🚀 go-pugleaf

If you extend the switching stacks idea a little further, you can implement
a multi-tasking OS kernal rather easily.

Do not try this at home:   ;)

Intercept the timer interrupt to count the number of time clicks the current
process has been running for.  When it reaches a terminal count, generate
an interrupt to call the dispatcher.

The dispatcher's job is to remove the process in the run queue and place
it in ascending order (by priority) in the ready queue.  It then takes the
first item from the ready queue (==the highest priority) and places it in the
run queue.  THEN (here's the tricky part) it switches stack segments from the
one which belonged to the last running process to the stack segment of the
next process to run.

When all of the interrupts unwind, the point in the new process where it
was interrupt gets popped off into the registers, and the new process starts
executing where it left off.

= = = = = = = = 
Off course, the only tricky part is loading the .EXE's from disk and 
initializing the stacks to point to their entry point.

= = = = = = = =
If you'd like to discuss this further, contact me offline...

Cheers,
Q - the "Q"uestor for knowledge (, a degree, etc.)

lsalomo@hubcap.clemson.edu
ibmman@prism.clemson.edu
ibmman@clemson.clemson.edu
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