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The Z22 was the seventh computer model Konrad Zuse developed (the first six being the Z1, Z2, Z3, Z4, Z5 and Z11, respectively). One of the early commercial computers, the Z22's design was finished about 1955. The major version jump from Z11 to Z22 was due to the use of vacuum tubes, as opposed to the electromechanical systems used in earlier models. The first machines built were shipped to Berlin and Aachen.
By the end of 1958 the ZMMD-group had built a working ALGOL 58 compiler for the Z22 computer. ZMMD was an abbreviation for Zürich (where Rutishauser worked), München (workplace of Bauer and Samelson), Mainz (location of the Z22 computer), Darmstadt (workplace of Bottenbruch).
In 1961, the Z22 was followed by a logically very similar transistorized version, the Z23.
In the 1970s, clones of the Z22 using TTL were built by the company Thiemicke Computer.
The typical setup of a Z22 was:
- 14 words of 38-bit RAM implemented as core memory
- 8192 word (38 KiB) magnetic drum storage
- punched card memory as bulk memory (input/output)
- 380V 16A three phase power supply
- 600 tubes working as flip-flops
- electrical cooling unit, needing a water tap connection (water cooling, so to say)
The Z22 operated at 3kHz operating frequency, which was synchronous with the speed of the drum storage. The input of data was possible via punch-card reader and by directly programming drum storage or core memory using pushbuttons. The Z22 also had glow-lamps which showed the memory state and machine state as output.
The Z22 was designed to be easier to program than previous first generation computers. It was programmed in machine code with 38-bit instruction words, consisting of five fields:
- the first 2 bits must always be 10
- the next 5 bits contain a condition symbol
- the next 13 bits contain an operation symbol
- the next 5 bits contain a core memory address
- the next 13 bits contain a drum memory address
There also was an assembly-like programming language called "Freiburger Code". It was designed to make programming programs for solving mathematical problems easier than writing machine code, and reportedly did so.