How Computers Work

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This ebook, by Roger Young, explains computers as electrical circuits consisting of switches and relays (subsequently equated to transistors). It begins with simple circuits showing how, from first principles, switches and relays work. These are then combined in increasingly complex arrangements to simulate logic gates and memory.

The execution of code in the processor is discussed, with a detailed description of binary operations. A complex circuit model of addressable memory is provided with associated truth tables. Bit operations are explained, again through a series of circuit diagrams, leading to the creation of a Logic Unit for a simple processor. The operation of a clock is also explained and used within the processor circuit. Bitwise programming of 4 bit, and then 16 bit, computers is explained and programs are created for addition, multiplication and branching.

The resource is suitable for older students studying electronics and / or computer science, and provides a very different way of thinking about computer hardware.

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