Re: The joy of FORTRAN

John Ames <commodorejohn@gmail.com> wrote in
news:20250227080310.0000604d@gmail.com:

On 26 Feb 2025 19:51:56 -0500
Rich Alderson <news@alderson.users.panix.com> wrote:
 

I wonder why DEC's 18-bit range weren't more popular; though I
think they had less consistency between members of the range than
DEC's other product families. 

 

I suspect that, in the computer market of the early '60s, they
ended up as the awkward middle child  ... 

 
Mr. Ames's suspicion is unfounded.  The 18 bit systems were neither
awkward nor unsuccessful.

 
I yield to those with firsthand knowledge - but I do wonder about their
eventual abandonment (per Wikipedia, the last -15 was produced in 1979,)
when both the -8 and -10 were supported well into the early '80s.

I acknowledge that I don't have first-hand knowledge of DEC's business
decisions,but I have some guesses. (I did have first-hand programming
experience with PDP-9, -15, -11 and -10 - but that's not the same thing.)

There were A LOT of PDP-8's out there, particularly embedded systems that
justified continued support and development.  However, new applications
would have favoured PDP-11's, particularly as LSI-11 single chip processors
became cheaper.  18-bit machines were much more expensive than the 12-bit
line and far fewer in number, so displacement by PDP-11's would have made
more sense.

The 36-bit line were more in the mainframe category where customers pay lots
and demand more.  However the cost of developing and supporting multiple
architectures eventually caught up with DEC. (A DEC salesman once told that
all local sales staff went out and got drunk when the demise of the -10 was
announced.  Apparently there were quite a few instatllations in the oil path
which is a very important industry around here.)