Lecture 02 hardware

Information Technology Concepts

Hardware: Input, Processing & Output

Presented by:Dr. Akhlas Ahmed

Lecture # 01Preston University

Hardware Components

Central Processing Unit Primary Storage (main memory;

memory) Secondary Storage Input Devices Output Devices

Hardware Components

Hardware Components

Control Unit Part of the CPU that sequentially

accesses program instructions, decodes them, and coordinates the flow of data in and out of the ALU, the register, primary storage, and even secondary storage and various output devices.

ALU Portion of the CPU that performs

mathematical and logical comparisons.

Hardware Components

Register High-speed storage area in the CPU

used to temporarily hold small units of program instructions and data immediately before, during and after execution by the CPU.

Primary Memory Part of the computer that holds

program instructions and data.

Hardware Components in Action

Step 1. Fetch instruction Step 2. Decode instruction Step 3. Execute the instruction Step 4. Store results


Step 1:

In the instruction phase, the computer’s control unit fetches the instruction to be executed from memory.


Step 2:

Then the instruction is decoded so the central processor can understand what is to be done.

Step 1 & 2 are called the instruction phase, and Step 1 & 2 are called the instruction phase, and the time is takes to perform this phase is called the time is takes to perform this phase is called the INSTRUCTION TIME (I-time).the INSTRUCTION TIME (I-time).


Step 3:

In the execution phase, the ALU does what it is instructed to do, making either an arithmetic computation or a logical comparison.


Step 4:

Then the results are stored in the registers or in memory

Step 3 & 4 are called the execution phase. The Step 3 & 4 are called the execution phase. The time it takes to complete the execution phase is time it takes to complete the execution phase is called the EXECUTION TIME (E-time).called the EXECUTION TIME (E-time).


After both phases have been completed for one instruction, they are again performed for the second instruction, and so on.

The instruction phase followed by the execution phase is called a MACHINE CYCLE.


Some central processing units can speed up processing by using PIPELINING.

Whereby the CPU gets one instruction, decodes another, and executes a third at the same time.

The Pentium processor, for example, uses two execution unit pipelines.

This gives the processing unit the ability to execute two instructions in a single machine cycle.

Processing & Memory Devices

Processing Characteristics and Functions

Machine cycle time is measured in: Microseconds (1 millionth) for slower

computers Nanoseconds (1 billionth) Picoseconds (1 trillionth) for faster

ones. MIPS (Millions of Instructions Processed

per Second)

Wordlength and Bus Line Width

Data is moved within a computer system not in a continuous stream but in groups of bits. A Bit (BInary DigiT) 0 or 1.

Therefore, another factor affecting overall system performance, particularly speed is the number of bits the CPU can process at any one time.


This number of bits is called the Wordlength of the CPU.

A CPU with a wordlength of 32 (called a 32-bit CPU) will process 32 bits of data in one machine cycle.


Data is transferred from the CPU to other system components via Bus lines, the physical wiring that connects the computer system components.

The number of bits a bus line can transfer at any time is known as bus line width.

A bus line with a width of 32 will transfer 32 bits of data a time.

Common wordlength and bus line widths are 32 and 64.

Memory Characteristics and Functions

Storage Capacity

Bill Gates made the famous remark…

“640 K ought to be enough for anybody..” 1981….

Things have changed drastically!

2004 –PC with 512 MB of Main Memory was standard….

Types of Memory

Types of Memory

Random Access Memory (RAM).

Dynamic RAM (DRAM). Synchronous DRAM

(SDRAM). SDRAM also has the

advantage of a faster transfer speed between the microprocessor and the memory.

Types of Memory

Read Only Memory (ROM) Programmable Read Only

Memory (PROM). Commonly used in video games.

Erasable Programmable Read Only Memory (EPROM). Commonly used with industrial robots and as a computer setup chip.

Read-Only Memory (ROM)

Erasable ROM (EEPROM): Flash memory Can be written to and erased Secondary storage /

Removable

Can be read but cannot be written to Nonvolatile BIOS

Cache Memory

Cache Memory is a type of high-speed memory that a processor can access more rapidly than main memory.

Cache Memory works in conjunction with main memory.

Cache Memory

A cache controller determines how often the data is used and transfer frequently used data to cache memory, then deletes the data when it goes out of use.

Multiprocessing

A number of forms of Multiprocessing involves the simultaneous execution of two or more instructions at the same time.

One form of multiprocessing involves coprocessors.

A Coprocessor speeds processing by executing specific types of instructions while the CPU works on another processing activity.

For example, math coprocessor chip can be used to speed mathematical calculations, and a graphics coprocessor chip decreases the time it takes to manipulate graphics.

Massively Parallel Processing

Parallel Processing, a form of multiprocessing that speed processing by linking several processors to operate at the same time, or in parallel.

Massively Parallel Processing

With Parallel Processing, a problem is divided into several parts.

Each part is “solved” by a separate processor.

The result from each processor are then assembled to get the final output.

Secondary Storage

Secondary Storage (Permanent Storage)

Secondary storage devices that store larger amount of data, instructions, and information more permanently than allowed with main memory.

Offers the advantages of nonvolatility, greater capacity, and greater economy

Access Methods

Sequential: records must be retrieved in order Devices used are called sequential

access storage devices (SASD) Direct: records can be retrieved in

any order Devices used are called direct access

storage devices (DASDs)

Devices

Magnetic tapes Magnetic disks RAID (Redundant array of

independent/inexpensive disks) Storage area networks (SAN)

Optical disks Digital versatile disks (DVDs)

Devices

Magnetic Disks are also coated with iron oxide; they can be thin steel platters (Hard Disk or Diskettes).

