1. Hardware & Software
The CPU &
Memory

2. The Central Processing Unit
The central processing unit is the main chip in the computer.
CPU: Central Processing Unit
The CPU processes instructions, performs calculations and manages the flow of information through a computer system.
The CPU performs millions of calculations every second.
Currently, CPU speed is measured in MHz or GHz

3. The Central Processing Unit
Data is transported from RAM to the CPU for processing

4. The Central Processing Unit
The CPU has two main parts.
The control unit and the ALU
The ALU is the arithmetic/ logic unit.
It performs arithmetic operations such as addition
and logic comparisons such as 12 > 4
5. The results are transported back along the data bus to RAM
ALU
Control Unit
RAM
Register 1 2
Register 2 4 6
Accumulator
1. Data is transported along the data bus to the ALU registers
ADD
2. Instructions are transported to the control unit
3. The control unit indicates which operation should be carried out
4. The ALU carries out the operation and puts the results in the accumulator

5. Choosing a CPU Manufacturer:
Most popular CPUs for Personal Computers (PC) are made by Intel.
Other CPU manufacturer’s are AMD and Cyrix.
Generation:
·  Each generation of CPUs is more powerful than the last.
·   Newer CPUs can process more instructions at a time.
·  Generations include 286, 386, 486, Pentiums, Pentium MMX, Pentium II, Pentium III and currently Pentium IV.
Speed:
·   Each CPU generation is available in different speeds.
·  The CPU speed is a major factor in determining how fast a computer operates.
·  Generally, the faster the speed, the faster the computer operates.  The speed of a CPU is measured in megahertz (MHz or GHz).

6. Types of CPU Pentium: Pentium MMX: Pentium II & III: Celeron:
Intel’s Pentium Chip, ideal for computers using Windows 3.1 / 95 and 98.
Commons speeds: 75, 90,133, 166 and 200Mhz.
Compatible CPU chips include Cyrix 6x86 & GX as well as AMD-K5 chip
Pentium MMX:
Advancement of the Pentium chip to include Multimedia Extensions, referred to as MMX.
MMX improves multimedia tasks such as processing graphics, video & sound.
Pentium II & III:
Support MMX technology for improved multimedia performance.
Speeds from 233Mhz up to 600Mhz.
Compatible CPU chips include Cyrix 6x86MX & MII, as well as AMD-K6 chip.
Celeron:
Fast and inexpensive CPU chip, made by Intel.
Based on Pentium II chips, but with less built-in memory.
Meets the needs and budgets of most home computer users.
Current /Future:
The next generation of CPUs have bridged & exceeded the 1000Mhz or 1GHZ barrier. These include Intel P4 and AMD-Athlon, AMD-Duron and AMD XP

7. Computer Memory Two Types of Computer Memory Primary Storage (memory)
Below is a picture of 72 pin RAM. Used in PI and PII computers.
Today we currently use Dimms or DDR RAM
Two Types of Computer Memory
Primary Storage (memory)
RAM and ROM
Secondary Storage
hard drives, floppies, CD-ROMS magnetic tape, etc

8. Primary Memory - RAM
The pattern in the top row represents the letter A
RAM is short for Random Access Memory
Every RAM location -
has an address and holds one byte of data. Remember, a byte is made up of 8 capacitors that are called bits.
A charged capacitor would represent an ON bit or 1
An uncharged capacitor would represent an OFF bit or 0
RAM is used to hold data temporarily before and after it is processed
A different pattern might represent a different letter or even a number

9. Primary Memory - RAM What’s so important about RAM?
RAM holds application software instructions and data
What’s so important about RAM?
RAM holds data ready to be sent to the processor.
RAM also holds the instructions for how to process the data.
RAM also holds operating system instructions that control the basic functions of the computer. Every time you boot up a computer, these instructions are loaded from the hard disk into RAM ready for when the processor wants them. The instructions stay in RAM till you switch off the computer.
RAM also holds Operating System instructions

10. Primary Memory - RAM Ram Capacity:
A high specification computer may have large amounts of RAM.
Currently, it is quite possible to have up to 3 gigabytes of RAM.
This is the nearly
3000 megabytes of RAM
Ram Capacity:
The storage capacity of RAM is measured in megabytes. Typically a PC today would have about 512 Mb or RAM
The amount of RAM your computer needs depends on the operating system you are running and what application software you have.
Windows XP requires more RAM than say Windows 98
Modern motherboards will typically have three slots for RAM. Each slot may take up to 512 Mb or more of RAM depending on the motherboard.
Older motherboards cannot hold as much RAM

11. Primary & Secondary Storage
Differences
RAM is volatile.
Secondary storage is non-volatile
Volatile means that power is required to keep hold of the data
If the power is turned off the data is lost
Ram is volatile. This means it requires power to hold data. If the computer is turned off then all the data is lost.
A hard disk holds data even when the power to the computer is turned off

12. Primary & Secondary Storage
Differences
RAM: accessing data is faster
Secondary storage: accessing data is slower

13. Read Only Memory The computer BIOS is Read Only Memory (ROM)
ROM is READ ONLY MEMORY.
There is a ROM chip on the computer motherboard that holds the initial instructions so that the computer can boot up.
Let’s think about why we need ROM
The operating system is stored on the hard disk. The operating system holds the instructions for controlling the computer. When you first boot up a computer, RAM is empty. The computer has to be told how to get the operating instructions from the hard drive and place them in RAM.
ROM tells the computer how to do this.
ROM also holds instructions so that when the computer boots up it can carry out a Power On Self Test. It checks to see if a keyboard is present, if RAM is healthy and how much of it there is, how many hard drives there are and how big they are, if a floppy drive is present and working.