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bug in TOPS-20 MacLisp terminal i/o
- To: bug-lisp at MIT-MC
- Subject: bug in TOPS-20 MacLisp terminal i/o
- From: Dave Touretzky at CMU-10A
- Date: Thu, 3 Jun 82 02:23:00 GMT
- Original-date: 2 June 1982 2223-EDT
The file <MACLISP>CSTEP.FASL on CMU-20C contains a CMU-modified version
of the Rich stepper. It demonstrates a bug in TOPS-20's i/o routine for
reading single characters from the terminal. To check out this bug you
should load the CMU programming environment described in the files
<MACLISP>LISP.INI and <MACLISP>COMMON.INI on CMU-20C.
One especially pertinent item: we run with (status linmode t).
After starting up a fresh Lisp, do the following:
(STEP T) ;load CMU's stepper
(PLUS 1 2)<space><cr> ;note that stepper isn't reading a space alone -- it
;needs a <cr> to terminate the read (bogus!)
START ;restart Lisp
(STEP T) ;try the stepper again
(PLUS 1 2)<space> ;now it can read <space> by itself!
^G ;quit to toplevel again
(STEP T) ;try the stepper one more time
(PLUS 1 2)<space><cr> ;now it can't read <space> !!!!
Clearly the terminal initialization done by START and that done
by ^G is not the same. I claim that only START does the initialization
-- Dave Touretzky