As promised I got the new, simplified keyboard interface working this weekend. This means that COLE-2 can now operate as a fully standalone computer; no serial console needed. Of course, it’s still not terribly useful, because the only thing in ROM is the system monitor, but it’s a good start!
Overall I am very happy with the new design. It’s more or less what I described in my last post, with one small exception. In the new version, pressing one of the toggle keys (CapsLock, NumLock, and ScrollLock) is still handled inside the AVR. When a key down on one of those keys is detected, it will toggle the LED state, and then send the BIOS either a key down or key up code, depending on the new state of the LED. In other words, as far as the BIOS is concerned, the toggle keys are just regular modifier keys, albeit ones with longer-than-normal key down times.
Mouse and game pad support are not yet implemented, though the new firmware is driving both PS/2 ports now. These features, and some improvements to support hot plug and device detection, are on my list for future development.
With the keyboard finally working I’m going to bite the bullet and start cleaning up the BIOS. Specifically, I need to nail down a formal API and drive model so that I can start working on the OS and the BASIC interpreter application. We’ll see how that goes. 🙂