Factual information about CPU computer architecture and processing

CPU

The Central Processing Unit of a computer: Facts about CPUs

While the human head is estimated to weigh approximately seven pounds, the 'brain' of a modern computer is far tinier. CPU is the acronym for the Central Processing Unit of a computer. It is responsible for the executive functions of the computer. It interprets and then issues the "commands from the computer's hardware and software" (Fischer 2013). The CPU "has a program counter that points to the next instruction to be executed. It goes through a cycle where it retrieves, from memory, the instructions in the program counter. It then retrieves the required data from memory, performs the calculation indicated by the instruction and stores the result. The program counter is incremented to point to the next instruction and the cycle starts all over" (Davis 2005). Because it is responsible for all of the computer's instructions and calculations it is called a 'processing' unit and the fact that the CPU is located in the middle of most computers to keep its cables short is why it is 'central' (Davis 2005).

A modern CPU is usually very small. (Fischer 2013). However, during the 1970s, this was not the case: computers were large, refrigerator-size units, due to the size of the complex machinery needed to govern their actions. "The CPU was a big pile of equipment. The thought that the CPU could be reduced to a chip of silicon the size of your fingernail was the stuff of science fiction" (Davis 2005). All of this changed with the revolutionary invention of the Intel Corporation in 1971. The first small CPU was designed for a business calculator that could be held in the palm of the user's hand. "The original 4004 microprocessor chip handled data in four bit chunks. Four bits gives you sixteen possible numbers, enough to handle standard decimal arithmetic for a calculator" (Davis 2005). The original four 'bit' microprocessor was eventually scaled up to 8. "In 1979, Intel delivered the 8088 and IBM engineers used it for the first PC. The combination of the new 16 bit microprocessor and the name IBM shifted the personal computer from a techie toy in the garage to a mainstream business tool" (Davis 2005). The MOTOROLA 6800 - Microprocessor of 1979 was used by Apple for the Macintosh computer (Computer hardware, n.d., Computer Hope Newsletter).

Today's CPUs are tiny, but powerful: "modern processors contain millions of transistors which are etched onto a tiny square silicon called a die, which is about the width of a standard thumb" (Computer hardware, n.d., Computer Hope Newsletter). Until recently, most CPUs were Intel processors. "Today the market is being shared by other companies such as the popular AMD processor manufactured by the AMD company" (Computer hardware, n.d., Computer Hope Newsletter). A contemporary CPU has "many short, rounded, metallic connectors on its underside….The CPU attaches directly to a CPU 'socket' (or sometimes a 'slot') on the motherboard. The CPU is inserted into the socket pin-side-down and a small lever helps to secure the processor" (Fischer 2013). CPUs generate a great deal of heat, and a heat sink and a fan are necessary to prevent the system from overheating. The positioning can be seen in the following diagram for a standard Intel CPU: