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150 lines
2.9 KiB
150 lines
2.9 KiB
;----------------------------------------------------------------------------
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; PREFIX_UNA.ASM
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;
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; PUT AT THE HEAD OF BOOT.BIN TO XFER TO A FLOPPY DISK
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;
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;----------------------------------------------------------------------------
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#INCLUDE "std.asm"
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BYT .EQU 1 ; used to describe METADATA_SIZE below
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WRD .EQU 2
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SECTOR_SIZE .EQU 512
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BLOCK_SIZE .EQU 128
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PREFIX_SIZE .EQU (3 * SECTOR_SIZE) ; 3 SECTORS
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METADATA_SIZE .EQU BYT+WRD+(4*BYT)+16+BYT+WRD+WRD+WRD+WRD ; (as defined below)
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.ORG $8000
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JR BOOT
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;
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BOOT:
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LD DE,STR_LOAD ; LOADING STRING
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CALL PRTSTR ; PRINT
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CALL PRTDOT ; PROGRESS
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;
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LD BC,$00FC ; UNA FUNC: GET BOOTSTRAP HISTORY
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CALL $FFFD ; CALL UNA
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JR NZ,ERROR ; HANDLE ERROR
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CALL PRTDOT ; PROGRESS
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LD B,L ; MOVE BOOT UNIT ID TO B
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;
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LD C,$41 ; UNA FUNC: SET LBA
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LD DE,0 ; HI WORD ALWAYS ZERO
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LD HL,3 ; IMAGE STARTS AT FOURTH SECTOR
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CALL $FFFD ; SET LBA
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JR NZ,ERROR ; HANDLE ERROR
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CALL PRTDOT ; PROGRESS
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;
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LD C,$42 ; UNA FUNC: READ SECTORS
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LD DE,$D000 ; STARTING ADDRESS FOR IMAGE
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LD L,22 ; READ 22 SECTORS
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CALL $FFFD ; DO READ
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JR NZ,ERROR ; HANDLE ERROR
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CALL PRTDOT ; PROGRESS
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;
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LD DE,STR_DONE ; DONE MESSAGE
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CALL PRTSTR ; PRINT IT
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;
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LD D,B ; PASS BOOT UNIT TO OS
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LD E,0 ; ASSUME LU IS ZERO
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JP CPM_ENT ; GO TO CPM
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;
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PRTCHR:
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PUSH BC
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PUSH DE
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LD BC,$0012 ; UNIT 0, WRITE CHAR
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LD E,A ; CHAR TO PRINT
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CALL $FFFD ; PRINT
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POP DE
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POP BC
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RET
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;
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PRTSTR:
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PUSH BC
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PUSH HL
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LD BC,$0015 ; UNIT 0, WRITE CHARS UNTIL TERMINATOR
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LD L,0 ; TERMINATOR IS NULL
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CALL $FFFD ; PRINT
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POP HL
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POP BC
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RET
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;
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PRTDOT:
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LD A,'.' ; DOT CHARACTER
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JR PRTCHR ; PRINT AND RETURN
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;
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; PRINT THE HEX BYTE VALUE IN A
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;
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PRTHEXBYTE:
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PUSH AF
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PUSH DE
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CALL HEXASCII
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LD A,D
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CALL PRTCHR
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LD A,E
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CALL PRTCHR
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POP DE
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POP AF
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RET
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;
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; CONVERT BINARY VALUE IN A TO ASCII HEX CHARACTERS IN DE
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;
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HEXASCII:
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LD D,A
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CALL HEXCONV
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LD E,A
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LD A,D
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RLCA
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RLCA
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RLCA
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RLCA
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CALL HEXCONV
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LD D,A
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RET
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;
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; CONVERT LOW NIBBLE OF A TO ASCII HEX
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;
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HEXCONV:
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AND 0FH ;LOW NIBBLE ONLY
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ADD A,90H
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DAA
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ADC A,40H
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DAA
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RET
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;
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ERROR:
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LD DE,STR_ERR ; POINT TO ERROR STRING
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CALL PRTSTR ; PRINT IT
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HALT ; HALT
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;
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STR_LOAD .DB "\r\nLoading",0
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STR_DONE .DB "\r\n",0
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STR_ERR .DB " Read Error!",0
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;
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.ORG $ - $8000
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;
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.FILL (SECTOR_SIZE) - $ - 2
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.DW $AA55
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;
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.FILL ((PREFIX_SIZE - BLOCK_SIZE) - $),00H
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PR_SIG .DW $A55A ; SIGNATURE GOES HERE
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;
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PR_PLATFORM .DB PLATFORM
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PR_DEVICE .DB 0
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PR_FORMATTER .DB 0,0,0,0,0,0,0,0
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PR_DRIVE .DB 0
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PR_LOG_UNIT .DW 0
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;
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.FILL ((PREFIX_SIZE - METADATA_SIZE) - $),00H
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.DB 0 ; write protect boolean
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.DW 0 ; starting update number
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.DB RMJ,RMN,RUP,RTP
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.DB "Unlabeled Drive ","$"
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.DW 0 ; PTR TO LOCATION TO STORE DISKBOOT & BOOTDRIVE (SEE CNFGDATA)
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.DW CPM_LOC ; CCP START
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.DW CPM_END ; END OF CBIOS
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.DW CPM_ENT ; COLD BOOT LOCATION
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.END
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