Ferranti Mark 1 | 1951

 

The Ferranti Mark 1, also known as the Manchester Electronic Computer in sales documents, and sometimes referred to as the Manchester Ferranti, was the world's first commercially available electronic general-purpose stored-program digital computer, produced by the British electrical engineering company Ferranti Ltd.

While commercial digital computers had been developed before with BINAC and Z4, the Z4 was electromechanical and lacked software programmability, and BINAC did not operate successfully after its installation in India.

The Ferranti Mark 1 was a refined and commercialized version of the Manchester Mark I, designed by Freddie Williams and Tom Kilburn at the University of Manchester. The first machine was delivered in February 1951, with a public demonstration taking place in July of that year, prior to the UNIVAC I being sold on March 31, 1951, and delivered to the U.S. Census Bureau in December 1952.

The Ferranti Mark 1, based on the Manchester Mark I, incorporated several enhancements, including increased sizes for primary and secondary storage, a faster multiplier, and additional instructions. It stored 20-bit words in a single line of a Williams tube display, which was composed of charged spots. Each tube could store 64 lines of 64 spots. Instructions were stored as single words, while numbers were stored as pairs of words. The primary memory consisted of eight tubes, each capable of storing 64 words. Other tubes held an 80-bit accumulator (A), a 40-bit "multiplicand/quotient register" (MQ), and eight "B-lines" (index registers), which were distinctive features of the Mark 1 design. The accumulator could also address two 40-bit words. Each tube contained an additional 20-bit word for offset values to the secondary storage. The secondary storage was provided in the form of a magnetic drum with a capacity of 512 pages, storing two pages per track with an approximate rotation time of 30 milliseconds, offering eight times the storage capacity of the original Manchester machine.

Like the Manchester machine, instructions used a single address format, with operands modified to remain in the accumulator. There were approximately 50 instructions in total, and the basic cycle time was 1.2 milliseconds. Multiplication in the new parallel unit was completed in about 2.16 milliseconds, making it roughly five times faster than the original. The multiplier utilized nearly a quarter of the machine's 4,050 vacuum tubes. Several instructions allowed for copying or reading back words from memory to a paper tape machine using one of the Williams tubes. Some new instructions were added to the original Manchester design, including a random number instruction and several commands utilizing the B-lines.

The original Mark 1 required programming by inputting five-bit representations of alphanumeric characters, leading engineers to use the simplest mapping between punched holes and binary numbers. However, the mapping between holes and physical keyboards was not intended as binary, resulting in characters representing numbers from 0 to 31 (five-bit numbers) appearing completely arbitrary.

The first machine was delivered to the University of Manchester, and Ferranti had high hopes for additional sales, particularly buoyed by an order from an atomic research laboratory in the autumn of 1952. However, during the production of the second machine, a change in government led to the cancellation of all government contracts worth over £100,000, leaving Ferranti with a partially completed Mark 1. Eventually, this machine was sold to the University of Toronto, which saw an opportunity to acquire a complete Mark 1 at a low price, purchasing it for approximately $30,000. Beatrice Worsley, a prominent figure there, affectionately named it FERUT. FERUT was widely used for various purposes in business, engineering, and academia, including calculations for the construction of the St. Lawrence Seaway.

Alan Turing wrote the programming manual for the machine.

Following the first two machines, a modified version known as the Ferranti Mark 1 Star (or simply Ferranti Mark 1) was introduced. This modification primarily focused on streamlining the instruction set for improved usability. Instead of the original mapping of holes to binary numbers, the new machine created a much simpler mapping (ø£½0@:$ABCDEFGHIJKLMNPQRSTUVWXYZ) by mapping numbers to holes. Additionally, several instructions that utilized the index registers had side effects that complicated programming, which were corrected in the new design. The original JUMP instruction was placed "one before" the address, theoretically useful but practically inconvenient, so it was revised. The input/output method was also changed so that the least significant bit of the five-bit numbers was output on the right, which is standard in most numerical notation. These changes greatly enhanced the programming ease of the new machine.

The Mark 1/1 weighed 10,000 pounds (5.0 short tons; 4.5 tons).

Between 1953 and 1957, at least seven Mark 1 machines were delivered, one of which was installed at the Shell Research Laboratory in Amsterdam. Another machine was located at the Avro aircraft manufacturing plant in Chadderton, Manchester, and was used for various projects, including the Vulcan project.

Tim Berners-Lee, the inventor of the World Wide Web, had parents, Conway Berners-Lee and Mary Lee Woods, who worked on the Ferranti Mark 1 and Mark 1.

The Ferranti Mark 1's instruction set included a 'hoot' command that allowed the machine to provide auditory feedback to the operator. The generated sound could be tuned, which contributed to the Mark 1's early experiments in computer-generated music. It performed pieces such as "God Save the King," "Baa Baa Black Sheep," and "In the Mood." This recording was made by the BBC in late 1951, with programming managed by Christopher Strachey, a friend of Alan Turing and a mathematics teacher at Harrow. However, it was not the first computer to play music, as Australia's first digital computer, CSIRAC, had played "Colonel Bogey" earlier.

In November 1951, Dr. Dietrich Prinz wrote a chess program for the Manchester Ferranti Mark 1 computer, making it one of the earliest known computer games. Due to the limitations of the Mark 1, he could only program a checkmate problem with just two moves, analyzing all possible moves for both white and black (thousands of possibilities) to find a solution, which typically took 15 to 20 minutes. The program's limitations included restrictions on castling, double pawn moves, en passant captures, and pawn promotion, with no distinction between checkmate and stalemate.