30 days, the first day of self-made operating system merk11
The self-made operating system is not only because of the experimental homework left by school teachers, but also to deepen their understanding of the details of the operating system.
I’ve worked hard to find some on GoogleA tutorial for novices to develop a simple operating system
The environment used is windows and the virtual environment is QEMU
Books:
Self made operating system in 30 days: People’s Posts and Telecommunications Press
Comparison of GitHub Chinese disk source code:
https://github.com/yourtion/30dayMakeOS
https://github.com/chenganglist/30dayMakeOS
Books PDF Online:
http://file.qijin.tech/ebooks/30 Day self-made operating system_ compressed. pdf
We sincerely thank the providers of the above resources for their help to the fledgling college animals
Notes:
Environment configuration:Binary editor (hex editor)
Vscode, WinHex, Notepad + + or other familiar editors can be used
Assembly instruction learning:
DB: it is the abbreviation of “define byte“, that is, the instruction to write 1 byte directly to the file.You can write strings directly with it
DB "hello,world"RESB: it’s an abbreviation of “reserve byte”. If you want to spare 10 bytes from the current address, you can write it as RESB 10, which means that we have reserved these 10 bytes (you can imagine that we have reserved 10 consecutive seats in the right seat train).
DW: similar to DB, it reads 2 bytes at a time
DD: similar to DB, it reads 4 bytes at a time
Dollar sign: here is a variable that can tell us the current number of bytes in this line
RESB 0x1fe-$Main source code (the part you can try to write):
; hello-os
; TAB=4
; Standard FAT12 format floppy code
DB 0xeb, 0x4e, 0x90
DB "MERK11" ; Boot sector name (8 bytes)
DW five hundred and twelve ; Size of each sector (512 bytes required)
DB one ; Cluster size (must be 1 sector)
DW one ; Fat start position (generally the first sector)
DB two ; Number of fat (must be 2)
DW two hundred and twenty-four ; Root directory size (usually 224 items)
DW two thousand eight hundred and eighty ; The disk size (must be 2880 sectors 1440 * 1024 / 512)
DB 0xf0 ; Disk type (must be 0xf0)
DW nine ; Length of fat (must be 9 sectors)
DW eighteen ; A track has several sectors (must be 18)
DW two ; Number of heads (must be 2)
DD 0 ; Partition not used, must be 0
DD two thousand eight hundred and eighty ; Rewrite disk size once
DB 0,0,0x29 ; Meaning unknown (fixed)
DD 0xffffffff ; (possibly) volume label number
DB "MERK-OS " ; Name of the disk (must be 11 bytes, not enough space)
DB "FAT12 " ; Disk format name (must be 8 bytes, not enough space)
RESB eighteen ; Free 18 bytes first
; Program subject
DB 0xb8, 0x00, 0x00, 0x8e, 0xd0, 0xbc, 0x00, 0x7c
DB 0x8e, 0xd8, 0x8e, 0xc0, 0xbe, 0x74, 0x7c, 0x8a
DB 0x04, 0x83, 0xc6, 0x01, 0x3c, 0x00, 0x74, 0x09
DB 0xb4, 0x0e, 0xbb, 0x0f, 0x00, 0xcd, 0x10, 0xeb
DB 0xee, 0xf4, 0xeb, 0xfd
; Information display section
DB 0x0a, 0x0a ; Wrap twice
DB "It is impossible to manufacture or imitate love."
DB 0x0a ; Line feed
DB 0
RESB 0x1fe-$ ; Fill in 0x00 until 0x001fe
DB 0x55, 0xaa
; Output outside the boot sector
DB 0xf0, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00
RESB 4600
DB 0xf0, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00
RESB 1469432