[comp.emacs] GNU EMACS For Prime Computer under PRIMOS?

hecker@fed1.prime.COM (Frank Hecker) (11/17/88)

I work for Prime Federal Operations in Rockville, Maryland.  I'm a
long-time user of Prime EMACS for the Prime 50 Series under PRIMOS,
and have also recently ported GNU Emacs to the Prime EXL Series
(80386-based UNIX System V systems).

In response to the query by Russ Rodriguez regarding GNU Emacs for
PRIMOS, I must confess that its wording somewhat confused me.  Did
the phrase "the version that came with the machine" refer to the
EMACS editor sold and supported by Prime?  If so, be aware that Prime
EMACS was not derived directly from the present GNU Emacs but rather
was one of the numerous Emacs clones created in imitation of the
original TECO-based Emacs.  (I believe Prime EMACS was introduced as
a product in 1982 or 1983.)  Prime EMACS is written in SPL (a
Prime-specific dialect of PL/I) rather than C, and as I recall the
original version was acquired by Prime from Software Arts, Inc.
(remember Visicalc?).

I am not aware of any version of GNU Emacs (18.52 or otherwise) that
has been ported to the Prime 50 Series under PRIMOS.  The potential
problems in doing so are as follows:

1) Changes would be required in the area of OS-dependent routines
similar in nature and extent to the changes required for VMS support.

2) Adequate performance would require using the -32ix option to the
Prime C compiler to generate instructions using the new IX mode
addressing (new since 1983, that is).  (IX mode for C basically gives
you adequate byte addressing; the earlier V mode used 16-bit word
addressing by default, with byte addressing requiring a 48-bit
pointer.)   The resulting code would only run on IX-mode systems (all
four-digit models except the 2250).  It would _not_ run on earlier
systems such as the 750.

3) Even after using IX mode, you would probably have to do extensive
performance tuning to deal with some of the peculiarities of the 50
Series virtual memory architecture and the PRIMOS shared library
system.  I used the original beta version of Prime EMACS and it was
quite slow, especially in terms of startup time.  The current version
is pretty well-tuned, but requires the use of some techniques that
are still not documented and supported for customer use.

If anyone is still interested in doing a port of GNU Emacs to PRIMOS
I will be glad to advise to the best of my ability, and am also
willing to supply a standard 1600-bpi tape in PRIMOS MAGSAV format
containing the current GNU Emacs version 18.52 distribution.  Please
respond via email to the above address or feel free to call me at
(301) 948-7010 x308.

Frank Hecker