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@ECHO OFF

IF NOT EXIST Z:\BIN MKDIR Z:\BIN

NASM Z:\SRC\BOOT.ASM     -o Z:\BIN\FLP144MB.BIN -f bin -O0
NASM Z:\SRC\IO.ASM       -o Z:\BIN\IO.SYS       -f bin -O0
NASM Z:\SRC\RMDOS.ASM    -o Z:\BIN\RMDOS.SYS    -f bin -O0
NASM Z:\SRC\COMMAND.ASM  -o Z:\BIN\COMMAND.COM  -f bin -O0

IF EXIST Z:\PEDOS1D0.IMG DEL Z:\PEDOS1D0.IMG

DD if=/dev/zero of=Z:\PEDOS1D0.IMG bs=512 count=2880
DD if=Z:\BIN\FLP144MB.BIN of=Z:\PEDOS1D0.IMG bs=512 count=1 seek=0

IMDISK -a -f Z:\PEDOS1D0.IMG -s 1440K -m A:

COPY Z:\BIN\IO.SYS       A:\IO.SYS
COPY Z:\BIN\RMDOS.SYS    A:\RMDOS.SYS
COPY Z:\BIN\COMMAND.COM  A:\COMMAND.COM

IMDISK -D -m A:

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BIOSSEG	EQU 07C0H	; where the PC-BIOS reads the boot-sector.
BOOTSEG	EQU 0AE0H	; the segment where the boot-sector is relocated.
LOADSEG	EQU 0050H	; where the real-mode DOS system is read. 

DOSSECCNT	EQU 2	; how many sectors IO.SYS + RMDOS.SYS occupy

	USE16

        JMP  SHORT BEGLDR
        NOP
BPBBEG:
	DB "PEDOS1.0"
BYPRSC:	DW 512
SCPRCL:	DB 1
RVSCCN:	DW 1
FATCNT:	DB 2
RDECNT:	DW 224
	DW 2880
	DB 0F0H
SCPRTR:	DW 9
SCPRFT:	DW 18
TRPRCY:	DW 2
	DD 0
	DD 0
	DW 0
	DB 41
	DD 0
	DB "           "
	DB "FAT12   "
BPBEND:

;
; This code sets all necessary segment
; registers to known values, and copies
; the boot-sector to a higher memory
; address. This boot-sector assumes a
; non-standard CS:IP, DS, and SS.
;
;
; Before Relocation:
;
; CS = ????
; DS = 07C0
; SS = 0AE0
; ES = 0AE0
; ---------
; IP = ????
;
;
; After Relocation:
;
; CS = 0AE0
; DS = 0AE0
; SS = 0AE0
; ES = 0050
; ---------
; IP = ????
; 

BEGLDR:
	MOV  AX, BOOTSEG
	MOV  ES, AX
	CLI			; clear maskable interrupts
	MOV  SS, AX
	MOV  SP, 1024
	STI			; restore interrupts
	PUSH WORD BIOSSEG
	POP  DS
	MOV  CX, 256
	XOR  SI, SI	; DS:SI should be 07C0:0
	XOR  DI, DI	; ES:DI should be 0AE0:0
	CLD
	REP  MOVSW

; DS:SI = 07C0:0 ... 07C0:1FE
; ES:DI = 0AE0:0 ... 0AE0:1FE

SAVSRS:
	PUSH ES   ; We no longer need ES, so
	POP  DS   ; DS now becomes ES (0AE0)
RSTCPU:
	PUSH BOOTSEG
	PUSH WORD CHKDSK
	RETF

;
; Next, this code will check that this
; disk is a valid System disk, and then
; load the following files:
;
; - IO.SYS
; - RMDOS.SYS
;
; from the disk to the following
; memory locations:
;
; IO      .SYS = 0050:0
; RMDOS   .SYS = 0050:0+LEN(IO.SYS)
;

CHKDSK:
	MOV  AX, WORD LOADSEG
	MOV  ES, AX
	MOV  AX, 19	; Starting LBA of Root-Dir Table.
	MOV  CX, 1	; We only need the first two entries.
	XOR  BX, BX	; Read the above exactly past the boot-sector.
	XOR  DX, DX
	ADC  DX, 0	; Correct the LBA before reading.
	CALL REDSEC
FNDDOS:
	XOR  DI, DI		; ES:DI
	MOV  SI, WORD SYSFLE	; DS:SI
	MOV  CX, 11
	REPE CMPSB
	JE   LODDOS
DSKERR:
	MOV  SI, WORD ERRMSG
	JMP  PRNSTR
LODDOS:
	MOV  AH, 14
	MOV  AL, '!'
	INT  16
	JMP  SHORT $

