CS101 Students and Non-Computer Science Students Log On  Computer hardware components are the physical pieces of the
computer.
 The major hardware components of a computer are:
– The central processing unit (CPU)
– Main memory
– Secondary storage devices
– Input and Output devices
1-37
 Commonly known as random-access memory (RAM)
 RAM contains:
– currently running programs
– data used by those programs.
 RAM is divided into units called bytes.
 A byte consists of eight bits that may be either on or off.
 A word consists of 2 bytes.
0= 0
1= 1
2 = 10
3 = 11
4 = 100
5 = 101
6 = 110
7 = 111
8 = 1000
9 = 1001
10 = 1010
11 = 1011
12 = 1100
13 = 1101
14 = 1110
15 = 1111
16 = 10000
17 = 10001
18 = 10010
19 = 10011
20 = 10100
The earliest computers could only send 8 bits at a time, it was
only natural to start writing code in sets of 8 bits. This came
to be called a byte.
Binary computers motivate designers to making sizes powers
of two. Powers of 2 are magic (mathematically speaking)!
Since the &quot;standard&quot; character set required 7 bits
anyway(ASCII defined a 7-bit character set.), it wasn't much of
a stretch to add one more bit to get a power of 2.
The first widely adopted 8-bit microprocessor was the Intel
8080, being used in many hobbyist computers of the late
1970s and early 1980s, often running the CP/M operating
There are 28 (256) possible values for 8 bits. So what is
1011 anyhow?
(1 * 2^3) + (0 * 2^2) + (1 * 2^1) + (1 * 2^0) = 8 + 0 + 2 + 1 =
11
• Secondary storage devices are capable of
storing information for longer periods of time
(non-volatile).
• Common Secondary Storage devices:
• Hard drive
• CD ROM
• Floppy drive
• DVD RAM drive
• CD RW drive
• Compact Flash card
• Input is any data the computer collects from the
outside world.
• That data comes from devices known as input
devices.
• Common input devices:
– Keyboard
– Mouse
– Scanner
– Digital camera
• Output is any data the computer sends to the outside
world.
• That data is displayed on devices known as output
devices.
• Common output devices:
– Monitors
– Printers
• Some devices such as disk drives perform input and
output and are called I/O devices (input/output).
• Software refers to the programs that run on a
computer.
• There are two classifications of software:
– Operating Systems
– Application Software
• An operating system has two functions:
– Control the system resources.
– Provide the user with a means of interaction with
the computer.
• Operating systems can be either single tasking
• A single tasking operating system is capable of
running only one program at a time.
– DOS
• A multitasking operating system is capable of running
multiple programs at once.
– Windows
– Unix
– Mac OS X
• Operating systems can also be categorized as
single user or multi-user.
– A single user operating system allows only one user
to operate the computer at a time.
– Multi-user systems allow several users to run
programs and operate the computer at once.
• Application software refers to programs that make the
computer useful to the user.
• Application software provides a more specialized type
of environment for the user to work in.
• Common application software:
–
–
–
–
–
Word processors
Accounting software
Tax software
Games
• A program is a set of instructions a computer follows
in order to perform a task.
• A programming language is a special language used to
write computer programs.
• A computer program is a set of instructions that enable
the computer to solve a problem or perform a task.
• Collectively, these instructions form an algorithm
• An algorithm is a set of well defined steps to
• The steps in an algorithm are performed sequentially.
• A computer needs the algorithm to be written in
machine language.
• Machine language is written using binary numbers.
• The binary numbering system (base 2) only has two
digits (0 and 1).
• The binary numbers are encoded as a machine
language.
• Each CPU has its own machine language.
– Motorola 68000 series processors
– Intel x86 series processors
– ARM processors, etc.
• Example of a machine language instruction:
1011010000000101
• In the distant past, programmers wrote
programs in machine language.
• Programmers developed higher level
programming languages to make things easier.
• The first of these was assembler.
• Assembler made things easier but was also
processor dependent.
Programming Languages
• High level programming languages followed
that were not processor dependent.
• Some common programming languages:
Java
C
Visual Basic
BASIC
C++
Python
COBOL
C#
Ruby
Pascal
PHP
JavaScript