# -------------------------------------------------------------------
# 68K                                   (c) Copyright 1996 Nat! & KKP
# -------------------------------------------------------------------
# These are some of the results/guesses that Klaus and Nat! found
# out about the Jaguar with a few helpful hints by other people, 
# who'd prefer to remain anonymous. 
#
# Since we are not under NDA or anything from Atari we feel free to 
# give this to you for educational purposes only.
#
# Please note, that this is not official documentation from Atari
# or derived work thereof (both of us have never seen the Atari docs)
# and Atari isn't connected with this in any way.
#
# Please use this informationphile as a starting point for your own
# exploration and not as a reference. If you find anything innacurate,
# missing, needing more explanation etc. by all means please write
# to us:
#	  nat@zumdick.rhein-main.de
# or
#	  kkp@gamma.dou.dk
#
# If you could do us a small favor, don't use this information for
# those lame flamewars on r.g.v.a or the mailing list.
#
# HTML soon ?
# -------------------------------------------------------------------
# $Id: 68k.txt,v 1.1 1996/01/28 20:23:18 nat Exp $
# -------------------------------------------------------------------

Preface:
   There isn't much we need to tell you about the 68K. First you 
   already know the chip since ten years probably, and secondly 
   there are enough reference books available in case your memory
   is failing you. Let's just look at the way the processor is bound
   into the system and somethings to watch out.


IRQs:
=-=-=

      IPL         Name           Vector            Control
   ---------+---------------+---------------+---------------
    Level 2    VBLANK IRQ         $100         INT1 bit #0 

   A typical way to install a VBL handler for the 68000 would be something
   like this, you gotta supply "last_line" and "handler"

   V_LEVEL0 = $100
   VI       = $F004E
   INT1     = $F00E0
   INT2     = $F00E2
   
         move.w   #$2700,sr         ;; no IRQs please
         move.l   #handler,$100     ;; install our routine

         move.w   #last_line,$F004E ;; scanline where IRQ should occur
                                    ;; should be 'odd' BTW
         move.w   #1,INT1           ;; enable LEVEL 0 IRQ
         move.w   #$2100,sr         ;; enable all IRQs on the 68K
