874 B
Debugging Notes
The boot sector contains the following code:
0000:7C3E B003 MOV AL,03 0000:7C40 B200 MOV DL,00 0000:7C42 B417 MOV AH,17 0000:7C44 CD13 INT 13 0000:7C46 72B8 JC 7C00
For BIOSes that don't support INT 0x13, AH function 0x17, patch the JC with two NOPs; eg:
e 0:7c46 90 90
After booting, the following code is executed:
12E8:01D3 52 PUSH DX ;history=5 12E8:01D4 51 PUSH CX ;history=4 12E8:01D5 2BC9 SUB CX,CX ;history=3 12E8:01D7 BA6400 MOV DX,0064 ;history=2 12E8:01DA ED IN AX,DX ;history=1
For virtual machines that don't support word I/O to port 0x64, patch IN AX,DX with IN AL,DX; eg:
e 12e8:1da ec