Lecture 1: Introduction to Computers and Programming Flashcards
A program is
A set of instructions that a computer follows to perform a task
Programs are commonly referred to as
Computer software
A programmer (or software developer) is
A person who designs, creates, and tests computer programs
The physical devices (or components) which make up a computer are commonly referred to as
Hardware
Some of the components that make up a typical computer
1) Central processing unit (CPU)
2) Main memory
3) Secondary storage devices
4) Input devices
5) Output devices
When a computer is performing tasks that a program tell it to do, we say that it is
Running or executing the program
The central processing unit (or CPU) is the part of
The computer that actually runs the programs
The computer sends coded instruction to the CPU, which perform the
Required operations (such as arithmetic and logic)
A computer’s main memory consists of a long list of
Memory locations
Each memory location holds a string of
0s and 1s
When a program is running, it is stored in
Main memory
Main memory is also called
Random access memory (or RAM)
Because the CPU can quickly access data from
Any random location in RAM
RAM is volatile (temporary) storage. When the computer is turned off, all data stored in
RAM is erased
Secondary storage holds data for long periods, even while the computer is
Off
Installed programs are always stored in
Secondary storage and are temporarily loaded into main memory when they are running
When we close Word and it is erased from
Main memory, it still exists in secondary memory
The most common type is the
Hard drive, although solid state drives are becoming more popular
Input: Data the computer collects from people and other devices. Common input devices
1) Keyboard
2) Mouse
3) Touchscreen
4) Scanner
5) Microphone
Output: Data the computer produces for people or other devices. Common output devices
1) Screen
2) Printer
3) Speaker
The program that tell a computer what to do are referred to as
Software
There are two general categories of software:
System software and application software
System software controls and manages the basic operations of a computer. The most common system software is the
Operating system, which controls the internal operations of a computer’s hardware and manages connected devices
Application software is any program a computer’s user runs to
Perform some task
All data stored in a computer are sequences of 0s and 1s, known as
Binary numbers
A single binary digit is called a
Bit
Main memory (RAM) is divided into billion of
Storage locations. Each location is large enough to hold a byte
A byte is a binary number made up of
8 bits
Each memory location can store a
Small number or a letter of the alphabet
A bit can be thought of as a light switch that can either be
“On” or “Off”
If a bit is 1 we say it is
On
If a bit is 0 we say it is
Off
Each storage location in main memory has a
Memory address, beginning with address 0
The computer uses a memory address to access the data in its
Storage location
The addresses and data are in binary, which is how
A computer stores data
Although computer only use binary, simplicity
1 will sometimes shows memory addresses in decimal and the data they contain in decimal and letters
In binary, all numeric values are written as series of
0s and 1s
Any piece of data stored in a computer’s memory must be stored as a
Binary number
To store a character in memory, we first convert it to a
Numeric code
The standard coding scheme used is
ASCII
A CPU can only understand instructions written in
Machine language
A program written in machine language is a set of instructions made up of only
Binary numbers
Each machine language instruction tells the CPU to perform a very simple task. Some examples
1) Read a piece of data from main memory
2) Add two numbers
3) Substract one number from another
4) Multiply two numbers
5) Move a piece of data from one memory location to another
6) Determine whether one value is equal to another
The CPU does nothing on its
Own
It follows the fetch-decode-execute cycle with the program (or programs) currently loaded in
Main memory
The next instruction to be executed is
1) Fetched from main memory
2) Decoded by the CPU
3) Then executed
When computer were new,
Assembly language was created as an alternative to machine language
Short words called
Mnemonics are used in assembly language to represent the instructions a CPU can follow
A program called an
Assembler takes assembly language code and translates it to machine language code
The computer’s CPU can then run the
Machine language program
Although assembly language allows us to avoid writing machine language, it still requires
The programmer to understand a lot about the CPU, and it also require a large number of instructions for even simple program.
Since assembly language is similar to machine language, it is called a
Low-level language
From the 1950s onward, many
High-level languages have been created
A compiler is a program that translates a high-level language program to a
Machine language program
The computer’s CPU can then run the
Machine language program
An algorithm is a sequence of
Precise instructions which leads to a solution
As we have seen, an algorithm does not have to be written in programming langugage, we can also describe it in a
Human language
