A computer that refuses to die
A photo – Daderot – PD / In the photo: FACOM 128B follower – FACOM 201A
How FACOM appeared
In the early 1950s, computers were built on electronic tubes – they were used in the first commercial computer Ibm model 701. These items were difficult to maintain and often failed. Therefore, some companies chose a different path and began to develop electromechanical computers based on relays and switches. Among them was the Japanese Fujitsu Corporation. She planned to compete with the American “blue giant“.
In 1954, Toshio Ikeda, head of computer technology at Fujitsu, initiated the development of a new computing system. In it the role of logical elements were playing switching relays used in telephone exchanges. The company’s engineers used 4,500 of these relays and assembled a computer from them. FACOM 100. Two years later, an improved version of the system saw the light – FACOM 128A, and in 1959 – FACOM 128B.
Computer features
Fujitsu’s performance was significantly lower than that of electronic lamp machines. For example, IBM 701 was spending the addition operation is about 60 milliseconds. FACOM 128B similar task performed in 100-200 milliseconds. It took up to 350 milliseconds to multiply two numbers, and much more for complex logarithmic operations.
The lack of performance FACOM 128B made up for reliability and ease of maintenance. All arithmetic operations were performed in the decimal system, and the numbers were encoded with a binary-five-digit code (bi-quinary) To indicate the number in memory, seven bits were allocated – 0 5 and 0 1 2 3 4, which allowed you to encode any digit from zero to nine, “lighting” two bits in the sequence.
Such an approach greatly simplified search for stuck relays. If the number of active bits is not equal to two, then it became obvious that a failure occurred. Finding a faulty component after that was also easy.
The FACOM 128B computer was used until the 1970s. With its help, they designed special lenses for cameras and NAMC YS-11 – The first passenger airliner built by the Japanese after the end of World War II.
How’s FACOM doing today?
FACOM 128B is no longer used for any serious calculations and calculations. The car turned into a full-featured museum exhibit installed in the “hall of fame” of the Fujitsu Numazu Plant in Numazu.
The computer’s performance is monitored by a single engineer, Tadao Hamada. By his according to, he will “remain on the post” for the rest of his life, as he wants to preserve Japan’s technological heritage for posterity. He notes that repairing the system does not require significant effort. The FACOM 128B is so reliable that it only needs to be replaced with one relay per year, despite daily demo runs.