Two more System 78 differences that you should know about.

[Daniel L. Weinreb <dlw at MIT-AI>]

In the recently-released System 78:

Only one process is permitted to be running the compiler at a time.  It
used to be that if you tried to run the compiler in two processes at
once, you got strange and mysterious errors; now the second process
waits for the first one to finish.  It waits in process state "Lock",
which you may see in the who-line if this happens to you.  This means
that if a process goes into the error handler during compilation and
you then try to run the compiler in a second process without aborting
out of the error handler in the first process, the second process
will wait.

The initial value of READTABLE is now a copy of SI:INITIAL-READTABLE.
You should never change the contents of SI:INITIAL-READTABLE; this
should be left pristene so that other programs can make copies of it in
order to get a fresh readtable.  Change READTABLE instead.  (Some people
who have reader macros to cause font change sequences to be ignored may
be affected by this change.)