I was wrong in commit 7437 that only one keystroke was working. The problem
was just that I was getting _too_ many events. I wasn't handling key-up
events, and they were entering the buffer, and I was not skipping null
events since the circular buffer is currently considered to be null-terminated.
ex3 isn't done yet; it can only handle 16 events. Apps need to be clearing
the keyboard buffer.
The ol' 8-byte-register-names issue strikes again. There's no way to access
the lower 8 bits of ESI.
There's still a bug in baremetal/ex2.mu; it's printing transposed somehow.
I'm trying to read the status register, but I'm still not seeing the breakpoint
being hit a second time. (And I again ran into the Bochs bug that breakpoints
at the first instruction of an interrupt handler don't work.)
Maybe this is just a debugger issue. Let's keep going, and try to start
using the keyboard events.
I'd missed that VBE call 0x4f01 (get video mode) can write up to 256 bytes.
Unexpected areas were getting clobbered because I wasn't reserving enough
space.
If it's large enough that I have doubts whether my top-of-the-line Mac
is showing the bottom of the screen inside an emulator, it's too large.
This way I also feel more confident that most modern hardware will support
this graphics mode, and that these programs will work for others.
We need a few pages of data for the keyboard mappings.
If I moved them to some later address I'd be able to keep the nice round
starting address unchanged. But that seems like a superficial aesthetic
concern. There's really no value in having an array of hex bytes represented
in SubX rather than just raw hex. And it's better to colocate data near
the handler code which uses it (and which runs instructions SubX doesn't
support).
