collapseos/blk/811

H@ ORG ! 0x7c00 BIN( ! ( BIOS loads boot bin at 0x7c00 )
JMPs, L1 FWRs ( start )
ORG @ 0x25 + HERE ! ( bypass BPB )
L1 FSET ( start )
CLI, CLD, AX 0x800 MOVxI, DS AX MOVsx, ES AX MOVsx,
SS AX MOVsx, DX PUSHx, ( will be popped by OS ) STI,
AH 2 MOVri, DH 0 MOVri, CH 0 MOVri, CL 2 MOVri, AL 15 MOVri,
BX 0 MOVxI, 0x13 INT, ( read sectors 2-15 of boot floppy )
( TODO: reading 12 sectors like this probably doesn't work
  on real vintage PC/AT with floppy. Make this more robust. )
0x800 0 JMPf,
ORG @ 0x1fe + HERE ! 0x55 A, 0xaa A,
recipes/pcat: first steps into 8086! 2020-06-13 04:01:24 +10:00			`H@ ORG ! 0x7c00 BIN( ! ( BIOS loads boot bin at 0x7c00 )`
8086asm: tidy up a bit 2020-06-14 06:21:56 +10:00			`JMPs, L1 FWRs ( start )`
recipes/pcat: now tested on real hardware! 2020-06-14 01:47:32 +10:00			`ORG @ 0x25 + HERE ! ( bypass BPB )`
recipes/pcat: first steps into 8086! 2020-06-13 04:01:24 +10:00			`L1 FSET ( start )`
8086asm: add support for modrm 8-bit displacement 2020-06-15 20:52:47 +10:00			`CLI, CLD, AX 0x800 MOVxI, DS AX MOVsx, ES AX MOVsx,`
pcat: use boot drive no passed to bootloader through DL instead of hardcoded drive 0. 2020-06-22 12:53:11 +10:00			`SS AX MOVsx, DX PUSHx, ( will be popped by OS ) STI,`
			`AH 2 MOVri, DH 0 MOVri, CH 0 MOVri, CL 2 MOVri, AL 15 MOVri,`
pcat: BLK-enabled! That INT 13H logic was a bit tricky to implement... read-only for now. 2020-06-22 12:07:12 +10:00			`BX 0 MOVxI, 0x13 INT, ( read sectors 2-15 of boot floppy )`
pcat: we have PROMPT! Not working, but we do get that sweet "CollapseOS". 2020-06-21 06:58:48 +10:00			`( TODO: reading 12 sectors like this probably doesn't work`
			`on real vintage PC/AT with floppy. Make this more robust. )`
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. 2020-06-14 10:06:51 +10:00			`0x800 0 JMPf,`
recipes/pcat: now tested on real hardware! 2020-06-14 01:47:32 +10:00			`ORG @ 0x1fe + HERE ! 0x55 A, 0xaa A,`