1. Computer Hardware
Part 2

2. Microprocessors popular microprocessors AMD and Intel are comparable
AMD (Advanced Micro Devices)
Motorola
AMD and Intel are comparable
Pentium 4
Itanium
Celeron
Athlon
Duron
The microprocessor that’s best for you depends upon your budget and the type of work and play you plan to do
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3. Random Access Memory
RAM (random access memory) - an area of the computer that temporarily holds data before and after it is processed
as you type, characters are held in RAM
It holds the data and the instructions for processing the data
It even houses OS instructions
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4. Random Access Memory RAM is primary storage (main memory)
Measured in megabytes (MB)
Today’s computers have between 64 and 512 megabytes of RAM
Amount of RAM depends on software you use
You can purchase additional RAM
A computer can use disk storage to simulate RAM. This is called virtual memory
Not as fast as RAM
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5. RAM components vary in speed, technology, and configuration
Speed is measured in nanoseconds. 1 nanosecond is 1 billionth of a second
It can also be expressed in MHz (millions of cycles per second)
Most computers use SDRAM (synchronous dynamic RAM)
Another type is RDRAM (Rambus dynamic RAM)
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6. RAM & Disk Storage
Capacitors are microscopic electronic parts that hold the electronic signals for the code that represents data.
charged capacitor = ON
discharged capacitor = OFF
each bank of capacitors holds eight bits
Disk storage is fairly permanent
Floppy disks, hard disks, or CDs
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7. Read-Only Memory
ROM (read-only memory) is one or more chips containing instructions that help a computer prepare to process tasks
ROM is permanent and non-volatile
Only way to change the instructions on a ROM chip is to replace the chip
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8. Read-Only Memory
Since RAM is empty when a computer is turned on, ROM BIOS is used
ROM BIOS (basic input/output system) is a set of instructions that tells computer how to access the disk drives and peripheral devices
Once operating system is loaded, the computer can understand your input, run software and access your data
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9. CMOS memory
A computer needs a semi-permanent way of keeping boot data, such as the number of hard disk sectors and cylinders
CMOS memory - holds data but requires very little power to retain its contents
Retains important computer settings after you turn the power off
can run by a battery on the motherboard
housed within the same chip carrier as ROM BIOS
Some computers have plug and play feature for updating CMOS
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10. Storage Devices
A storage device, such as a floppy disk drive, a hard drive, zip drive, and a CD-ROM drive, is used to store the data
A storage medium is the disk, tape, CD, DVD, paper or other substance that contains data
Storing Data
Retrieving Data
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11. Storage Technologies Magnetic storage
It stores data by magnetizing microscopic particles on the disk or tape surface
Read-write head - mechanism in the disk drive that reads and writes magnetized particles that represent data
Data stored on magnetic media such as floppy disks can be altered by dust, smoke, heat, and mechanical problems.
Some experts estimate that the reliable life span of data stored on magnetic media is about three years
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12. Storage Technologies Optical storage
It stores data as microscopic light spots (lands) and dark spots (pits) on the disk surface
Data stored on an optical storage device is less susceptible to environmental damage
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13. Which storage technology is best?
Versatility
can access data from different media
Durability
less susceptible to damage
Storage capacity - maximum amount of data that can be stored on a storage medium
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14. Which storage technology is best?
Speed - measured by access time and data transfer rate
Access time - average time it takes a computer to locate data and read it
millisecond = one-thousandth of a second
Random access - ability of a device to jump directly to the track or sector holding the data
floppy disk, hard drive, CD, DVD, zip disks
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15. Floppy disk Technology
A floppy disk is a round piece of flexible mylar plastic covered with a thin layer of magnetic oxide and sealed inside a protective casing
3 ½ diskettes have capacity of 1.44 MB
Other floppy disk types
ZIP disks – 100 MB and 250 MB
Superdisks – 120 MB
Disk density - closeness and size of magnetic particles it stores
Zip disks and Superdisks store data at a higher density than a standard 3 ½ floppy disk
Major advantage – portability
Major disadvantage – not a particularly speedy device and limited storage capacity
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16. Hard Disk Technology It provides lots of storage capacity
It provides faster access to files than floppy disk drives
It is economical
Hard disk platter - a flat, rigid disk made of aluminum or glass and coated with magnetic oxide
density far exceeds floppy disk
Hard disk - one or more platters and their associated read-write heads.
preferred type of main storage
A hard drive mechanism includes a circuit board called a controller that positions the disk and read-write heads to locate data
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17. Hard Disk Technology
Removable hard disk - hard disks that can be inserted and removed from drive
increase storage capacity
provides security for data
RAID - (redundant array of independent disks)
type of hard disk storage
found on mainframe and microcomputer installations
contains many disk platters
provides redundancy
faster data access
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18. Tape Storage
Tape
most popular form of storage in 1960s
Recent revival in tape storage for backing up data, not for principal storage device.
Tape backup - copy of data on hard disk stored on magnetic tape.
Requires sequential access
Inconvenient and slow
Data is arranged as essentially a long sequence of bits that begin at one end of the tape and stretches to the other
Tape drives are available in either internal or external models
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19. CD Technology CD-ROM stands for Compact Disc Read-Only Memory
data stamped on when manufactured
coated with clear plastic, durable
estimated life exceeds 500 years
inexpensive to manufacture
ideal for distribution of large files
A single CD-ROM holds up to 650 MB
It is very durable
Original CD-ROM had speeds of 150 KB per second
Today, speeds of 24x or higher (24 x 150 KB per second)
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20. DVD Technology DVD (digital video disc or digital versatile disc)
variation of CD technology
designed to provide enough storage capacity for a full length movie
will replace video tape (experts believe)
DVD-ROM disk (sometimes used for DVD-Video)
stamped with data when manufactured
cannot change or add data
stores 4.7 GB
ideal for games, maps, large databases
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21. Input/Output Devices
Data Bus carries data from one component to another
I/O (computer jargon for input/output) refers to collecting data and transporting results.
Expansion bus - the segment of the data bus that transports data between RAM and peripheral devices
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22. Input/Output Devices Peripheral Devices Display devices Printers
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