The Invention of the Relay Logic Computer
Although based on relays, the Z3 was very sophisticated for its time; for example, it utilized the binary number system and could perform floating-point arithmetic which could be used for complicated arithmetic calculations. Konrad Zuse (1910-1995) also developed the first real programming language, Plankalkül (“Plan Calculus”) in 1944–45. Zuse's language allowed for the creation of procedures (stored chunks of code that could be invoked repeatedly to perform routine and subroutine operations such as taking a square root, and structured data (such as a record in a database, with a mixture of alphabetic and numeric data representing, for instance, name, address, and birth date). In addition, it provided conditional statements that could modify program execution, as well as repeat, or loop, statements that would cause a marked block of statements or a subroutine to be repeated a specified number of times or for as long as some condition held. Zuse was an amazing man who was years ahead of his time. To fully appreciate his achievements, it is necessary to understand that his background was in construction and civil engineering - not electronics. More information about Konrad Zuse and his computers: Konrad Zuse and his computers Konrad Zuse Internet Archive The Life and Work of Konrad Zuse - Wikipedia Konrad Zuse (1910 - 1995) - Kerry Redshaw Konrad Zuse - about.com School Projects and Experiments With Relay LogicKonrad used relays to built logic gates - an arrangement of electronically-controlled switches used to calculate operations in Boolean algebra. Logic gates can also be constructed from diodes, fluidics, optical and mechanical elements. However, modern digital computers are built almost entirely from transistorized versions of these logic gates. Nikola Tesla filed the first patent for the AND logic gate in July 1900. Implementing Logic Gates With Relays
The general idea behind an AND gate is: If A AND B (both) take the logic value "1", then Q will be also "1", otherwise Q will take the logic value "0". This behavior is detailed in the truth table for the AND gate above. The same applies to the relay AND gate shown above: If we apply, both, A AND B points 6V, then Q will be 6V (otherwise Q will be 0V). This happens because when we apply 6V to both A and B, both relays R1 and R2 are activated and both contacts, which are connected in series, are closed and Q gets 6V. In other words, in a relay gate (or a transistorized one) the 1's and 0's are replaced by two different voltage values, in our case 6V and 0V (ground) respectively (other voltage values are also possible). In the same way we can also build an OR relay logic gate, but with one modification, instead of the two relay contacts being connected in series, like the case of the AND gate, the contacts will be connected in parallel. The same explanation applies to other logic gates (though different truth tables) - NOT, XOR, NOR, NAND which all of them could be build from relays. More about Logic Gates and Relays: Relays and Adder/Subtractors - Prof. William T. Verts Electromechanical Relays - Paul Smart Implementing Gates with Relays - howstuffworks Relay - Wikipedia Logic Gate - Wikipedia Science Fair Projects with Relay Logic Gates
Binary Adder - Wikipedia Simple Adders - howstuffworks Relays and Adder/Subtractors - Prof. William T. Verts Adding Binary Numbers - Ken Bigelow Half Adders, Full Adders, Ripple Carry Adders - Charles C. Lin Half and Full Adders - Doug Gingrich A Binary Adder - Donn Stewart Boolean Algebra Tutorials Boolean Algebra - Duncan Gillies Boolean Algebra - David Belton The Mathematics of Boolean Algebra - J. Donald Monk, Stanford Encyclopedia of Philosophy Boolean Algebra Tutorial - Basic Electronics Tutorials by Wayne Storr Universal Functions of Boolean Algebra - BBC Digital Logic - HyperPhysics Boolean Algebra and Logic Circuits - Deepak Kumar Tala Books
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