TexPREP Summer Camp
All those parts of a computer that you
can see and touch.
Programs (set of instructions) and
The two most important components of a
• CPU: Central Processing Unit
• Memory: typically RAM (Random Access
They are connected by the system bus and are
located on the motherboard.
The CPU is the “brain” of the computer.
• It gets an instruction from main memory and then executes
• If the instruction needs some data, it gets the data from
main memory in order to process it.
• After executing the instruction, if there is a result that
needs to be saved, it stores the result on main memory.
These steps are repeated for each instruction in the program.
The speed of the processor is expressed in Gigahertz (GHz).
There are different types of memory in a computer system.
• Main memory (RAM): where programs and data must be
loaded in order to be processed.
• ROM: where the boot (startup) program is stored.
• Cache: very high speed memory used to improve the
performance of the system.
The amount of memory is typically expressed in Megabytes (MB),
Gigabytes (GB), or Terabytes (TB).
RAM and Cache are volatile, that is, they lose their content when the power is
turned off. ROM is not volatile.
Their access time is in the order of nanoseconds (0.000000001 seconds)
The components of the computer must interact
in a synchronized way.
A system clock is used to control the timing of all
It generates regular “ticks” (electronic pulses)
that set the operating pace of the
Its speed is expressed in Megahertz (MHz) or
• Storage devices: used to store data and programs
permanently (non volatile). For example: hard drive,
flash drive, cd drive, etc.
• Input devices: used to enter data and instructions
(programs, commands, etc.) into the computer. For
example: keyboard, mouse, microphone, scanner,
• Output devices: used to get information from the
computer. For example: monitor, printer, speakers,
The three main technologies are:
• Magnetic: used on hard disks, tape, etc.
• Optical: used on CDs (ROM, R, RW), DVDs (R, RW,
• Solid state: used on flash drives, memory cards,
shines a light
If light strikes
a pit, it scatters.
If light strikes a
land, it is
light- reflected back
sensing toward diode.
Discovering Computers 2006, Course Technology, p. 367 Fig. 7-20
Reflected light is
deflected to a
which sends digital
signals of 1 to
of reflected light is
read as digital
signal of 0.
Also known as expansion boards, are used to
increase the capabilities of a computer.
They must be inserted in expansion slots and
their respective device drivers installed before
they can be accessed by the system.
There are different technologies: PCI, AGP, etc.
Adapter Cards examples
• video adapters
• graphics accelerators
• sound cards
• accelerator boards
• NIC - network interface card
Graphics Adapter Card
Units of measurement
KILO: 1,000 or 103
MEGA: 1,000,000 or 106
GIGA: 1,000,000,000 or 109
TERA: 1,000,000,000,000 or 1012
Inside the computer…
Everything is discrete (digital), not
continuous (analog) – i.e, it must be
represented using a discrete (number)
Problem: How do we put the analog
world “inside” the digital computer?
Solution: Devise ways to represent
real-world, analog data in digital forms
What do computers work with
Computers have storage units called binary digits or bits
The computer operates with voltage through what
amounts to microscopic switches that are either “On” (1)
or “Off” (0)
Low Voltage = 0
High Voltage = 1
all bits have value 0 or 1
Binary number system
ASCII (American Standard Code for Information
Interchange) and Unicode