The Z3 - 1941 built by Konrad Zuse - was the first freely programmable calculating machine of the world which is based on the binary number system. It is often called therefore today, particularly in the German-speaking countries, first functional programmable computer. 1944 were destroyed the Z3 by a bomb attack.

History

First the development of the full-mechanical Z1 and the transition model Z2 preceded the development of the Z3. 1941 were finally introduced the Z3 to a group by scientists. While the original in the war was destroyed with a bomb attack, a functional reproduction is in the German museum in Munich, which was made 1962 from the Zuse kg to exhibition purposes. The Z3 is called computer in general and not as computer, since this term developed only later, and are not there the programs put down in main storage.

Meaning

• First fully functional programmable computer
• For the first time use of the binary system
• Mostly non-mechanically
• Contains a great many characteristics of modern computers:
  • Floating-point number computation
  • In and output devices
  • Possibility of the user interaction during the computing method
  • Microprograms
  • Pipelining of instruction sequences
  • Numeric special values
  • Parallel execution of operations as far as possible

Also the Z1 had nearly all of the characteristics stated above, did not attain however not so much attention, since their arithmetic unit did not work very reliably due to the mechanical structure. The structure of Z1 and Z3 resemble general each other much, which applies in particular to the arithmetic unit.

Structure

The Z3 consists of

• a relay floating-point arithmetic unit for addition, subtraction, multiplication, division, square root, decimal dual and binary-to-decimal conversion. The arithmetic unit has two registers g 1 and R2.
• a relay storage from 64 words, ever 22 bits (1 bit sign, 7 bits exponent, 14 bits mantissa)
• a punched-tape reader for film strips, in order to read programs in (no data!)
• a keyboard with lamp panel for input and output of numbers and the manual control of computations

Enterprise

The Z3 is a clocked machine. Clocking is taken over by an electric motor, which propels a clock roller in such a way specified. This is a drum, which turns approx. 5,3 times per second, and during a turn the controlling of the individual relay groups takes over. The Z3 has the following machine instructions:

• Pr z - Memory cell z into register R1/R2 load - 1 cycle
• HP z - Write g 1 in memory cell z - 0 1 cycle
• Ls1 - Addition g 1: = g 1 + R2 - 3 cycles
• Ls2 - Subtraction g 1: = g 1 - R2 - 4 - 5 cycles
• Lm - multiplication g 1: = g 1 * R2 - 16 cycles
• Left - Division g 1: = g 1/R2 - 18 cycles
• Lw - square root g 1: = SQRT (g 1) - 20 cycles
• Lu - read decimal number in in g 1/R2 - 9 - 41 cycles
• Ld - spend g 1 as binary number - 9 - 41 cycles

The input of numeric data must be made by the keyboard, i.e. numbers cannot be coded on the paper tape. Over the keyboard all operations can be implemented except the memory accesses (Pr and HP) directly. The paper tape can contain only instructions. Each instruction on the paper tape is coded with 8-bits. The Z3 knows no branch instructions, is however (with the help of skillful utilization of the finite computational accuracy) as Rojas showed 1998.

Arithmetic unit

Each arithmetic operation of the Z3 is based on the addition of two natural numbers. This basis operation of the addition becomes by XOR (XOR (x, y), CARRY (x, y)) it computes, whereby CARRY (x, y) is the transfer function, e.g. CARRY (0011011,1010110) ==0111100.

• An addition of two floating-point numbers is realized by computation of the difference of the exponents, adapting of the mantissa of a number and finally addition of the mantissas corresponding afterwards.
• A subtraction corresponds to an addition, with that the complement of the second mantissa is used (complement = EMERGENCY (x) +1)
• A multiplication corresponds to an addition of the exponents and following multiplication of the mantissas. The multiplication of the mantissas is realized thereby by an iterative addition: 1011*0101 = 1011 + 10110*010 = 1011 + 101100*01 = 110111 + 1011000 * 0 = 110111
• A division corresponds to a multiplication, however the exponents are subtracted and an iterative subtraction for the division of the mantissas is used.
• The algorithm for pulling a root is realized by an iterative division (see patent specification).

Generally the arithmetic unit consists of two parts, a work for the calculation with exponents and a work for the calculation with mantissas. For instructions to head for with which iterative methods are used (Lm, left, Lw, Lu, Ld), a sequencer used, in order individual parts of the arithmetic unit. This corresponds to roughly modern microprograms.

Literature

• Rojas, Konrad Zuse's Legacy: The Architecture OF the Z1 and Z3, IEEE Annals OF the History OF Computing, 19:2, (1997), 5-16.

Related links

• Published Konrad Zuse Internet archives great source of information with nearly all of Zuse papers, patent specification, Java applet and photographies
• Zuse information page of refuge Zuse very good introductions and detailed discussions of the Z-series.
  • The computer Z3
• Count Multimedia show at the Urcomputer (Shockwave)

Articles in category "Zuse Z3"

We found here 3 articles.

Related Websites

We found here 6 related websites.

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