The Z22 computer

Z22 history

After the Z1, Z2, Z3, Z4, Z5 and Z11 the Z22 was the seventh computer model Konrad_Zuse developed. It was one of the first commercial computers; probably a Z4 was the very first computer sold commercially. The design of the Z22 was finished about 1955, the first computers built were shipped to Berlin and Aachen. It's said that the Z22 was the first computer with magnetic storage. As core memory and drum memory were invented earlier and were - by hearsay - used in military computer prototypes before, this isn't assured knowledge, though.

Z22 technical data

The typical setup of a Z22 was:

• 14 words of 38-bit RAM implemented as core memory
• 38kByte magnetic drum storage
• punch-card memory as bulk memory (input/output)
• 380V 16A three phase power supply
• 600 tubes working as flip-flops
• electrical cooling unit, needing an own 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 not only possible via punch-card reader, but also by directly programming drum storage or core memory using pushbuttons. The Z22 also had glow-lamps which showed the memory- and machine state as output.

Z22 programming

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 5 fields:

• the first 2 bits must always be 10
• the next 5 bits contain a condition symbol
• the next 13 bits contain a 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.

Z22 today

There are probably some Z22 rotting away somewhere in europe; anyway, the Fachhochschule Karlsruhe still has an operational one.

Z22 external links

Z22 computer emulator

Homepage of the Z22/13 of the university of Karlsruhe (German!)