84 lines
2.5 KiB
Plaintext
84 lines
2.5 KiB
Plaintext
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;Making SYMPHONY ver 1.00 to run with out SYMPHONY'S master disk -
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;unprotecting it:
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;
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;A>REN SYMPHONY.CMP SYMPHONY.XXX
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;A>DEBUG SYMPHONY.XXX
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;-R ;find the segment where loaded and add 1000 to it
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; ;DS=0DFA - xxxx=1DFA (0DFAH+1000H=1DFAH)
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;-E xxxx:3A05 75 ;change INT 13 to INT 75H (see label SYMINT below)
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;-W ;save changed file
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;-Q ;exit debuger
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;A>REN SYMPHONY.XXX SYMPHONY.CMP
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;A>SYMPH ;execute THIS PROGRAM (it modifies the changed interupt
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; ;back to 13H since SYMPHONY does checksum of it's self)
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;
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;
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;
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; assemble, link, exe2bin
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;
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;Execute this program before using SYMPHONY.
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;There is no need to re-execute this program after exit from SYMPHONY, in
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;order to use the SYMPHONY again, since it is a resident program
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;
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;
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;to further examine the symphony for possibly other way to solve this, using
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;DEBUG, do:
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;A>DEBUG SYMPHONY.EXE
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;-G2
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;-T3
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;-G8A40
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;-T ;at this point you will find the the subroutine that fills
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; ;location ds:8735 with n and int 13 (the second one) which
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; ;reads the serial number from flopy disk in A. Zeroing 8735
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; ;fools the symphony, and prevents it from testing for special
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; ;track/sector structure on the flopy. If the location 8735 is
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; ;not zeroed, debugging will not be possible after IP 8A4D,
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; ;since INT 3 will be modified by SYMPHONY.
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;
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SYMINT EQU 75H ;interupt to use
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SYMFLG EQU 8735H ;see above for info
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CSEG SEGMENT
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ASSUME CS:CSEG,DS:CSEG
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ORG 100H
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PROGRA: XOR AX,AX
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MOV ES,AX ;set to segment 0 (interupt table)
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XOR DX,DX
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MOV AL,SYMINT ;interupt number
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MOV CX,4 ;get position in interupt table
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MUL CX
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MOV BX,AX
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TEST WORD PTR ES:[BX],0 ;test if set?
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JZ DOIT ;no, go set it
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INT 20H ;exit to dos with out mod
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DOIT: ;get interupt routine address
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MOV word ptr ES:[BX],offset corc ;store it at the apropriate int address
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MOV ES:[BX+2],CS ;also store the segment
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MOV DX,5+16 ;lenght of this pgm in segments
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MOV AX,3103H ;exit & stay resident
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INT 21H
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;this is the actual interupt
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CORC: CLI
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PUSH ES ;save all used registers
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PUSH BP
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PUSH BX
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MOV BP,SP
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MOV ES,[BP+8] ;get calling segment from stack
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MOV BX,[BP+6] ;get calling address from stack
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DEC BX ;back up one
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MOV BYTE PTR ES:[BX],13H ;store interupt 13h there
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MOV BYTE PTR DS:SYMFLG,0 ;zero out the flopy test flag
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POP BX ;restore registers
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POP BP
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POP ES
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STI
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IRET ;back to symphony
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CSEG ENDS
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END PROGRA
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