5/9/73  - JONL -

ERRORS GENERATED BY THE DISPLAY SLAVE ARE NOW CORRECTABLE, FAIL-ACT 
TYPE.  REMINDER:  IF THE FAIL-ACT INTERRUPT HANDLER RETURNS A NON-NULL
LIST, THEN THE CAR OF THAT LIST IS EVAL'D AND THE RESULTANT RETURNED
AS THE VALUE OF THE FORM WHICH LOST;  THE SYSTEM-SUPPLIED FAIL-ACT 
HANDLER IS A BREAK LOOP, AND IF ONE DESIRES TO PROCEED (ACCEPTING AN
OUTPUT VALUE OF T) HE CAN TYPE
(RETURN '(T))
TYPING <ALT-MODE>P<SPACE>   IS THE SAME AS RETURNING NIL, WHICH CAUSES
THE ERROR HANDLER TO GO THE ROUTE OF ALL UNCORRECTED ERRORS.


THERE IS A MANUAL FOR THE MULTICS VERSION OF MACLISP IN THE 
PREPARATION.  IT MAY PROVE TO BE OF MUCH USE EVEN TO THE PDP10 
MACLISP USER.


LISP WILL NOW ACCEPT A COMMAND LINE FROM DDT, IN THE FASHION OF THE
HACTRN COMMAND LINE.  THE SIGNIFICANCE OF THIS LINE FOR LISP IS THAT
IT IS USED TO SPECIFY A FILE FOR INITIAL LOADING, JUST AS THE 
.LISP. (INIT) FILE IS USED.  THUS, THE FIRST S-EXPRESSION ON THE FILE
MUST BE A COMMENT, WHOSE ALTERNATING PAIRS GIVE ALLOCATION REQUESTS;
THE REMAINDER OF THE FILE MAY BE ANY S-EXPRESSIONS.  FOR EXAMPLE, IF
ONE HAS A FILE "INDEX LOADER" ON HIS DIRECTORY WHICH CONTAINS

(COMMENT CORE 70 FXS 5000 FLPDL 1)
(FASLOAD INDEX FASL COM)

THEN WHEN HE TYPES AT DDT
:LISP INDEX LOADER<CARRIAGE-RETURN>

HE WILL FIND HIMSELF WITH A 70-BLOCK LISP (WITH A LITTLE EXTRA FIXNUM
SPACE, AND A MINIMAL FLONUM PDL) WHICH HAS BEEN EMBELLISHED WITH THE 
LISP INDEXER.  THE COMMAND LINE IS ALLOWED TO BE ANY ITS FILE 
SPECIFICATION, WITH DEFAULTING ON THE DEVICE TO BE DSK, AND
DEFAULTING ON THE SNAME TO BE THAT SET BY HACTRN.
REMINDER: THE FIRST ITEM OF AN ALTERNATING PAIR IN THE
COMMENT FOR ALLOC IS SPELLED EXACTLY THE WAY ALLOC SPELLS IT WHEN IT
TYPES THE QUESTIONS AT YOU;  IF YOU WANT TO TRY IT, JUST TYPE "Y" TO
THE QUESTION "ALLOC?" AND NOTE THE KINDS OF SPACES THAT ARE ASKED 
ABOUT.