R.I.P. Paul Penfield

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Doug White

Jul 21, 2021, 9:35:45 PMJul 21
MIT Professor Paul Penfield Jr. passed away late last month. Paul was
extremely active in the APL community in the 1960's & 70's, and championed
using it as an educational tool at MIT. It was used in several basic EE
courses, and I remember first being introduced to APL that way.

Paul developed an APL circuit analysis package named after his wife,
MARTHA. Unlike the canned circuit CAD programs popular today, it was a set
of functions for circuit analysis that allowed the user to synthesize as
well as analyze circuits with unparalled flexibility.

I worked at MIT Lincoln Laboratory for a number of years, where MARTHA was
extremely popular. Paul consulted with the Lab supporting the program.
Over time, various staff members (myself included) added a large number of
additional workspaces to MARTHA for various tasks.

In the late 1980's I was tasked with converting all of Lincoln's APL from
their mainframe to run on personal computers. I worked closely with Paul
on this, and was constantly amazed at his intellect and memory. The MARTHA
code was designed to run in a very small amount of RAM. There were no
comments, and Paul played all sorts of odd tricks to save a few bytes here
& there. I ran into an error once and called him, and (without having
worked much on the code for about a decade) he immediately told me to go to
a specific function, and change a number on line [7]. It turned out to be
a built in expiration date, originally set so far in the future that he
figured no one would still be using it.

Here is a link to his obituary, including info on a memorial service at the
end of August:


We are diminished...

Doug White
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