BIOS system calls

Serial

System call	Parameters	Description
SYS_PUTC	A - character	Print character on string
SYS_GETC		Input serial char, and place in A
SYS_GETCW		Wait until a serial char is available, and place it in A
SYS_PRINT	HL - string	Print a null-terminated string
SYS_INPUT	A - max string size, HL - buffer pointer	Read an input from the user
SYS_PRINTHEX	A - number of digits, DE - value	Print the value in hexadecimal format

Arithmetic

System call	Parameters	Description
SYS_COMPARE_16	DE, HL - values	Compare values in DE, HL - set flags accordingly

Strings

System call	Parameters	Return value	Description
SYS_STRFIND	A - needle, HL - haystack	HL - position, Carry=0 - found	Find a char in a string