PC Hardware
Grade 9
PC Hardware Outline
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What is a computer?
What are examples of computers?
What types of PCs exist?
What is the typical PC hardware?
How might we evaluate a PC?
– In terms of Speed…
– In terms of Storage Capacity…
– In terms of Memory…
Four Primary Functions of a Computer
• Input
• Process
• Output
• Store
Types of Computers
• Supercomputer
• Server
• Embedded Computer
• Personal Computer
Supercomputer
Server
Embedded Computers
Personal Computers (PCs)
Types of PCs
• Desktop
• Laptop
• PDA
• Tablet PC
Computer Hardware
• Computer hardware can be classified in
relation to the four primary functions of a
computer (discussed earlier):
– Input devices
– Output devices
– Processing devices
– Storage devices
Sample Classification
How are humans like a computer?
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Input devices?
Output devices?
Processing devices?
Storage devices?
How are humans like a computer?
• Input devices?
– Hands, Ears, Eyes, Nose, (Our senses)
• Output devices?
– Mouth, Hands, (Talking, writing, typing, etc)
• Processing?
– Brain
• Storage?
– Short term memory
– Long term storage
The human computer
Long Term Storage!
Short Term Memory!
Processing Information
Output
Output
Typical Desktop PC Hardware
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Central Processing Unit (CPU)
Motherboard
Random Access Memory (RAM) modules
Hard Drive
Keyboard
Mouse
Monitor
Power supply, case, etc.
Typical Desktop PC Hardware
Computer Part
• CPU
• Motherboard
• RAM modules
• Hard Drive
• Keyboard
• Mouse
• Monitor
• Power supply, case, etc.
Category
• Processing device
• Processing device
• Storage/Processing device
• Storage device
• Input device
• Input device
• Output device
• N/A
Consider editing a document on a PC
• When you type a letter on the keyboard, it is sent to the CPU
as input.
• Your input travels through the motherboard and is stored in
RAM. The RAM is short-term memory that holds programs
and data you are using.
• The CPU processes your input as a document character and
updates the output on the monitor to show the new character
that you typed.
• Finally, when you save the document the information is stored
for the long term on the hard disk drive.
A closer look at a motherboard…
Motherboard
Ports
Evaluating a computer
• Speed
– How fast can my PC process information?
• Memory Capacity
– How many programs can my PC use at once?
• Storage Capacity
– How many files can my PC save?
• Other components:
– Can I watch DVDs? Can I play video games? Can I
connect my MP3 player?
Evaluating a computer
• Speed
– CPU speed
• Memory Capacity
– RAM size
• Storage Capacity
– Hard Drive size
• Other components:
– Ex: Floppy drive, CD-ROM, DVD-RAM, video card,
USB ports
CPU speed
• Measured in Hz (Cycles per second)
• CPU processes data during each cycle
• Early PCs ran at speeds such as 2MHz or 2,000,000 cycles per
second:
– 1 Hz = 1 cycle per second
– 1 MHz = 1,000,000 Hz
– 1 GHz = 1,000 MHz or 1,000,000,000 Hz
• Modern PC CPUs are typically between 1GHz and 3GHz
CPU speed
Input
The CPU cycle:
Output
Each cycle this
process repeats!
CPU
Before we talk about memory:
• ROM vs RAM
– ROM = Read Only Memory
• Can only read contents, can’t write them
– RAM = Random Access Memory
• Can read or write to memory
• Volatile vs Nonvolatile
– Volatile = Memory is lost if power goes out
– Nonvolatile = Memory is more permanent
How much is a byte?
Name
Abbr. Num. Bytes
Relative Size
Byte
B
1 byte
1 character
Kilobyte
KB
1,024 bytes
¼ typed page
1,048,576 bytes
1,073,741,824B
768 pages
786,432 pages
Megabyte MB
Gigabyte GB
Storage Capacity
• In these slides I’m referring to the Long Term storage
of a computer.
• This is the memory used to store files and programs
for future use.
• In PCs, the internal hard drive is typically used for
long term storage.
• More Hard Drive space = More files you can store
Storage Capacity
Medium
Capabilities
Capacity
Hard Drive
RAM
External: up to 2TB
Internal: up to 500GB
CD / CD-RW
ROM / RAM
700MB
DVD/DVD+RW
ROM / RAM
4.7GB to 9.4GB
Flash Cards
RAM
16MB to 8GB
Floppy Disk
RAM
1.44MB
Flash Drive
RAM
Up to 6GB
Memory Capacity
• In these slides I’m referring to the Short Term storage
of a computer.
• This is the memory used to hold programs and data
while your computer is running.
• In PCs, the RAM is typically used for short term
storage.
• More RAM space = More programs you can run at
once.