Logicon "Computer" Desktop Calculator
The first operating prototype of the Logicon Inc.'s LOGICON Computer, Spring, 1965
Image Courtesy Dr. Norman M. Martin
The photo above shows the first operating prototype of the LOGICON Computer
taken at Logicon, Inc.'s offices in Redondo Beach, California sometime
around the spring of 1965. The term "Computer" in the name implies that it
is more than just a calculator, and in truth, the machine actually is, but
in general practice, the machine's interface is much more calculator like,
putting it in the category of programmable calculator, though it does have
the ability to be programmed in the core CPU's machine language for more
The LOGICON Computer (it was generally referred to as "the computer") was a
sophisticated programmable desktop electronic calculator designed and built for
in-house engineering calculations by Logicon, Inc. Logicon was founded
in April, 1961, in Redondo Beach, California, by eight individuals who
funded its initial operations, with the charter to develop
advanced computing equipment, but as it turned out, most of their work
ended up being related to computing systems development and integration
for the US Defense Department, National Security Agency, and other
governmental agencies, as well as private business.
The company was immediately profitable, and made its first public stock
offering in October, 1969. The company thrived, landing many lucrative
military and government contracts over the years. Logicon, Inc.
was acquired in August, 1997, by Northrup Grumman, the aeronautical firm
famous for developing a lot of the space systems and vehicles used by
NASA in the US space program, various military aircraft, and tactical and
The LOGICON Computer was a five-function calculator, providing the usual
addition, subtraction, multiplication, and division, along with
automatic square root. The prototype operated on a ten digit
mantissa with floating decimal point, and a power-of-ten exponent from
-49 to +50. It provided a substantial number of memory registers for
storage of numbers, although the actual number of registers is currently
It not known what type of circuitry was used for
the logic of the machine, but given that Logicon's business centered around
the computing, defense and aerospace industries, all of which were among
the first to use early Integrated Circuits, as well as the fact that the
machine appears quite small for its capabilities, it seems plausible that the
machine's logic may have been created using early bipolar integrated
circuits. The machine's architecture was very computer-like, with two
microcode-driven engines that ran the machine. One microcode engine took
care of the basic calculator user interface, e.g., managing the keyboard,
CRT display, and external I/O operations.
The display used a modified raster scan method, scanning the
characters vertically, a column at a time illuminating dots
that formed the digits and characters. Apparently the display
system could display up to eight rows of alphanumeric information.
The other microcoded engine, which was essentially a small general-purpose
CPU, performed the math operations and handled the programmability of
the machine. Both read-write (for general storage) and read-only (for
microcode) memory was based on magnetic core technology. A clever technique
of using additional wires strung through the cores allowed the core memory
system to act both as read-write and read-only memory depending on the
wires used to address it.
The LOGICON Computer had two modes of programming; one which was basic
learn-mode programming, where the calculator would remember sequences of
keypresses, with keyboard-based instructions for conditional testing
and branching, allowing moderately complex programs to be developed. It
is not known how many program steps the system could store, though
apparently rather complex programs could be stored in the machine's
memory, indicating that the learn-mode program storage capability
was fairly substantial. The learned keypresses could be then "ran" as a
program, with programmed stops to allow user input of variable data.
The other programming mode was more like conventional computer programming,
where the calculator would be programmed at the CPU's "machine code"
level, allowing for much more sophisticated programming capabilities.
The machine code instructions were eight bits in length, with Binary-Coded
Decimal (BCD) and pure binary addition and subtraction, BCD and binary
right and left-shift, conditional test and branch, and input/output
instructions. Data stored in core memory could be addressed directly or
indirectly, with various modifiers to allow easy manipulation of strings
of binary-coded digits used for the calculators math operations.
Development of the calculator began sometime in early 1963, with the goal
to develop a simple-to-use computing device that engineers could use to
perform their complex calculation tasks without having to use expensive
mainframe computing resources. Development took about two years,
with the first prototype becoming operational in early to mid-1965.
The first machine was thoroughly checked out and deemed ready for
general use, just in time for the company to move its office from
Redondo Beach, CA, to San Pedro, CA, which occurred in the summer of 1965.
Once the move was completed, the calculator was set up in a common room
that contained about a dozen rented electromechanical calculators made by
Friden and Marchant that engineers could use for their computational needs.
Once engineers got used to the LOGICON Computer, use of the electromechanical
calculators dropped off drastically, and not long thereafter the rental
agreements were terminated and the Friden and Marchant machines were
returned. At least one more LOGICON Computer was built because the
existing machine was in great demand, and also because there was a desire
to build a more refined "product-ready" machine for potential sale.
It is believed that up to four more LOGICON Conputers may have been built,
however, it is only positively known that two machines were built.
The LOGICON Computer was never offered for sale as a product. However,
the second machine built (included in the total count of two to six that
were built altogether) was built as it would be if the machine were to be
a commercial product, at a cost of somewhere around $24,000, with the
intention to use the machine as a demonstrator to show to established
calculator companies wishing to license the design for their own use.
Part of this effort involved generation of and application for a US patent
on the design. The patent was applied for in August of 1966, and
US Patent Number
3,487,369 was granted on December 30, 1969.
The plan was that a licensee would pay a flat fee for the license,
as well as a royalty
for each machine sold. The license would allow the licensee to
manufacture, sell, and support their branded version of the
LOGICON Compter to the open market. It appears that Monroe Calculating
Machine Co. specifically, as well as a few other calculating machine
companies were shown the machine. Sadly, insufficient interest was
generated, and after a time, it was decided to abandon the licensing
effort, likely sometime in mid to late 1966.
It was also at this time
that Logicon management decided that there was no merit in pursuing
the calculator further as such a venture was outside the company's
core business, and the project was ended. The existing calculators
continued to be used internally for engineering calculations, likely more
advanced calculators were available commercially that provided more
advanced functionality for a very reasonable price.
It is not known what happened to the machines after they were
no longer used.
If Logicon had gone ahead with making the LOGICON Computer
a commercial product back in the mid-1960's, it would have certainly been
the most powerful programmable desktop electronic calculator on the market
at the time, easily outshining the four existing programmable calculators,
which were the
Monroe's EPIC 2000,
Wyle Laboratories' WS-01/WS-02,
Wang Laboratories' LOCI-2
programmable calculators. It likely would have held that title
until the introduction of the HP 9100 in 1968.