first commit

.gitignore

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+*.o
+*.img
+*.bin
+*~

LICENSE

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+BSD 3-Clause License
+
+Copyright (c) 2020, d0p1
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright notice,
+  this list of conditions and the following disclaimer in the documentation
+  and/or other materials provided with the distribution.
+
+* Neither the name of the copyright holder nor the names of its
+  contributors may be used to endorse or promote products derived from
+  this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Makefile

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+all: stupid.img
+
+stupid.img: floppy.bin kern.bin
+	cat $^ /dev/zero | dd of=$@ bs=512 count=2880
+
+floppy.bin: boot/floppy.s
+	nasm -fbin -o $@ $^
+
+kern.bin: kern/kernel.s
+	nasm -fbin -o $@ $^
+
+clean:
+	rm floppy.bin kern.bin
+
+fclean:
+	rm stupid.img
+
+re: fclean all
+
+.PHONY: all clean fclean re

README.md

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+# StupidOS
+
+16bit real mode Operating System in assembly
+

boot/floppy.s

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+	[ORG 0x7c00]
+	[BITS 16]
+
+	jmp short entry
+	nop
+
+	;; -----------------------------------------------------------
+	;; OEM & Bios Parameter Block
+	;; -----------------------------------------------------------
+	db "StupidOS"
+
+	dw 512 			; bytes per sector
+	db 1			; sector per cluster
+	dw 1			; reserved sector
+	db 2			; number of FATs
+	dw 224			; root entries
+	dw 2400			; total sector
+	db 0xF9			; media descriptor type
+	dw 7			; sectors per FAT
+	dw 15			; sectors per track
+	dw 2			; heads per cylinder
+	dd 0			; hidden sectors
+	dd 0			; total sector big
+	db 0			; drive number
+	db 0			; unused
+	db 0x29 		; drive signature (0x29 = floppy) 
+	dd 0x00000000		; serial number (ignore)
+	db 'STUPID DISK'	; volume label
+	db 'FAT12   '		; filesystem type
+	
+	;; -----------------------------------------------------------
+	;; Print string using bios interrupt
+	;; -----------------------------------------------------------
+boot_print:
+	pusha
+.loop:
+	lodsb
+	cmp al, 0
+	jz .end
+	mov ah, 0x0E		; bios print
+	mov bx, 0x07
+	int 0x10
+	jmp .loop
+.end:
+	popa
+	ret
+
+	;; -----------------------------------------------------------
+	;; Variables
+	;; -----------------------------------------------------------
+	copyright db "Copyright (c) d0p1", 13, 10, 0
+	err_disk_reset db "Error reseting disk..retry", 13, 10, 0
+
+	;; -----------------------------------------------------------
+	;; entry
+	;; -----------------------------------------------------------
+entry:
+	xor ax, ax
+	mov ds, ax
+
+	mov si, copyright
+	call boot_print
+reset_disk:
+	xor ah, ah
+	xor dl, dl
+	int 0x13
+	jnc .reset_disk_end
+	mov si, err_disk_reset
+	call boot_print
+	jmp reset_disk
+.reset_disk_end:
+	
+hang:
+	jmp hang
+	cli
+	hlt
+
+	times 510-($-$$) db 0
+	db 0x55
+	db 0xAA
+