🚀 go-pugleaf

In article <6840@ucdavis.ucdavis.edu> shih@iris.ucdavis.edu (Alan S. Shih) writes:
>
>   Are there anybody who know how to switch interrupt table from real
>   mode to protected mode? I know that interrupt table is only
>   relative with IDT, however, is the memory address for there bios
>   routine still the same? 
>   I am trying to write a OS for my 386 which hopefully will utilize
>   my vga + multitasking.  Any advise is appreciated!
>

Alan,
    in protected mode the Interrupt table becomes a table of gates,
which are 8 byte descriptors which discribe where your interrupt routine
is, who my use it (the privalage level needed to access it) how it is
accessed (task, trap, interrupt)
	task - a seperate task is envoked suspend the current task
	trap - interrupt flag is left alone
	interrupt - interrupt flag cleared ( for device IRQ's)
trying to use your bios in protected mode is going to be tricky
most bios'es are not designed to be run in protected mode, the segment
selectors are all different (you do know about segment selectors 
don't you) unless you have a PS/2 with ABIOS. I am setting up a small
protected mode system and ALL i/o i need to write myself a suggestion
is to write a register dump routine as soon as possible so you 
know where your program is hanging (i have one patched into ALL INT's
for now ;-) I hope this helps

			Jay
-- 
		Jay B. Harlow	<harlow@plains.nodak.edu>
	uunet!plains!harlow (UUCP)	harlow@plains (Bitnet)

Of course the above is personal opinion, And has no bearing on reality...