Z1a - The Future

This project has taken a back seat for a while due to Real Life and Other Things, but there are still many things I'd like to (maybe) get around to at some point:

Keyboard

• Get a stabiliser kit for the wobbly spacebar.
• Ideally, I'd like some key caps with a more retro look.

Software

• Add some more features to the BASIC, including arrays and floating-point maths.
• Port the CP/M operating system to the Z1a.
• Try using the Z180's onboard DMA controllers to speed up things like screen-clearing and scrolling.

Audio

• Add a sound card. A bit tricky this one, because I want something a little more sophisticated than the ZX Spectrum's 1-bit beeper, but old-school sound chips are no longer in production, and I don't want to cheat like I did with the video card. It turns out that the Intel 8253 timer chip, which drove the speaker in older IBM-compatible PCs, is still in production, so I might do something with one of those.
• Add a MIDI port or two.

Video

• Maybe add some new features:
  • Fix the unevenly-sized pixels by adding left and right borders.
  • Add a 512x240 16-colour video mode, so there's an 80-column mode for CP/M software that needs it.
  • Add a 256x240 16-colour video mode, so there's enough VRAM for double-buffering.
  • Add a PAL-compatible timing mode, to output old-school composite video or RGB over SCART
• Redesign the video card. The microcontroller feels like cheating, so I'd like to use discrete logic instead. I might have to use surface-mount chips, which would widen the available range of chips and let me fit more in the available space.

Other I/O

• Add a parallel printer port (my current inkjet is old enough to still have a parallel port!).
• Redesign the I/O board with a proper 16-bit IDE interface, so it can access the whole of a drive.

General

• Rebuild the whole thing as a more compact, possibly single-board (or single-board plus video board) design.
• Put it in some kind of case.