On Thu, 19 Aug 2010, Anthony Liguori wrote: > On 08/19/2010 05:52 PM, malc wrote: > > > Yes, but the programming model was different. > > > > > > Look at the PIC compared to the lapic. The PIC is programmed via pio at a > > > fixed location. There is only one PIC and it interacts with the system > > > just > > > like all other devices. IOW, there is no reference to CPUState. > > > > > There are two PICs actually there's a cascade.. > > > > Technically speaking, originally there was just one and then more IRQs were > supported by cascading and reserving an IRQ line for supporting cascading. I > think you can technical cascade with any IRQ and have more than one slave but > the historic PC architecture only had one slave AFAIK.
One master + one slave = 2 PICs, i guess you've meant that originally there was no slave. [..snip..] -- mailto:av1...@comtv.ru
