219 lines
2.3 KiB
NASM
219 lines
2.3 KiB
NASM
ORG BIOS
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CPU 8086
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DISKCX: EQU 0x8
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DISKDX: EQU 0xA
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DISKBX: EQU 0xC
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JMP NEAR BOOT
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JMP NEAR WBOOT
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JMP NEAR CONST
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JMP NEAR CONIN
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JMP NEAR CONOUT
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JMP NEAR LIST
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JMP NEAR PUNCH
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JMP NEAR READER
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JMP NEAR HOME
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JMP NEAR SELDSK
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JMP NEAR SETTRK
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JMP NEAR SETSEC
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JMP NEAR SETDMA
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JMP NEAR READ
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JMP NEAR WRITE
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JMP NEAR LISTST
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BOOT:
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MOV AL, 0x86
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CALL MSG
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DB "BIOS", 0
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WBOOT:
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XOR CX, CX
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JMP BDOS
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RET
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; CHAR I/O
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CONST:
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MOV AH, 1
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INT 0x16
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JZ .END
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MOV AL, 0xFF
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RET
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.END:
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XOR AL, AL
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RET
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CONIN:
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XOR AX, AX
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INT 0x16
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TEST AL, AL
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JZ CONIN
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RET
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MSG:
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POP SI
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.LOOP:
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MOV DL, BYTE [SI]
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INC SI
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TEST DL, DL
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JZ .END
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CALL CONOUT
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JMP .LOOP
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.END:
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MOV DL, 0x20
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CALL CONOUT
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CALL PRINTAL
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MOV DL, 0x0A
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CALL CONOUT
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MOV DL, 0x0D
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CALL CONOUT
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PUSH SI
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RET
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PRINTAL:
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PUSH AX
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PUSH DX
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AAM 16
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MOV DL, AH
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CALL PRINTNIB
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MOV DL, AL
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CALL PRINTNIB
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POP DX
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POP AX
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RET
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PRINTNIB:
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ADD DL, 0x30
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CMP DL, 0x3a
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JL CONOUT
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ADD DL, 0x07
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CONOUT:
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PUSH AX
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PUSH BX
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MOV AH, 0x0E
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MOV AL, DL
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XOR BX, BX
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INT 0x10
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POP BX
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POP AX
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RET
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LIST:
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PUSH DX
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XOR AH, AH
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MOV AL, DL
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INT 0x17
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POP DX
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RET
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LISTST:
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STC
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RET
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PUNCH:
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STC
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RET
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READER:
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STC
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RET
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; DISK I/O
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HOME:
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MOV WORD [DISKCX], 0x0001
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MOV BYTE [DISKDX+1], 0x00
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RET
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SELDSK:
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MOV BYTE [DISKDX], CL
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XOR BX, BX
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RET
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SETTRK:
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PUSH CX
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PUSH DX
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MOV DX, CX
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; CH for headnum, CL for SAL
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MOV CX, 0x0006
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; Take off LSB as head number
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XOR CH, CH
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RCR DX, 1
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RCL CH, 1
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MOV BYTE [DISKDX+1], CH
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; DX is sector number now
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; Shift into format for int13
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; DX ------9876543210
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SAL DX, CL
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; DX 9876543210------
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ROL DX, 1
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ROL DX, 1
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; DX 76543210------98
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SAL DL, CL
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; DX 7654321098------
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AND WORD [DISKCX], 0x003F
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OR WORD [DISKCX], DX
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POP DX
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POP CX
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RET
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SETSEC:
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AND WORD [DISKCX], 0xFFC0
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OR BYTE [DISKCX], CL
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RET
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SETDMA:
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MOV WORD [DISKBX], CX
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RET
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READ:
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PUSH CX
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PUSH DX
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PUSH BX
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MOV AX, 0x0201
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MOV CX, [DISKCX]
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MOV DX, [DISKDX]
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MOV BX, [DISKBX]
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INT 0x13
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XCHG AH, AL
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POP BX
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POP DX
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POP CX
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JC DISKERR
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RET
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WRITE:
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PUSH CX
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PUSH DX
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PUSH BX
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MOV AX, 0x0301
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MOV CX, [DISKCX]
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MOV DX, [DISKDX]
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MOV BX, [DISKBX]
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INT 0x13
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XCHG AH, AL
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POP BX
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POP DX
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POP CX
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JC DISKERR
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RET
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DISKERR:
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PUSHF
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PUSH SI
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CALL MSG
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DB "DISKERR", 0
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POP SI
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POPF
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RET
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