Assembly as a language

#	What	Why	Fix
1	bad syntax for EQU	Tried to make lenstars include the newline like $ - stars, 0xA. NASM doesn’t like that.	Just made a separate newline variable and kept lenstars simple.
2	Symbol not found for initialmessage	Typo! Sometimes wrote intitialmessage instead of initialmessage.	Fixed all the typos so everything matches.
3	Weird output like .shstrt after running	32-bit code on a 64-bit system got linked wrong.	Assembled with -f elf32 and linked with -m elf_i386.
4	No newline after stars, so terminal prompt mashed with stars	Forgot to print a newline after the stars.	Added a separate newline variable and printed it after the stars.
5	Tried to print newline by just changing ecx/edx without new int 0x80	Only the last values before the interrupt count, so the stars didn’t print.	Made a second sys_write call just for the newline.
6	Confused about why edx was needed for the newline	Thought maybe eax/ebx/ecx was enough.	Learned: edx always needs the length of bytes to write, even if it’s 1 char.
7	Tried times 10 db ‘*’ to include newline	times just fills everything with *, so newline never worked.	Either define newline separately, or manually put it as the last byte.
8	32-bit syscalls acting weird on modern 64-bit Linux	Because the environment defaults to 64-bit.	Always assemble for 32-bit and link as 32-bit, problem solved.
9	Segmentation fault when reading input	tried to read or write more bytes than reserved in .bss	either reserve enough space or track how many bytes were actually read

Bare metal programming in assembly

#	What	Why	Fix
1	bit 16	nasm doesn’t need the bit 16 declaration it throws an error	remove that line for bare metal programming in nasm
2	made the first section of the bootloader more than 512 bytes	times 512 - ($ - $$) db 0 & dw 0xaa55	times 510 - ($ - $$) db 0 & dw 0xaa55
3	program origin redefined	Multiple org directives in the file	Keep only one org per file (stage 1 vs stage 2 separate)
4	parser: instruction expected	Invalid instruction or comment not prefixed with ;	Fix typos or add ; for comments
5	org value must be a critical expression	org was not a numeric constant	Use org 0x7C00 or org 0x8000 only
6	invalid combination of opcode and operands	Far jump used incorrectly (jmp 0x0000:0x8000)	Use jmp far 0x0000:0x8000
7	byte data exceeds bounds	Bootloader size exceeded 512 bytes	reduce the code size
8	symbol loop_exit not defined	assembler failed before reaching the level	fix the size of the bootloader
9	symbol jump_stage2 not defined	assembler failed before reaching the level	fix the size of the bootloader
10	missing print label after a20_not_supported label	jmp a20_not_supported_print jumps to a non existant lable	_print label or use a single loop label for printing
11	SI inside loop	mov si,message is inside the print loop, so SI is reset each iteration,	SI separate from the print loop loop label