


Arduino programmer port

The PS/2 keyboard adapter is Arduino-based, which still needs updating. I moved the Arduino USB connector, and added a switch for turning off the power line to the C64, so the Arduino can be programmed with the cover on using the normal USB-B cable.

However I still wouldn't dare hot-plug the thing, but at least I don't have to pull the cable out of the motherboard every time.

Left: The cartridge button, Right: The programmer port

This setup helped me in repairing the keyboard adapter code a bit faster. The keymap corresponds better with my "Deltaco" PS/2 mini keyboard, and it's less prone to freezing. It works fine with many kinds of applications.

I also tried to use one of the alternative keymaps to route the arrow keys to correspond with the joystick 1 directions. You know, if you turn the stick in C64 BASIC you get 1,2, <-, space ... This would be nice as then I could keep a joystick only in port 2 and play those rare 1-port games with the keyboard. And the approach does work, for example, in my copy of Cosmic Causeway and Falcon Patrol 2 the adapter gives excellent control.

But in Boulder Dash and IK+, the approach did not work. This is likely because although the joystick port reading has been (unofficially) mapped to various addresses, the keyboard does not come in with the deal. If the game uses those other addresses, it won't work. Well, a nice idea anyway.


Front Panel Cartridge button

I added a cartridge function button to the front panel. The downside of this boxed model is the cart buttons tend to be too far to operate, so this became a necessity.

The contact wires are pulled back below the motherboard, to the vicinity of the cartridge port, from where they are connected to the cart. This requires a small wiring mod to the cartridge too. The IRQHack64 cartridge has a programmer port with GND, but the other pin needed to be brought out with a separate wire.

Crudeness at the backside. The pins connect the cartridge wires brought from under the motherboard.

As an aside, I transferred a fair amount of one-file game prgs to the IRQHack, and more than 80% of them run. This gives me a more positive impression of this cart than my unlucky first experiences indicated. Even in the cases where the game doesn't run, more often than not I can find an image that works.

I'd like to bring the IRQHack SD-card reader to the front, and possibly change it to normal size SD, but this would be a huge commitment to that cartridge, and extending all sorts of cables might not be such a good idea. Updating the IRQHack menu could be on the schedule too, but that requires some more effort.


In hindsight

All in all, I'm starting to see certain weaknesses in this box layout. Mostly the problems could be overcome with the above additions. It could have been smarter to make the additions to a proper breadbox model, like others have done, but this project apparently isn't entirely about smartness.

At least Chessmaster 2100 can be played with the keyboard...

I now have the more finished product C-keys adapter, but whether I will use it in this project or not, remains to be seen. Having the Arduino here gives more freedom and flexibility, but likely the finished adapter simply works better.

The needed changes point towards a further iteration of the box. I might have been on the right track when I thought about more unconventional board positioning, the cartridge at rear isn't exactly the best place for it now.

Again, more pre-planning might have helped in this matter. For example, a pre-emptive "network" of wires and connectors somewhere below the board could have been useful too, as now each new function needs improvised wiring and holes within the box.

Part I

Part II

Part III