Finally understand location 7 (incremented at 60Hz)
setting it to -1 causes clock interrupt every jiffy
Improve comments in dsktrans
Clarify cnop/cskp usage in iread/iwrite code
iwrite and iread have common code
entry at iwrite save return address at iread
and overwrites return address to "skp" inst
entry at iread puts "nop" inst at iwrite
"xct iwrite" skips on write entry
source code is now in src/alt. All the files in src/sys and src/cmd
are only annotated versions of the files in scans/.
The build/Makefile has been updated so that it can build the
original PDP-7 Unix or the alternative version.
Phil has fixed the Graphics-2 code, so that there is no need to
have any #ifdef code in the original kernel.
phil