Commit Graph

5 Commits

Author SHA1 Message Date
Virgil Dupras
2b7abf802f pcat: begin porting forth
I'm not sure yet where I'm going, but I'm not going to build the
8086 port from the ground up like I did with the z80, that is,
making is sustain itself and eventually merge its forth code with
core words. That would be too much work which would then be thrown
out (all those words I'll initially have to implement in asm which
are already implemented in Forth).

What I *think* I can do is build a mirror version of z80 boot code
and cross-compile it from the z80. This means it has to follow z80
stable ABI.

Nope, I'm not sure where I'm going...
2020-06-13 21:37:54 -04:00
Virgil Dupras
1a467efae1 pcat: use a far jump to boot into the OS
Unless I misunderstood, this is supposed to set CS. This would make
all SREG have the same value. This allows us to remove BIN( offset
from os.bin.

I've tried booting to offset 0, but it didn't seem to work. Let's
settle for 0x8000. 512kb of system RAM is way more than we need
anyways.
2020-06-13 20:06:51 -04:00
Virgil Dupras
507c2c12e7 8086asm: clarify operands and fix stupidities 2020-06-13 17:58:42 -04:00
Virgil Dupras
5033f17be2 8086asm: tidy up a bit 2020-06-13 16:21:56 -04:00
Virgil Dupras
07e50313c7 pcat: separate MBR code and OS code
MBR code now strictly loads OS code into memory and jumps into it.

Now, I've got to consolidate my assembler code, modrm logic is
messed up.
2020-06-13 15:35:16 -04:00