OSDev.org

When a call to sti or cli is made, which device is actually effected? Does this tell the CPU to stop servicing interrupts, or does the CPU continue, but the PIC stops.

And another thing, where are the ports which we use with inb and outb, I mean physically. Are they on the motherboard? Or are they logical?

I just want to know exactly what my code is doing to the computer

those ports are only logical addresses with I/O devices. they should *not* be mixed with COM1, parallel or usb ports... for instance, port 220 used to be the main port of the soundblaster card ... this just means an outb(0x220,'x') sends 'x' out of the CPU to the register of the soundblaster that has I/O address 0x220 ... nothing more ... nothing less