Category : Unprotects for Games and Such
Archive   : ULTIMA5.ZIP
Filename : U.ASM

VECTORS SEGMENT AT 0H
ORG 13H*4 ; INTERUPT 13
VECT13_LOC LABEL DWORD
VECTORS ENDS

CODE_SEG SEGMENT
ASSUME CS:CODE_SEG
ORG 100H

BEGIN: JMP INIT_VECTORS

OLD_INT13_VECT DD
TEMP DW

INTERCEPT_INT13 PROC NEAR
ASSUME CS:CODE_SEG
PUSHF
PUSH ES
PUSH DS
PUSH SI
PUSH DI
PUSH CX
PUSH DX
PUSH BX
MOV TEMP,AX ; STORE CALL IN CASE IT IS NOT ULTIMA V CALL
CMP AX,0404H ; IS THE CALL FOR A VERIFY SECTORS
JNZ CHECK_INT2 ; IF NOT VERIFY SECTORS CHECK FOR READ SECTORS
CMP DX,0000H
JNZ CHECK_INT2
CMP CX,0602H
JZ VERIFY_SECTORS
CMP CX,06BBH
JNZ CHECK_INT2
; THIS ROUTINE NOW IS TO VERIFY SECTORS, SIMPLY RETURN A SUCCESS CODE
VERIFY_SECTORS:
MOV AX,0000H
JMP EXIT

CHECK_INT2:
CMP AX,0201H ; IS CALL FOR READ IN SECTORS
JNZ REAL_INT ; THE CALL IS NOT ULTIMA V SO CALL REAL INTERUPT
CMP BX,0318H
JNZ REAL_INT
CMP CX,0601H
JNZ REAL_INT
CMP DX,0000H
JNZ REAL_INT
MOV AX,04E4EH
MOV DI,BX
MOV CX,0100H/2
LOAD_4E:
STOSW
LOOP LOAD_4E
MOV AX,0322H
STOSW
MOV AX,072DH
STOSW
MOV AX,0800H
STOSW
MOV AX,01B3BH
STOSW
MOV AX,0000H
MOV CX,0F6H/2
LOAD_00:
STOSW
LOOP LOAD_00
MOV AX,4E00H
STOSW
JMP EXIT

REAL_INT:
POP BX
POP DX
POP CX
POP DI
POP SI
POP DS
POP ES
CALL OLD_INT13_VECT ; YOU DO NOT POPF TO MAINTAIN STACK INTEGRITY
IRET

EXIT:
POP BX
POP DX
POP CX
POP DI
POP SI
POP DS
POP ES
POPF
MOV AX,0000H ; RETURN NO ERROR CODE
IRET

INTERCEPT_INT13 ENDP

INIT_VECTORS PROC NEAR
ASSUME DS:VECTORS
MOV AX,VECTORS
MOV DS,AX
MOV AX,VECT13_LOC
MOV OLD_INT13_VECT,AX
MOV AX,VECT13_LOC[2]
MOV OLD_INT13_VECT[2],AX
MOV VECT13_LOC, OFFSET INTERCEPT_INT13
MOV VECT13_LOC[2], CS
MOV AX,CS
MOV DS,AX
MOV DX, OFFSET INIT_VECTORS
INT 27H ; DOS FOR MEMORY RESIDENT PROGRAMS
INIT_VECTORS ENDP

CODE_SEG ENDS
END BEGIN