bug report tahoe/ucb/2

make opcode an enum and cleanup a bunch of code so that
dbx is more useful (i.e. can step over part of a line of code); add
tempreg and has[[23]ops macros; force clr to check acc when writing dest

annotate cci derivation in sccsid

1.21 release; optimize aob inst; rearrange fp insts to overlap with integer insts

date and time created 86/03/02 15:30:42 by sam