1. Topic 1: Introduction to Computers and Programming
“A journey of a thousand miles must begin with a single step.” - Lao Tzu

2. Introduction to Computer Organization
Computers are composed of two distinct components:
Hardware – the equipment used to perform computations. This includes the CPU, memory, hard disk, etc…
Software – the programs that determine the operations to be performed by the hardware.
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3. Hardware Components Hardware consists of many types of components:
Primary Storage
Secondary Storage
The Central Processing Unit (CPU)
Input Devices
Output Devices
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4. Primary Storage and Secondary Storage
There are two primary types of storage in a computer:
Primary Storage – often referred to as main memory, or just memory. This storage is very quickly accessed by the various hardware components.
Secondary Storage – includes such devices as a hard disk, floppy disk, CD-ROM, DVD-ROM, etc…
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5. Memory Organization
Computer memory is organized into memory cells. Each cell has a unique address, which allows the accessing of each cell individually.
Programs are transferred from secondary storage into primary storage before they can be run.
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6. The Central Processing Unit (CPU)
The CPU is responsible for coordinating all computer operations and performing the operations specified in a program.
The CPU fetches an instruction from a program loaded in memory, decodes the instruction, retrieves necessary data, performs the operation, and then saves the result.
The CPU contains very high speed memory cells termed registers, which holds the data being operated on.
CISC 105 – Topic 1

7. Input and Output Devices
Input devices are used to communicate from some external source to the computer. They include the keyboard and the mouse.
Output devices are used to communicate from the computer to some external source. They include the monitor and the printer.
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8. Computer Software All major computers run an operating system.
An operating system is a special type of program which controls the interaction between all hardware components and the user.
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9. Operating Systems Tasks
Responsibilities of the OS include:
Communicating with the user(s)
Managing resources including memory and processor time among programs
Collecting data from input devices
Providing data to output devices
Accessing data from secondary storage
Writing data to secondary storage
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10. Binary Math
A binary digit or bit for short is the smallest unit of computer information. Just as our familiar decimal number system has 10 digits,(0,1,2,3,4,5,6,7,8,9) the binary number system has only 2 digits (0,1). This is the perfect number system for computers since we can store a binary digit by making an electrical or magnetic field either on or off, positive or negative, 1 or 0. In the decimal system we can count 10 (we start counting with 0) items with one decimal place, 100 with two decimal places, 1000 with three decimal places and so on.
CISC 105 – Topic 1

11. Binary Math
The binary number system works the same way except since we only have 0s and1s our base is 2.
So we can count 2 permutations of 1 bit: 0 1
4 permutations of 2 bits:
8 permutations of 3 bits:
16 permutations of 4 bits:
...and so on.
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12. Binary Math
So in an eight bit byte, the numbers are represented this way:
Bit:
Value:
Example:
Values: = 182
The minimum number is 0 (all 0s) and the maximum number is 255 (all 1s), so you can represent 256 numbers (0-255) with one byte.
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13. Computer Programming - Machine Language
Computer programs were originally written in machine language. Machine language is a sequence of binary numbers, each number being an instruction.
Each instruction is computer-understandable.
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14. Computer Programming - Assembly Language
To make machine language more abstract, assembly language was introduced.
Assembly language provides a one-to-one mapping between a machine instruction and a simple human-readable instruction.
CLR A
ADD A
ADD B
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15. Computer Programming – Assembly Language
Assembly language is converted to computer-understandable machine language by an assembler.
Although assembly language is much more clear and understandable than machine language, it is still very difficult to program.
The assembly code for the sqrt() function in C is composed of hundreds of assembly instructions.
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16. Computer Programming – High-Level Languages
In order to get around these obstacles, high-level languages were introduced.
High-level languages provide a one-to-many mapping between one high-level statement and multiple assembly language instructions.
High-level language is converted to assembly instructions by a compiler.
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17. Computer Programming - Compilation
A = 6 X 3
MOV EAX, 0 // initialize EAX to 0
MOV EBX, 3 // set multiplicand
LABEL1:
ADD EAX, 6 // multiplier
DEC EBX // decrease count
JNZ LABEL1 // loop if need to
STOR A, EAX // store result in A
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18. Modern Software Development
Modern software development is done in high-level languages, with few exceptions.
High-level language is first compiled from source code to assembly and then assembler into machine code. Modern compilers perform the assembler function as well.
Compiled source code is called an object file.
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19. Modern Software Development
Programmers often use library functions, which are pre-written functions provided as part of the compiler/development toolset.
A library is an object file.
After the source code is compiled into machine code, a linker resolves cross-references among these object files, including libraries. The object files are linked into an executable file.
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20. Modern Software Development
The executable file can now be run.
The operating system loader loads the executable file into memory and schedules the program for execution.
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21. Modern Software Development
Compiler
Source Code File
Object File
Other Object Files
(perhaps libraries)
Linker
Executable File
Loader
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22. The Software Development Method
Specify the problem.
Analyze the problem.
Design an algorithm to solve the problem.
Implement the algorithm.
Test and verify the program.
Maintain and update the program.
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23. Review Name the principle components of a computer.
What are three responsibilities of the operating system?
What advantage does assembly language have over machine language?
What advantages do high-level languages have over assembly language?
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24. Review
What computer program translates a source code file into an object file?
What program combines object files and produces an executable file?
What part of the operating system is responsible for the loading and scheduling of programs?
What are the steps in the software development method?
CISC 105 – Topic 1