mirror of
https://github.com/wwarthen/RomWBW.git
synced 2026-02-06 14:11:48 -06:00
bb70c36b36
The QPM portion of the build has been updated to dynamically combine the current CBIOS with the static QPM CCP and BDOS binaries. This will keep the QPM system image up to date and avoid HBIOS version mismatch warnings.
272 lines
7.2 KiB
NASM
272 lines
7.2 KiB
NASM
;===============================================================================
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; LOADER.ASM
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;
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; BOOTLOADER FOR ROMWBW DISK OPERATING SYSTEMS.
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;
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; CP/M DISK FORMATS ALLOW FOR RESERVED TRACKS THAT CONTAIN AN IMAGE OF THE
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; OPERATING SYSTEM TO BE LOADED WHEN THE DISK IS BOOTED. THE OPERATING SYSTEM
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; IMAGE ITSELF IS NORMALLY PREFIXED BY A 1-N SECTORS CONTAINING OS BOOTSTRAP
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; CODE AND DISK METADATA.
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;
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; THE RETROBREW COMPUTING GROUP HAS BEEN USING A CONVENTION OF PREFIXING THE
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; OS IMAGE WITH 3 SECTORS (512 BYTES X 3 FOR A TOTAL OF 1536 BYTES):
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;
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; SECTOR 1: IBM-PC STYLE BOOT BLOCK CONTAINING BOOTSTRAP,
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; PARTITION TABLE, AND BOOT SIGNATURE
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; SECTOR 2: RESERVED
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; SECTOR 3: METADATA
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;
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; THE HARDWARE BIOS IS EXPECTED TO READ AND LOAD THE FIRST TWO SECTORS FROM THE
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; DISK TO MEMORY ADDRESS $8000 AND JUMP TO THAT LOCATION TO BEGIN THE BOOT
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; PROCESS. THE BIOS IS EXPECTED TO VERIFY THAT A STANDARD BOOT SIGNATURE
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; OF $55, $AA IS PRESENT AT OFFSET $1FE-$1FF. IF THE SIGNATURE IS NOT FOUND,
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; THE BIOS SHOULD ASSUME THE DISK HAS NOT BEEN PROPERLY INITIALIZED AND SHOULD
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; NOT JUMP TO THE LOAD ADDRESS.
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;
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;===============================================================================
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;
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#INCLUDE "../ver.inc"
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;
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SYS_ENT .EQU $E600 ; SYSTEM (OS) ENTRY POINT ADDRESS
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SYS_LOC .EQU $D000 ; STARTING ADDRESS TO LOAD SYSTEM IMAGE
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SYS_END .EQU $FE00 ; ENDING ADDRESS OF SYSTEM IMAGE
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;
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SEC_SIZE .EQU 512 ; DISK SECTOR SIZE
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BLK_SIZE .EQU 128 ; OS BLOCK/RECORD SIZE
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;
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PREFIX_SIZE .EQU (SEC_SIZE * 3) ; 3 SECTORS
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;
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META_SIZE .EQU 32 ; SEE BELOW
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META_LOC .EQU (PREFIX_SIZE - META_SIZE)
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;
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PT_LOC .EQU $1BE
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PT_SIZ .EQU $40
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;
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;-------------------------------------------------------------------------------
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; SECTOR 1
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;
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; THIS SECTOR FOLLOWS THE CONVENTIONS OF AN IBM-PC MBR CONTAINING THE OS
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; BOOTSTRAP CODE, PARTITION TABLE, AND BOOT SIGNATURE
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;
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;----------------------------------------------------------------------------
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;
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; THE FOLLOWING BOOTSTRAP CODE IS BUILT TO ASSUME IT WILL BE EXECUTED AT A STARTING
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; ADDRESS OF $8000. THIS CODE IS *ONLY* FOR UNA. THE ROMWBW ROM BOOTLOADER
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; USES THE METADATA TO LOAD THE OS DIRECTLY.
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;
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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 SYS_ENT ; GO TO SYSTEM
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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 $0F ;LOW NIBBLE ONLY
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ADD A,$90
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DAA
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ADC A,$40
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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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; DATA
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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 ; BACK TO ABSOLUTE ADDRESS
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;
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.FILL PT_LOC - $,0 ; FILL TO START OF PARTITION TABLE
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;
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; STANDARD IBM-PC PARTITION TABLE. ALTHOUGH A
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; PARTITION TABLE IS NOT RELEVANT FOR A FLOPPY DISK, IT DOES NO HARM.
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; THE CONTENTS OF THE PARTITION TABLE CAN BE MANAGED BY FDISK80.
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;
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; BELOW WE ALLOW FOR 32 SLICES OF ROMWBW CP/M FILESYSTEMS
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; FOLLOWED BY A FAT16 PARTITION. THE SLICES FOLLOW THE ORIGINAL
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; HD512 ROMWBW FORMAT. IF THE DISK IS USING HD1K, A SEPARATE
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; PARTITION TABLE WILL BE IN PLACE AND RENDER THIS PARTITION TABLE
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; IRRELEVANT.
