This directory consists of runtime support routines for Russell on
a Motorola 68K series processor.  Hopefully these routines are a little
more portable than the VAX version.  Nonetheless, they currently
only run on a 68020.

Remarks:

1.  Everything in this directory assumes we are using an approximate
  marking algorithm in the garbage collector.  Every attempt is made
  to reduce the probability of a non-pointer getting misidentified as
  a pointer, but we do not make any guarantees to this effect.  The
  garbage collector must be able to accomodate such misinterpretations,
  though they can clearly result in wasted space.

2.  Unlike the VAX, the 68000 does not easily allow Russell procedure
  calls to be compatible with C.  Thus we generate interface routines.

3.  The following register assignments are used:
	    a7  -  stack pointer
	    a6  -  frame pointer
	    a5  -  a.r. pointer (left unchanged in NO_SL calls)
	    a4  -  pointer to global activation record

    Occasionally bits and pieces of VAX specific code were left
  around (inside appropriate ifdefs).  These assume that ap
  takes the place of a5.

4.  The first register allocated by the SUN C compiler to a pointer
  register variable is a5.  The first one allocated to a non-pointer
  register variable is d7.  Subsequent register variables are
  assigned to decreasing register numbers.
