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346b18f8b4
...
7e41612687
Author | SHA1 | Date |
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Juhani Krekelä | 7e41612687 | |
Juhani Krekelä | 96dcfa48bb |
8
Makefile
8
Makefile
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@ -1,3 +1,5 @@
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FLOPPY = 1440
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.SUFFIXES:
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.SUFFIXES: .bin .asm
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@ -5,15 +7,15 @@ all: nor86.img
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nor86.img: bootsect.bin kernel.bin CC0 README.md
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rm -f $@
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mkdosfs -C $@ 1440
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mkdosfs -C $@ $(FLOPPY)
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rw -i bootsect.bin -o $@
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mcopy -i $@ CC0 ::
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mcopy -i $@ README.md ::
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mcopy -i $@ kernel.bin ::
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.asm.bin:
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nasm -fbin -o $@ $<
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nasm -MD $@.d -fbin -o $@ $<
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nasm -fbin -d F$(FLOPPY) -o $@ $<
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nasm -MD $@.d -d F$(FLOPPY) -fbin -o $@ $<
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clean:
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rm -f *.bin *.img *.bin.d
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@ -3,3 +3,11 @@ Nor86 operating system
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Nor86 is a real-mode operating system targeting IBM PC compatibles with 64K
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or more RAM. It is inspired by [EttinOS](https://ahti.space/git/crazyettin/EttinOS).
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Floppy sizes
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------------
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You can build either a 1440K or a 360K floppy image from Nor86 sources, the
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default being 1440K. To build a 360K floppy instead, run:
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make FLOPPY=360
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48
bootsect.asm
48
bootsect.asm
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@ -4,6 +4,7 @@ org 0x7c00
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jmp short _code
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nop
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%ifdef F1440
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; 1440K floppy
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; BPB
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oemidentifier db "nor86 "
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@ -20,6 +21,27 @@ heads dw 2
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hiddensectors dd 0
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totalsectorslarge dd 0
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%elifdef F360
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; 360K floppy
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; BPB
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oemidentifier db "nor86 "
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byterpersector dw 512
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sectorspercluster db 2
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reservedsectors dw 1
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fats db 2
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rootdirentries dw 112
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totalsectors dw 720
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mediadescription db 0xfd
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sectorsperfat dw 2
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sectorspertrack dw 9
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heads dw 2
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hiddensectors dd 0
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totalsectorslarge dd 0
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%else
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%error "No valid floppy format specified, specify -d F1440 or -d F360"
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%endif
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; EBPB
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drivenumber db 0 ; useless on-disk, used as a variable
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reserved db 0 ; winnt flags
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@ -45,6 +67,28 @@ _start:
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; Save bootdrive
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mov [drivenumber], dl
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select_os:
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mov ah, 0xe
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mov si, prompt
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.print:
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lodsb
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test al, al
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jz .end
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int 0x10
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jmp .print
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.end:
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xor ax, ax
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int 0x16
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cmp al, 'e'
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jne calc_constants
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mov si, ettinos_kernel_name
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mov di, kernel_name
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mov cx, 11
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rep movsb
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calc_constants:
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; Disk organization:
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; Reserved sectors (MBR)
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@ -288,9 +332,9 @@ chs:
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pop ax
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ret
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%include "hexprint.inc"
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prompt: db "Select OS. 'e' for EttinOS, any other key Nor86.", 0
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kernel_name: db "KERNEL BIN"
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ettinos_kernel_name: db "SYSTEM BIN"
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times 510-($-$$) db 0
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db 0x55, 0xaa
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