Hard Drives and Diskettes

Hard Drives Several magnetic

disks Read/write heads High storage

capacity Diskettes

Portable magnetic media

Types of Secondary Storage

Magnetic Tapes and Disks, Optical Disks, and CD-ROMs, and DVD’s are used to store data for easy retrieval at a later date.

Devices

Magnetic tapes (Common secondary storage medium, Mylar film coated with iron oxide with portions of the tape magnetized to represent bits.

Devices

Magnetic Disks are also coated with iron oxide; they can be thin steel platters (Hard Disk or Diskettes).

Devices

RAID (Redundant array of independent/inexpensive disks) is a method of storing data that generates extra bits of data from existing data, allowing the system to create “reconstruction map” so that if a hard drive fails, it can rebuild lost data.

RAID sub-systems duplicate data on drives. This process is called DISK MIRRORING.

Devices

SAN (Storage Area Network) uses computer servers, distributed storage devices, and network to tie everything together.

To increase the speed of storing and retrieving data, fiber-optic channels are often used.

Devices - Optical Disk Storage

Uses laser beam technology to read and write.

Optical Disks a rigid disk of plastic onto which data is recorded by special lasers that physically burn pits in the disk. CD-ROM (Compact Disk Read Only Memory) a

common form of optical Disks on which data, once it has been recorded, cannot be modified.

CD-W (CD-Writeable) an optical disk that can written upon but only once.

CD-RW (CD-Rewriteable) on optical disk that allows personal computer users to replace their diskettes with high-capacity CDs that can be written upon and edited over.

Devices

Digital Versatile Disk Player (DVD) look like CDs but have a much greater storage capacity and can transfer data at a much faster rate.

Additional Devices and Media

Memory cards (The PC memory card is like a portable hard disk that fits into PC Card slot.

Flash memory (A silicon computer chip that, unlike RAM, is nonvolatile and keeps its memory when the power is shut off).

Additional Devices and Media

Expendable Storage (Allow users to add additional storage capacity by simply plugging in a removable disk or cartridge. The disk can be used to back up hard disk data or to transfer large files to classmates.

Secondary Storage

Comparison of methods of secondary storage

Input and Output Devices

Input Devices

Personal computer input devicesKeyboard

(QWERTY)Virtual Laser

Keyboard

Virtual Laser Keyboard

Input Devices

Pointing and Selecting DevicesE.g., mouse, light pen, touch pad, touch screen, joystick, and eye-tracking device

Input Devices

Scanning Devices (Entering Batch Data) Scanner (Used for repetitive information)

a. Handheld scanner b. Flatbed scanner

Input Devices

Audio - sound that has been digitized

Voice Input Microphone Speech recognition Voice-to-text

software

Input Devices

Digital Video cameras (make it possible for people at distant locations to conduct videoconferences, thereby eliminating the need for expensive travel to attend physical meetings.

Input Devices

Point of Sale (POS) Devices Credit/Debit Card Reader

Biometric devices Read:

Fingerprints Face geometry

Input DevicesMagnetic Ink Character Recognition (MICR)

Device

Other Scanning Technologies

Text recognition software Optical character recognition (OCR) Optical mark recognition (OMR)

Output Devices

Display monitors

Output Devices

Display monitors CRT- Cathode Ray Tube The quality of Screen is often measured by

the number of horizontal and vertical pixels used to create it.

A larger number of pixels per square inch means a higher resolution, or clarity and sharpness of the image.

For example, a screen with a 1024 x 768 resolution (786432 pixels) has a higher sharpness than one with 640 x 350 (224000 pixels).

Output Devices

Display monitors The distance between one pixel on

the screen and the next nearest pixel is known as DOT PITCH.

The common range of dot pitch is from .25mm to .31mm.

The smaller the number, the better the picture.

Output Devices

Display monitors Monochrome (One of the three

colors: Gray, green, or amber). CGA (Color Graphic Adaptor) was

one of the first technologies to display color images on the screen.

SVGA (Super Video Graphics Array) displays are standard, providing brilliant colors and higher resolutions.

Output Devices

Display monitors LCD (Liquid Crystal Displays)

Flat Panel Displays that’s use liquid crystal organic, oil-like material placed between two polarizers to form characters and graphic images on a backlit screen.

Passive-Matrix displays, the CPU sends its signals to transistors around the borders of the screen, which control all the pixels in a given row or column.

Active-Matrix display, each pixel is controlled by its own transistor attached in a thin film to the glass behind pixel.

Printers and Plotters

Output Devices

Printers Daisy Wheel Plotters Dot Matrix

80 Columns 120 Columns

Ink Jet Laser Jet Computer Output

Microfilm (COM) Devices

Output Devices - Audio Output

Sound card and speakers Sound card translates digits into

sound Also used to capture sound

Other audio output E.g., USB headphones

Computer System Types

Supercomputers Typically use for

Scientific applications, marketing, customer support, product development).

Memory: 500+ GB


Mainframe Computers Typically use for large

general purpose business & Government computing need to meet the goals.

Memory: <100+ GB


Personal Computers

Handheld fitting on desktop, typically use to improve personal productivity of a worker

Memory: 512MB - 2GB

Computer System Types - Portable Computers

Notebook computers Light weight Battery powered Limited expandability Docking stations

Computer System Types - Tablet PCs

Type of notebook that accepts input from an electronic pen

a. Slate modelb. Convertible model

Computer System Types - Handheld Computers

Small computers that can be carried in a pocket

Niche in the portable computers market

Personal digital assistants (PDAs)

Cell phones Most popular manufacturers

RIM – Blackberry Palm – Treo

Lecture 02 hardware

Education

primary memory

memory characteristics

instruction time

flash memory

memory prom

memory eprom

processing memory devices

instruction phase