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 Robotics / RCX / legOS / 264
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Subject: 
RE: signals / legOS internals
Newsgroups: 
lugnet.robotics.rcx.legos
Date: 
Wed, 23 Jun 1999 12:14:15 GMT
Viewed: 
970 times
  
Since it sounds like it might matter to you, I should point out that the
interrupt situation on the RCX is a bit more complicated than the H8 manual
makes it out to be.  Interrupt vectors are in ROM, but the ROM does a
dispatch to interrupt vectors in RAM.  The stack therefore has a bit more
on it than the H8 manual might suggest due to the fluff added by the
dispatch routine.  Details are on the RCX Internals web pages and in the
LegOS sources, but of course feel free to ask for a description if you'd
rather not hunt around.

Not to put too fine a point on it, and I hope Kekoa agrees, but the "fluff"
is the reason why replacement firmware works in the first place. Without
the ROM vectors being dispatched through RAM pointers that are initialized
by the ROM and then (possibly) overwritten by the replacement firmware, there
would be no possibility of doing what we are doing.

Thanks TLG (or the folks that did the firmware)

Cheers,

Ralph Hempel - P.Eng

------------------------------------------------------
Outside of a dog, a book is a man's best friend.
Indside of a dog, it's too dark to read...
------------------------------------------------------
Reply to:      rhempel at bmts dot com
------------------------------------------------------



Message is in Reply To:
  Re: signals / legOS internals
 
(...) Since it sounds like it might matter to you, I should point out that the interrupt situation on the RCX is a bit more complicated than the H8 manual makes it out to be. Interrupt vectors are in ROM, but the ROM does a dispatch to interrupt (...) (25 years ago, 23-Jun-99, to lugnet.robotics.rcx.legos)

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