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The Life and Work of Konrad Zuse (by Horst Zuse) |
| Part 7 (continued): The Zuse KG |
| The Z5 Computer In 1950, the Leitz Company in Wetzlar ordered a big relay computer, the Z5. Fig.74 and Fig.75 show the Z5 and the employees of the Zuse KG in 1952, who built the Z5. Like the Z4, the Z5, which was sold for 300,000 DM, was also a great success for the Zuse KG. |
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| Fig.74 (Left). The Z5 was an extended version of the Z4 and was delivered to the Leitz Company in 1952. The machine had about 3,000 standard relays and more than 30 stepwise relays. Fig.75 (Right). The Zuse KG built the Z5 from 1950-1952 with about 30 employees. | |
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For the Z5, Konrad Zuse used 2,800 uniform modern telephone relays in order to overcome the bad reliability of vacuum tubes. The machine itself occupied an area of 10 meters by 4.5 meters, while the input and output devices required 2.5 meters by 4.5 meters. The Z5 was the first commercial computer ever built in Germany (probably in Europe) and delivered to a company in Germany. Also, the Z5 was the greatest relay computer ever constructed and delivered in West-Germany (in 1955 the OPREMA, which used 17,000 relays, was constructed in East-Germany).
The Z5 was six times faster than the Z4, had a twelve word memory (each containing 35 bits, so floating point numbers were represented using 1 bit for the sign, 7 bits for the exponent, and 27 bits for the mantissa), and a special memory to store eight constants (such as: +0, +1, +10, +Pi, +1/3, + 1/5, +1/7, +220). The Z5 was a three address machine and had a clock frequency of about 40 Hertz. It is important to note that the Z5 was not a stored program machine, because the program was not stored in the memory along with the data. Instead, the Z5 employed a sub-program technique realized using three punch tape readers (based on 35 mm standard movie film), which were activated by each other. The punch tape readers read twelve 20-bit combinations per second (instructions and/or floating point numbers). Although the memory was very small, it was possible to perform the complicated calculations of the numerical methods required for optical lens systems. The execution times were 0.1 seconds for an addition, 0.4 seconds for a multiplication, 0.75 seconds to perform a division or a square square root, 0.05 seconds to multiply a floating point number with a constant, and 0.4 to 1.4 seconds to convert a floating point number into its decimal equivalent, or vice versa. The calculation of the root of an algebraic equation of the 8th degree took around 38 seconds, and the calculation of a determinate of the 4th degree took around 15 seconds. However, the Z5 was the only big mandate that the Zuse KG got between 1949 and 1955. At this time, 300,000 DM was a large amount of money. The monthly income of a typical family was less than 200 DM. After the Second World War, the situation in Germany and Europe was very difficult. Up to 60% of Germany was destroyed and the capacity of the German economy was less than 20-30% compared to 1939. Thus, companies simply didnt have enough money to buy computers. For this reason, Konrad Zuse tried to make some business with US companies. He successfully concluded a contract with the Remington Rand Corporation, which meant he could sell about 50 small relay machines (Z7-Z9). With the exception of the G1 research computer in Göttingen by the team of Billing, and the institutes in Darmstadt and München, the German government did not support institutions for buying computers until around 1955. The Z11 Computer |
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| Although the situation in Germany was very difficult, in 1954 the Zuse KG constructed the Z11 as a successor of the machine SM1 (1952-1954), which was developed by Seifers in München for consolidation of farming purposes. The Z11, which had a clock frequency of 40 Hertz, was very popular because of the easy handling by the hardware wired(9) programs. These programs solved calculations in the area of consolidation of farming by pressing simple buttons. | (9)Hardware wired programs are implemented using relays and stepwise relays. The stepwise relays select micro-sequences of algorithms implemented with relays. Freely programmable machines whose programs are stored on a punch tape or a punch card are much more powerful than hardware wired programmed machines. | |
| From 1955, the Z11 was ordered by surveyors offices for the consolidation of farming. In 1956, it was extended with punch tape readers and was made freely programmable by a punch tape. The Z11s word length of 38 bits (high accuracy) and its floating point arithmetic made this machine very popular in the optical industry and in universities. In 1956 the Zuse KG only sold five Z11 computers, but by 1959 the situation had changed and the Zuse KG could sell 35 Z11s (the price of the Z11 was 100,000 DM in 1959). At this time the German optical industry was the leader in the world, and almost every company producing optical equipment in Germany had ordered a Z11. From 1955, the DFG (Deutsche Forschungsgemeinschaft) gave money to install computers in universities. | |
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| Fig.76 (Left). The Z11 computer was initially used for the consolidation of farming. Later it was extended to a freely programmable machine and was used by the optical industry. Fig.77 (Right). The Z11's memory with about 20 words of 38 bits and the wiring pattern. | |
| The Graphomat Z64 In 1955, Konrad Zuse began development on the Graphomat Z64, which was a drawing machine with an accuracy of 1/20 mm. |
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| Fig.78 (Left). The Zuse Graphomat Z64 was used for accurate drawings in science and commercial applications (1964). Fig.79 (Right). The two gearboxes, which could transform digital impulses into 15 different speeds for drawing lines and curves (these gearboxes were later replaced by stepper motors). | |
| With the Z64, Konrad Zuse tried to realize another vision. He wanted to build drawing machines in order to make the results of complex calculations more understandable and more visible. The Z64 was controlled by a punch tape, which was created by the computers Z22, Z23, Z25, or Z31 (these machines are introduced below). The movement of the drawing pencils was controlled by two gearboxes, which could transform digital impulses into analog drawings. The gearboxes were invented and constructed by Konrad Zuse in 1955-1957. The Graphomat Z64 was a very reliable and well-accepted machine in industry and research institutes. The high accuracy of drawings, the reliability, the low maintenance costs, and the enormous variety of applications were highly appreciated. | |
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