Technology Component: Computer Hardware – Part 2 Basic Components

Dr. V.T. Raja

Oregon State University

Basic Components of Hardware

• Input Devices• Processor/Central Processor/Chip

– CPU/ALU– Primary Storage

• Secondary Storage• Output Devices• Communication Devices (to be discussed

later in another chapter)

Processor

• Processor (Chip) has CPU and Primary Memory

• CPU does all the processing work in a computer

• Primary memory stores data and instructionsInstruction: A command that tells a computer how to

accomplish a given task

• CPU has Arithmetic Logic Unit (ALU) and Control Unit

• Control Unit accesses data and instructions from Primary Memory, and transfers them to ALU

• ALU performs basic arithmetic and logical operations

Types of Primary Memory: ROM and RAM

• ROM– PROM– EPROM

• RAM– SIMM– DIMM– SDRAM– RDRAM

• ROM stores some basic instructions permanently

• ROM is non-volatile

• RAM acts as a temporary storage for data and instructions

• RAM is volatile• RAM size commonly

expressed in MB or GBe.g,. 256 MB RAM;

2 GB RAM

Types of Primary Memory: Cache Memory

• Cache memory is a temporary storage for frequently used information

• CPU searches cache memory for data and instructions before it searches RAM

• Cache is typically located closer to CPU than RAM

• Bigger the cache, the faster the computer will perform (assuming all other factors are constant)

• Cache is volatile

Terminology

• What is clock speed?– Speed at which the processor completes machine cycles– Measured in Megahertz (MHz) or Gigahertz (GHz)

• Mega: Million; Giga: Billion– Hence, terminologies such as Pentium 4 / 3.2 GHz

• What is word length?– Number of bits that the processor processes at one time. – Example: 16-bit, 32-bit, 64-bit chips

Terminology

• What is data bus width?– The number of bits that can be moved at one time between the

CPU, primary memory and other devices of a computer.

• Which would you select?A 16-bit chip with a 16-bit data bus width (or) a 32-bit chip with a 8-bit data bus width?

• Factors affecting speed of a computer are:– Clock Speed

– Word Length

– Bus Width

Input Devices

• Examples of input devices?• What is Source Data Automation (SDA)?• Examples of SDA?• What are some advantages associated with SDA?

Storage Devices

• Examples of secondary storage?

• Typical storage capacity of secondary storage devices