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;
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; THE CYL/SEC FIELDS ENCODE CYLINDER AND SECTOR AS:
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; CCCCCCCC:CCSSSSSS
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; 76543210:98543210
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;
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PART0:
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.DB 0 ; ACTIVE IF $80
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.DB 0 ; CHS START ADDRESS (HEAD)
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.DW 0 ; CHS START ADDRESS (CYL/SEC)
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.DB 0 ; PART TYPE ID
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.DB 0 ; CHS LAST ADDRESS (HEAD)
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.DW 0 ; CHS LAST ADDRESS (CYL/SEC)
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.DW 0,0 ; LBA FIRST (DWORD)
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.DW 0,0 ; LBA COUNT (DWORD)
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PART1:
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.DB 0 ; ACTIVE IF $80
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.DB 0 ; CHS START ADDRESS (HEAD)
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.DW %1111111111000001 ; CHS START ADDRESS (CYL/SEC)
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.DB 6 ; PART TYPE ID
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.DB 15 ; CHS LAST ADDRESS (HEAD)
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.DW %1111111111010000 ; CHS LAST ADDRESS (CYL/SEC)
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.DW $4000,$0010 ; LBA FIRST (DWORD)
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.DW $0000,$000C ; LBA COUNT (DWORD)
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PART2:
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.DB 0 ; ACTIVE IF $80
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.DB 0 ; CHS START ADDRESS (HEAD)
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.DW 0 ; CHS START ADDRESS (CYL/SEC)
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.DB 0 ; PART TYPE ID
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.DB 0 ; CHS LAST ADDRESS (HEAD)
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.DW 0 ; CHS LAST ADDRESS (CYL/SEC)
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.DW 0,0 ; LBA FIRST (DWORD)
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.DW 0,0 ; LBA COUNT (DWORD)
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PART3:
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.DB 0 ; ACTIVE IF $80
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.DB 0 ; CHS START ADDRESS (HEAD)
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.DW 0 ; CHS START ADDRESS (CYL/SEC)
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.DB 0 ; PART TYPE ID
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.DB 0 ; CHS LAST ADDRESS (HEAD)
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.DW 0 ; CHS LAST ADDRESS (CYL/SEC)
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.DW 0,0 ; LBA FIRST (DWORD)
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.DW 0,0 ; LBA COUNT (DWORD)
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;
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; THE END OF THE FIRST SECTOR MUST CONTAIN THE TWO BYTE BOOT SIGNATURE.
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;
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BOOTSIG .DB $55,$AA ; STANDARD BOOT SIGNATURE
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;
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;-------------------------------------------------------------------------------
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; SECTOR 2
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;
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; THIS SECTOR HAS NOT BEEN DEFINED AND IS RESERVED.
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;
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;----------------------------------------------------------------------------
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;
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.FILL SEC_SIZE,0 ; JUST FILL SECTOR WITH ZEROES
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;
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;-------------------------------------------------------------------------------
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; SECTOR 3
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;
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; OS AND DISK METADATA
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;
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;----------------------------------------------------------------------------
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;
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.FILL (BLK_SIZE * 3),0 ; FIRST 384 BYTES ARE NOT YET DEFINED
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;
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; THE FOLLOWING TWO BYTES ARE AN ADDITIONAL SIGNATURE THAT IS VERIFIED BY
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; SOME HARDWARE BIOSES.
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;
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PR_SIG .DB $5A,$A5 ; SIGNATURE GOES HERE
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;
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.FILL (META_LOC - $),0
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;
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; METADATA
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;
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PR_WP .DB 0 ; (1) WRITE PROTECT BOOLEAN
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PR_UPDSEQ .DW 0 ; (2) PREFIX UPDATE SEQUENCE NUMBER (DEPRECATED?)
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PR_VER .DB RMJ,RMN,RUP,RTP ; (4) OS BUILD VERSION
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PR_LABEL .DB "Unlabeled$$$$$$$","$" ; (17) DISK LABEL (EXACTLY 16 BYTES!!!)
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.DW 0 ; (2) DEPRECATED
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PR_LDLOC .DW SYS_LOC ; (2) ADDRESS TO START LOADING SYSTEM
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PR_LDEND .DW SYS_END ; (2) ADDRESS TO STOP LOADING SYSTEM
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PR_ENTRY .DW SYS_ENT ; (2) ADDRESS TO ENTER SYSTEM (OS)
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;
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#IF (META_SIZE != ($ - META_LOC))
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.ECHO "META_SIZE VALUE IS WRONG!!!\r\n"
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!!!
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#ENDIF
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;
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#IF ($ != PREFIX_SIZE)
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.ECHO "LOADER PREFIX IS WRONG SIZE!!!\r\n"
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!!!
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#ENDIF
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;
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.END
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