Am 01.06.2016 um 18:59 schrieb Orchid Win7 v1:

>> For instance, in good old DOS, the sole entry point for all operating
>> system functions was INT 21h, with the AH register indicating which
>> function you intended to call.
> 
> That's essentially a direct call to the BIOS itself, isn't it? Or does
> MS-DOS actually interact with this somehow? (I realise that MS-DOS is a
> very thin "OS", if you can even call it that.)

No; the BIOS uses the same principle, but different interrupts.

BIOS-level disk I/O, for instance, uses INT 13h.


>> The x86 architecture also provides a mechanism known as a "call gate",
> 
> Yeah, I remember reading about that in the IA32 reference manual. I
> can't recall the details of how it works though.

Don't worry, the IA32 reference manuals recall the details pretty well ;)

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