Date:	Fri, 23 Dec 1994 19:51:18 +0900
From:	Stephen Turnbull <turnbull AT shako DOT sk DOT tsukuba DOT ac DOT jp>
To:	wrh AT placer1 DOT wimsey DOT com
Cc:	djgpp AT sun DOT soe DOT clarkson DOT edu
Subject:	Math Emulator

   I am contemplating the purchase of a Notebook PC *without*
   a math co-processor.  How well does the emulator supplied
   with 1.11m5 work?  What kind of performance hit as far as
   speed of compilation, memory problems or other unpleasantness
   is lurking out there?

   Concerned and Confused, 
   William

Dear Concerned and Confused:

Quick and dirty benchmark:  Three beta versions of Ghostscript, about
215 objects, 4MB unstripped, 800-950KB stripped executables.
            System #1        System #2
Beta #1     2 hr 45 min*     16 hr*
Beta #2     2 hr 10 min      9 hr 13 min
Beta #3     2 hr 25 min      9 hr 32 min

System #1 is a not-memory-optimized AMI 486DX/50MHz EISA system with
16MB RAM and a couple hundred MB free HD, running DESQview/X and IBM
DOS/V 5.0, with multitasking, including remote windows to my mail
machine and Mathematica, a local Emacs, and local TeX running much of
the time.

System #2 is an IBM 330cs ThinkPad with 12MB RAM, 486SX/50MHz, stock
EMU387, about 100MB free HD, running IBM DOS/V 5.0 and QEMM 7.04 no
DPMI.

The * means that for reasons I couldn't track down the build had to be
restarted four or five times.  System #2's time is extremely
unreliable, it was interrupted overnight and I'm not guessing at how
much time was lost.  The times are pretty approximate; I didn't use
timers; I subtracted earliest object time from executable time.

Conclusion:  serious performance hit.  I can't speak to the accuracy,
but it's better than a Pentium....

I don't really understand why there's such a large performance hit,
since most compilation is digital in nature, but it may be that the
disk is fairly slow (28ms vs 14ms on the office machine).  It might be
possible to speed things up by optimizing the use of memory, but I
only do such large things at home once in a while, 'cause I'm a beta
tester....  Overnight is fine for this usage.

Another thing which is somewhat unrelated: PCMCIA services use up a
*lot* (essentially all) of high memory on this system.  That means the
biggest DESQview/X window I've managed with PCMCIA services installed
is 325KB, not enough to run GCC, let alone make.

Recommendations:  get as much memory as the thing will take, and get
ready for a lot of multiboot configurations.

On the up-side, with DV/X installed, the thing is a fine X terminal,
although the resolution on GIFs leaves a lot to be desired.

Signed,
Dear Abby

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