Digital PDFs

XX-C46FC-9B

May 1986

1 pages

Original

0.2MB

Document:	PDP11-GoingStrong
Order Number:	XX-C46FC-9B
Revision:
Pages:	1
Original Filename:	http://vintagecomputer.net/digital/PDP11-GoingStrong.pdf

OCR Text

PDP-11 STILL GOING STRONG

The article "PDP Family Lives On,"
Ouly, "Dateline DEC") failed to show
why the PDP-11 family still is going
strong. It's a simple price versus per
formance issue. The software costs and
relative system performance can be
strikingly different.
If we compare some typical soft
ware prices we find:
1. VAX BASIC costs twice as much as
RSX or RSTS BASIC for a UNIBUS
machine - five times as much as for a
Q-bus machine.
2. VAX FORI'RAN-77 costs twice as much
as RSX or RSTS BASIC for a UNIBUS
machine - five times as much as for a
Q-bus machine.
3. VAX PASCAL costs almost twice as
much as RSX or RSTS BASIC for a
UNIBUS machine - 4.5 times as much
as for a Q-bus machine.
If I were to buy three packages for
a small VAX versus a Q-bus PDP-11, I
would spend approximately $16,700 for
the VAX software, $9,000 for the UNIBUS
PDP-11 software, and only $3,600 for the
Q-bus PDP-11 software. Prices for soft
ware maintenance are similarly cheaper.
When DEC tells me that it will
upgrade me from a MICROPDP-11 to a
MlCROVAX for $18,000 (Fall 1986 DEC
direct Update), it doesn't mention the
$13,000 difference in software costs.
The other major difference in the
price/performance question is the
overhead that VMS puts on the CPU.
Although our 11n50 has more MIPS
than our 11/44, in actual use the 11/44
comes out a winner. As a case in point ,
our VAX system manager asks us not to
run KERMIT during the day because it
significantly degrades eve.ryone's re
sponse time when we're running termi
nal emulation at 1200 baud. If we do the
same thing on PDP-11 KERMIT, you can't
tell that it's running. For equivalent
systems and loads, our PDP-11s can sup
port approximately twice the
INTERACTIVE users as our 750, although

Address letters to the editor to DEC

PROFESSIONAL magazine, P.O.

Box 503, Spring House, P A
194 77-0503. Letters should include
the writer's full name, address and
daytime telephone number. Letters
may be edited for purposes of
clarity or space.
the 750 has approximately 1.5 times the
MIPS of our 11/44.
Finally, there are many cases when
a PDP-11 has sufficient capacity for a
given job: A system often can be put to
gether for half the cost of an equivalent
VAX. That's why PDP-lls will be around
for a long time.
Frank R. Borger
Michael Reese Hospital
and Medical Center
Chicago, lliinois