[Gllug] Beagle Board

Andrew Farnsworth farnsaw at stonedoor.com
Tue Jan 13 13:43:54 UTC 2009

Vidar Hokstad wrote:
> On 12 Jan 2009, at 18:30, Peter Corlett wrote:
>> To do pre-emptive multitasking, all you need is some means of
>> generating a reasonably frequent and hopefully also regular interrupt.
> [..]
>> On interrupt, the CPU can then push registers onto the stack, move the
>> stack pointer to a different location, and pop the registers to
>> restore the state for that process. Hey presto, a pre-emptive task
>> switch.
> I was about to complain about that claim the PC lacked hardware  
> support for it too, but you did a much better job.

Well, I stand (ok, sit) corrected.  Up until now, my understanding had 
been exactly what I had stated.  I knew that some type of regular 
hardware interrupt was required for Preemptive multitasking to work and 
I thought it had been absent until the era of the 68020/30 chips which 
would have been about the time the 386 came out.  I knew that non-pc 
computers supported the hardware interrupts and PMT but I it is news to 
me that early PCs had this as well.

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