CPU-Central Processing Unit. The processor is the main thinking part of the computer. It receives all the instructions and processes them. Their are many kinds of processors, right now the most used processor is the Pentium processor by Intel. There are two kinds of processors CISC and RISC, RISC is better but because software has to be made specifically for it and the market is not that large currently most software is made for CISC chips. Also because of this processors that have a RISC chip also have a CISC chip. When you buy a computer whether you know why or not, you are concerned with the amount of Mhz the machine has, the higher the better (of course only within a type of chip, a 486 with 100Mhz is not faster than a Pentium with 90Mhz), the Mhz are related to clock speed of the processor. First I will explain how the information is input into the processor and output and then explain the chips within that process the data, CISC and RISC.

First the very simple version:

1. Information is received from RAM and is sent to caches.

2. Information is decoded and processed.

3. Lastly it is output back into the system.

CISC part:

1. Information is analyzed for how much memory will be needed and sets aside the right amount.

2. Microprocessor finds how to store and load the command, which then sends the command to be decoded.

3. Command is broken down and processes information one step at a time.

RISC part:

1. Finds what inputted commands will not affect other commands and then processes up ten commands at the same time.

Detailed part:

How the microprocessor of a Pentium processes information:

1. The bus interface unit (BIU) receives data from the RAM through the bus at 64 bits at a time.

2. BIU sends data along two 64 bit paths one to the code cache (used for code only to tell the processor what to do with the data) and the other path is to the data cache (which is used to only store the data).

3. The code cache sends information to the branch predicator unit which tells which arithmetic logic unit (ALU) is more appropriate for the task at hand, which would include making sure ALUs are being used.

4. After determining which ALU should be used from the branch predicator unit it is sent to the instruction prefetch buffer. Which decode the data for the ALUs to understand.

5. Each ALU takes the information and writes on the register which is like a white board where notes are taken and erased. Also some of the information from the instruction prefetch buffer is sent to the floating point unit which deals with any numbers with decimals.

6. The information from the register and floating point unit are sent to the data cache and is then sent back out to the bus interface unit and back to the bus.

How a CISC processor works:

1. In a CISC's microprocessor is some read-only memory that contains many commands which also have sub-commands which are used to complete an operation.

2. The microprocessor sees how many bytes of room the command needs and sets aside enough memory.

3. The microprocessor must determine how to load and store a command.

4. The command is sent to a decode unit which breaks the code into microcode which is sent to the nanoprocessor.

5. The nanoprocessor take one instruction at a time and some instructions may need to go through several steps.

How a RISC processor handles information:

1. The commands have small instructions for one job and applications tell the processor what combination of smaller commands should be used for a large operation.

2. RISC commands are all the same size and can only be stored and loaded one and do not need to be decoded into microcode. The RISC chip figures which commands are not affected by others and process them first and can execute ten at the same time. RISC chips use less transistors and have shorter circuits so they process information faster.