;--------------------------------------------------------------------------- ; W A T K I N T E C H N O L O G Y S o f t w a r e D i v i s i o n ;--------------------------------------------------------------------------- ; PROGRAM: Bootable Mini Monitor for PC ; VERSION: 1.0 PLATFORM: 8088+ ; PROJECT: USB Pendrive Booting FILE: MINIMON .ASM ; AUTHOR: Neville Watkin DATE: 14 Jan 2011 ; NOTES: Assemble with fasm to MINIMON.IMG ; Remove/replace DOS test code for bootsector version! See **** ;--------------------------------------------------------------------------- ; Revision History ;14.01.11 initial release ;--------------------------------------------------------------------------- ; ORG 0100H ;for pre-testing with DOS **** ORG 7C00H ;boot version JMP MINIMON NOP MINIMON: ; JMP 0000H:START ;add later if room to ensure CS=0 ;START: MOV AX,3 ;could assume this to save 5 bytes? INT 10H PUSH 0 POP DS ;ds=0 initially ; TIMES 9 DB 90H ;dummy code replaced below **** MOV DWORD[14H],00007C00H ;set INT5 vector boot version AGAIN: MOV BX,WORD[CS:MEMADDR] ;shift start offset to BX MOV SI,BX ;save a copy MOV BL,0 ;low 8 bits of address = 0 MOV DX,0803H ;start memory dump at line 8, col 3 CALL SETCURS PUSH CX MOV CX,10H ;16 lines per dump LINE: PUSH CX ; MOV CX,10H ;16 bytes per line MOV CL,10H ;16 bytes per line - 1 byte! MOV AX,DS ;get MS high offset byte ROL AX,4 CALL BYTE2ASC ;convert to ascii hex MOV AL,BH ;get LS high offset byte CALL BYTE2ASC MOV AL,BL ;get low offset byte CALL BYTE2ASC RDMEM: PUSH BX MOV BX,7 MOV AX,0E20H INT 10H POP BX MOV AL,[BX] ;get byte from memory CALL BYTE2ASC ;convert to ascii-hex INC BX LOOP RDMEM ;and repeat for 16 bytes POP CX INC DH ;increase line number MOV DL,03H ;reset column (instead of CRLF) CALL SETCURS LOOP LINE ;repeat for all lines POP CX MOV DX,[CS:CURLOC] ;set cursor for editing CALL SETCURS GETBYTE: PUSH CX CALL GETNYBL ;get MS Digit JC CMD ;command key if c set MOV CH,AL ;save in ch CALL HEXDIGIT ;convert back to ascii MOV AH,0EH INT 10H CALL GETNYBL ;get LS Digit JC CMD MOV CL,AL ;save in cl CALL HEXDIGIT ;convert back to ascii MOV AH,0EH INT 10H MOV AL,CH ;retrieve binary MSD SHL AL,4 ;shift to bits 4-7 OR AL,CL ;merge with bits 0-3 ; MOV BX,WORD[CS:MEMADDR] ;get start addr again MOV BX,SI ;get start addr again MOV [BX],AL JMP INCBYTE ;and update curloc & edit address CMD: POP CX ; CMP AL,01H ;ESC? DOS test only +4 bytes **** ; JZ EXIT CMP AL,51H ;PgDn? LS low offset increase JZ INCLSL CMP AL,49H ;PgUp? LS low offset decrease JZ DECLSL CMP AL,4FH ;End key? Segment increase JZ INCSEG CMP AL,2DH ;x or X? JZ EXEC0100 ;execute from edit addr with IP=0100 ;(so can also pre-test code in DOS) MOV DX,[CS:CURLOC] ;assume editing control command CMP AL,4DH ;next byte for editing -> JZ INCBYTE CMP AL,4BH ;next byte for editing <- JZ DECBYTE CMP AL,50H ;next para for editing <- JZ INCPARA CMP AL,48H ;next para for editing <- JZ DECPARA JMP CMDDONE INCLSL: INC BYTE[CS:MEMADDR+1] JMP CMDDONE DECLSL: DEC BYTE[CS:MEMADDR+1] JMP CMDDONE INCSEG: PUSH DS POP AX ADD AX,1000H MOV DS,AX JMP CMDDONE ;EXEC0100: MOV BX,WORD[CS:MEMADDR] ;get start addr again EXEC0100: MOV BX,SI ;get start addr again SUB BX,100H ;use offset 0000 to save these bytes? SHR BX,4 ;must be on para boundary! MOV AX,DS ADD AX,BX ;derive CS MOV WORD[CS:EXECSEG],AX ;setup CS JMP EXECPROG ;set CS,IP - see you later! INCBYTE: INC WORD[CS:MEMADDR] ADD DL,03H MOV [CS:CURLOC],DX CMP DL,37H JA INCBYTE1 JMP CMDDONE INCBYTE1: MOV DL,0AH INC DH MOV [CS:CURLOC],DX CMP DH,17H JA INCBYTE2 JMP CMDDONE INCBYTE2: MOV DX,080AH MOV [CS:CURLOC],DX JMP CMDDONE DECBYTE: DEC WORD[CS:MEMADDR] SUB DL,03H MOV [CS:CURLOC],DX CMP DL,0AH JB DECBYTE1 JMP CMDDONE DECBYTE1: MOV DL,37H DEC DH MOV [CS:CURLOC],DX CMP DH,08H JB DECBYTE2 JMP CMDDONE DECBYTE2: MOV DX,1737H MOV [CS:CURLOC],DX JMP CMDDONE INCPARA: ADD WORD[CS:MEMADDR],10H INC DH MOV [CS:CURLOC],DX CMP DH,17H JA INCPARA2 JMP CMDDONE INCPARA2: MOV DH,08H MOV [CS:CURLOC],DX JMP CMDDONE DECPARA: SUB WORD[CS:MEMADDR],10H DEC DH MOV [CS:CURLOC],DX CMP DH,08H JB DECPARA2 JMP CMDDONE DECPARA2: MOV DH,17H MOV [CS:CURLOC],DX CMDDONE: JMP AGAIN ;1 long jump, saves 10 bytes! ;EXIT: ; INT 20H ;DOS test only +2 bytes **** ;---------------------------------------------------------------------------- ;Subroutines ;---------------------------------------------------------------------------- SETCURS: PUSH AX ;save reqd char PUSH BX MOV AH,02 MOV BX,7 INT 10H POP BX POP AX ;restore reqd char in al RET GETNYBL: CLC ;clear carry MOV AH,0 INT 16H CMP AL,0 ;allow all cursor keys as commands JZ CMDKEY CMP AL,1BH ;Esc? JZ CMDKEY CMP AL,30H ;ignore if < "0" JB GETNYBL CMP AL,66H ;allow all lowercase > "f" as cmds JA CMDKEY CMP AL,61H ;valid lowercase if a - f JAE LOWCASE CMP AL,46H ;allow all uppercase F-Z as commands JA CMDKEY CMP AL,41H ;valid uppercase if A - F JAE UPCASE CMP AL,39H ;ignore if between 9 and A JA GETNYBL SUB AL,30H ;must be 0 - 9, convert to binary JMP GOTNYBL LOWCASE: SUB AL,57H ;must be a - f. convert to binary JMP GOTNYBL UPCASE: SUB AL,37H ;must be A - F, convert to binary JMP GOTNYBL CMDKEY: STC ;set Carry flag for command key MOV AL,AH ;check scan codes using AL, GOTNYBL: RET ;saving 1 byte each time BYTE2ASC: PUSH BX ;save RAM pointer PUSH AX ;save binary data SHR AL,4 ;get high nybble CALL HEXDIGIT ;and convert to ascii-hex MOV BH,AL ;save MSD in bh POP AX ;retrieve binary data AND AL,0FH ;get low nybble CALL HEXDIGIT ;and convert to ascii-hex MOV AH,BH ;restore MSD to ah DBYTE: PUSH DX PUSH CX MOV BX,0007H ;page 0, colour = white MOV CX,AX ;save data in cx MOV AH,0EH MOV AL,CH INT 10H MOV AL,CL MOV AH,0EH INT 10H POP CX POP DX POP BX RET HEXDIGIT: ADD AL,30H CMP AL,3AH JB HEXDIGID ADD AL,07 HEXDIGID: RET MEMADDR: DW 7C00H CURLOC: DW 080AH ;cursor location for editing EXECPROG: DB 0EAH ;JMP command EXECOFFS: DW 0100H ;default offset always 0100H EXECSEG: DW 07B0H ;default seg ) = 07B00100H this program! TIMES 7C00H+510-$ DB 0 ;4 bytes spare! ; DB 0 DB 55H, 0AAH