;
; Finally, this code will cause a CS:IP
; reset via far-jumping to the DOS system
; entry point.
;

RUNDOS:
        PUSH 0050H
        PUSH 0000H
	RETF

;
; PRNSTR: Copy the char-string specified by SI
;         into video memory, and await a system
;         reset.
;
; IN: DS:SI = addr of char-string
;

PRNSTR:
	LODSB
	OR   AL, 0		; Strings must be null-terminated.
	JZ   SHORT SR2RET
	MOV  AH, 14
	MOV  BX, 0
	INT  16		; 10H
	JMP  SHORT PRNSTR
SR2RET:
	XOR  AX, AX
	INT  22		; After the error message has been
	INT  25		; displayed, await a system reset.
;
;
; REDSEC: Read the specified sectors into memory
;         at logical address ES:BX.
; IN:
;
; DX:AX	= head, track, sector value
; CX	= sector count
;

REDSEC:
	PUSHA
        DIV  WORD [SCPRTR]
        MOV  CX, DX
        INC  CX
        XOR  DX, DX
        DIV  WORD [TRPRCY]
        MOV  CH, AL
        SHL  AH, 6
        OR   CL, AH
        MOV  DH, DL
        MOV  DL, 0	; This binary is only for floppy disks.
        MOV  AX, 201H
        INT  19		; 13H
        JNC  SHORT NXTSEC
        JMP  DSKERR
NXTSEC:
        POPA
	DEC  CX
	JZ   SHORT SR1RET
	ADD  BX, WORD [BYPRSC]
	ADD  AX, 1
	ADC  DX, 0
	JMP  SHORT REDSEC
SR1RET:
        RET

; error message
ERRMSG:	DB "Non-System disk or disk error... Replace and try again when ready."
	DB 0
DOSFLE:	DB "RMDOS   SYS" ; The real-mode kernel component to PE-DOS.
SYSFLE:	DB "IO      SYS" ; I/O system. 
	

	TIMES 510 - ($ - $$) DB 0

        DW 0AA55H	; End of Boot Sector.

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	USE16
	ORG  500H

	MOV  AH, 14 ; 0Eh
	MOV  AL, 'I'
	INT  16		; 10H
	MOV  AL, 'O'
	INT  16		; 10H
	MOV  AL, '.'
	INT  16		; 10H
	MOV  AL, 'S'
	INT  16		; 10H
	MOV  AL, 'Y'
	INT  16		; 10H
	MOV  AL, 'S'
	INT  16		; 10H

JMP SHORT $

TIMES 2048 - ($ - $$) DB 0

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	USE16
	ORG  7C00H
	
FLEHDR:
	DW "MZ"
	DW 0
	DW 0
	DW 0
	DW 0
	DW 0
	DW 0
	DW 0
	DW 0
	DW 0
	DW 0
	DW 0
	DW 0
	DW 0
HDREND:
KRNBEG:
	JMP  SHORT $

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CHKDSK:
	PUSH LOADSEG
	POP  ES
	MOV  AX, 19	; Starting LBA after Root-Dir Table.
	MOV  CX, 1
	XOR  BX, BX	; Read the above exactly past the boot-sector.
	XOR  DX, DX
	ADC  DX, 0	; Correct the LBA before reading.
	CALL REDSEC
	XOR  DI, DI
	MOV  SI, WORD SYSFLE ; "IO      SYS"
	MOV  CX, 11
	REPE CMPSB
	JNE  DSKERR
	ADD  DI, 32      ; next entry, right?
	MOV  SI, WORD DOSFLE ; "RMDOS   SYS"
	MOV  CX, 11
	REPE CMPSB
	JE   LODDOS ; skip error code if no error, right?
DSKERR:
	MOV  SI, WORD MSG000
	JMP  PRNSTR
LODDOS:
	MOV  AH, 14 ; dummy code below.
	MOV  AL, '!'
	INT  16
	JMP  SHORT $