diff options
| -rw-r--r-- | boot.subx | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/boot.subx b/boot.subx index 0c525b68..ee76636e 100644 --- a/boot.subx +++ b/boot.subx @@ -97,22 +97,23 @@ 8e/seg-> 3/mod/direct 3/rm32/bx 0/r32/es bb/copy-to-bx 0x7e00/imm16 cd/syscall 0x13/imm8/bios-disk-service - == data 0f 82 a3 00 # jump-if-carry disk_error [label] +== code # load two more tracks of disk into addresses [0x17800, 0x27400) - b4 02 # ah <- 2 # read sectors from disk + b4/copy-to-ah 2/imm8 # read sectors from disk # dl comes conveniently initialized at boot time with the index of the device being booted - b5 00 # ch <- 0 # cylinder 0 - b6 02 # dh <- 2 # track 2 - b1 01 # cl <- 1 # first sector, 1-based - b0 7e # al <- 126 # number of sectors to read = 2*63 - # address to write sectors to = es:bx = 0x17800 - bb 80 17 # bx <- 0x1780 [label] - 8e c3 # es <- bx - bb 00 00 # bx <- 0 - cd 13 # int 13h, BIOS disk service + b5/copy-to-ch 0/imm8 # cylinder 0 + b6/copy-to-dh 2/imm8 # track 2 + b1/copy-to-cl 1/imm8 # first sector, 1-based + b0/copy-to-al 0x7e/imm8 # number of sectors to read = 2*63 = 126 + # address to write sectors to = es:bx = 0x17800, contiguous with boot segment + bb/copy-to-bx 0x1780/imm16 + 8e/seg-> 3/mod/direct 3/rm32/bx 0/r32/es + bb/copy-to-bx 0/imm16 + cd/syscall 0x13/imm8/bios-disk-service +== data 0f 82 9b 00 # jump-if-carry disk_error [label] # load two more tracks of disk into addresses [0x27400, 0x37000) |