Computers: The Past, Present, and Future -- Present

Computers: Present: Tutorial

CPU Revisited

So you’re saying, "that’s great and all, but what is the processor"? Well, there is more to a processor than you would think. The processor is composed of the following components: math coprocessor, clock speed, internal cache memory, and the bus (external or system, data, and address).

Math Coprocessor

The math coprocessor is simply a nice addition to the CPU, but not a requirement to function. Originally, the math coprocessor was an addon to the CPU that you would buy separately, but since the development of the 486 processor, the math coprocessor has been built in. The math coprocessor speeds up the computer's "number crunching" ability for floating point and/or decimal operations.

Clock Speed
Clock Speed is the main concern of every computer enthusiast. The clock speed is comparable to the speed you travel in a car. In computer terms, this the frequency that a processor executes instructions. Clock speed is measured in millions of cycles per second (MHz). There is a natural clock of sorts within the CPU. Basically, the clock is composed of a quartz crystal, which vibrates as electricity is sent through it. This vibration is sent as an electric pulse to other electronic devices synchronized with the clock. Every "clock tick" or pulse sent by the clock signals the processor to compute the next instruction.
Internal Cache
The internal cache is RAM designed primarily for the CPU. It stores the data and instructions used by the CPU. In most modern PC's, the CPU comes standard with 512KB of cache. A general trend is observed that the larger the cache the faster the CPU runs. The Bus
The Bus is the underlying circuitry of the computer. The bus allows devices to be connected on the motherboard to communicate. It is composed of the external, data, and address bus.
External Bus
The external bus is also called the system bus or expansion bus. The external bus allows the CPU to communicate with other devices. It is called the external bus because of its location outside of the processor. The expansion bus is located directly on the motherboard.

Data Bus

The data bus is the "highway" of the computer. It is used to send and transmit data. The larger the bus width, the more data that can be transmitted. In a data bus, the amount of data that can be transmitted at one time is the bus width. For example, a 32-bit bus has 32 wires that can transmit a signal at any given time. Therefore, the more bits per chip signifies a greater amount of information that can be transferred at one time.

Address Bus

The address bus is a system of wires used to transfer information in and out of the processor about memory address locations. The address bus is imperative to other parts of the CPU because without it the CPU would not know what section of the RAM to access for information. Similar to other devices, the address bus follows the trend: "The larger the better". A larger address bus allows the CPU to access a greater amount of memory. For example, in the Intel 286 the address bus was 24-bits, which allowed it to access 16MB of memory. Whereas, in the Intel 386, the address bus was 32-bits, which allowed it to access up to 4GB of memory.
Wow, you have now made it through a lot of steps in the tutorial. If you would like to continue your journey today, please do with Expansion Bus.

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