Re: Help me in BIOS writing
I'm not an expert.
Assembler is used for the large part, because of direct register manipulation, which keeps the code compact.
you'll need a general call which deciphers the request, does any housekeeping then transfers the request to more specific routines.
Establish guidelines to apply to all requests, ie; immediate data in specific registers, memory blocks specifically assigned, etc.
Determine what registers, memory blocks are altered by the routines, and what and where thier responses will be returned.
Determine what housekeeping is required prior to returning from calls.