All processors use Is and Os, where each 1 or 0 is a bit. Eight bits grouped together are known as byte. The letter A looks like 01000001 to the processor. Each character on a keyboard appears as one byte to the processor. The number of bits processed at one time is the processor's word size. Each word contains eight bytes. The word size of early Intel processor, like 8086, was 2 byes or 16 bits. Today's processors have word sizes of 32 bits. Future processors will have word size of 64-bits and even higher.

The Is and Os must travel from one place to another inside the processor as well as outside to other electronic chips. To move Is and Os around, electric lines called a bus are used. The electronic lines inside the processor are known as internal data bus. In earlier Intel processors like 8086, the internal data bus is comprises of 16 separate lines with each carrying Is and Os. The word size and number of lines for the internal data bus are equal. For example, Intel's 8086 processor had a 16-bit word size and 16 lines carried 16 bits on the internal data bus. In today's processors, several groups of 32 internal data bus lines operate concurrently.

For the processor to communicate with the other devices, the Is and Os travel on the external data bus. The external data bus connects the processor to expansion slots, keyboard, mouse, floppy drive, hard drive and other devices. The external data bus is also known as the external data path. One can see external data lines by looking between the expansion slots on rhe motherboard. Some solder lines between the expansion slots are used to send data out along the external data bus to the expansion slot. The Intel's 8086 had an 8-bit external data bus. Today's processors have 64-bit external data paths.

There are many types of processnrs that are found in the different computer types - we will concentrate on the Intel family of processors. CPU components include the following:

• Arithmetic Logic Unit (ALU): carries out arithmetic and logic operations
• Control Unit (CU): coordinates and controls all system operations
• Registers: special-purpose temporary storage locations where contents can be accessed and altered much faster than locations in main storage
• Program Counter: holds the address in memory of the next instruction to be executed.