APEXC

The APEC, or All Purpose Electronic Computer series was designed by Andrew Donald Booth and built by Kathleen Booth at Birkbeck College, London in the early 1950s. Their work on the APEC series was sponsored by the British Rayon Research Association. Although the naming conventions are slightly unclear, it seems the first model belonged to the BRRA. According to Booth, the X stood for X-company.
One of the series was also known as the APEC or All Purpose Electronic X-Ray Computer and was sited at Birkbeck.

Background

From 1943 on, the Booths started working on the determination of crystal structures using X-ray diffraction data. The computations involved were extremely tedious and there was ample incentive for automating the process. Andrew Booth developed an analogue computer to compute the reciprocal spacings of the diffraction pattern.

ARC and SEC

The Booths designed an electromechanical computer, the ARC, in the late 1940s under the sponsorship of the British Rayon Research Association.

Later on, they built an experimental electronic computer named SEC.
Booth designs the All-Purpose Electronic Computer in 1950.
Booth builds the first full-scale prototype in his father's barn 1950–1951.
Early 1951, BRRA commissions Booth for a version of the APEC, named APEC.
British [Tabulating Machine Company|BTM] sends engineers to visit the barn where the APEC is being assembled, to copy the circuitry of the computer—which they then use to build the HEC 1.
and finally, the Booth team markets the APEC series.

The computers were programmed by Kathleen Booth.

Year	Activity	Machine
1947–1948	Sponsored design research and travel to the US.	ARC
1948–1950	Sponsored design research and travel to the US.	SEC
1951	Commissioned a dedicated electronic version.	APEC
1952	Delivery and first successful operation of the machine.	APEC

The APE(X) C series

The APEC series included the following machines:APEC: Birkbeck College, London, first time operated in May 1952, ready for use at the end of 1953APEC: Board of Mathematical Machines, Oslo, also known as NUSSEAPEC: British Tabulating Machine Company C: British Rayon Research Association, ready for use in June 1952UCC: University College, London MAC or MAGIC : "built by Wharf Engineering Laboratories"

The HEC, built by the British Tabulating Machine Company, then International Computers Limited ), a commercial machine sold in several models and later known as the ICT200 series. There were likely the derivatives HEC 1, HEC 2, HEC 2M - M for 'marketable' denoting the machine's orientation toward commercial rather than scientific customers, and HEC 4'''

Only one of each of these machines was built, with the exception of HEC which were commercial machines produced in quite large numbers for the time, around 150. They were similar in design, with various small differences, mostly in I/O equipment. The APEHC was a punched card machine while the APEXC, APERC and APENC were teletypers. Also, the UCC had 8k words of storage, instead of 1k word for other machines, and the MAC used germanium diodes in replacement of many valves.

British Tabulating Machine Company machines

In March 1951, the British Tabulating Machine Company sent a team to Andrew Booth's workshop. They then used his design to create the Hollerith Electronic Computer 1 before the end of 1951. The computer was a direct copy of Andrew Booth's circuits with extra Input/output interfaces. The HEC 2 was the HEC 1 with smarter metal casings and was built for the Business Efficiency Exhibition in 1953. A slightly modified version of the HEC 2 was then marketed as HEC2M and 8 were sold. The HEC2M was succeeded by the HEC4. Around 100 HEC4s were sold in the late 1950s.