1. CSCI 161: Introduction to Programming
Lecture 2:
computer History and Language Basics

2. Computer and Programming Basics
A computer is an electronic device that can perform certain tasks.
Hardware architecture: CPU, Memory, IO, Secondary Storage; Software (Computer programs) give instructions to computers to perform the tasks.
Computers use binary system, meaning that they essentially only understand 1 and 0.
Low Level Programming language
High level language: C Language is an example. Programs written in C has to be compiled to machine language so that computer can understand.
IDE: CodeBlock

3. A brief History of Computers

4. History of Computers
Modern computers result from 2 streams of evolution
Mechanization of arithmetic
calculating machines (hardware)
Concept of stored programs
process control (software)

5. Mechanization 1 The abacus Blaise Pascal (1623-1662)
used by the Chinese 3 to 4 thousand years ago
Blaise Pascal ( )
Pascal’s Adder
1st mechanized adding machine
gears and wheels
add and subtract, calculate taxes
inaccurate

6. Mechanization 2 Gottfried Wilhelm von Liebniz (1646-1716)
1670’s - Liebniz calculator
similar to Pascal’s design
add, subtract, multiply, divide
more reliable and accurate
still inaccurate
he also invented calculus

7. Stored Program 1 Joseph Marie Jacquard (1752-1834)
Jacquard’s Loom
weaving loom
metal punch cards to position threads for the weaving process
within the decade, 11,000 used in France
may have been 1st case of unemployment caused by automation

8. Stored Program 2 Herman Hollerith (1860-1929)
designed a machine that used electric charges to read info off of punch cards
for use in 1890 US census
store and process census data on punched cards
started his own company in 1896
in 1924 that company became International Business Machines Corporation or IBM

9. Charles Babbage (1792-1871) 1830-71 - Analytical Engine
Difference Engine
compute polynomials for math tables
abandoned, wasn’t precise
Analytical Engine
designed but never completed, ahead of its time
Mill - arithmetic computations
Store - store data and results
Operation cards - program instructions
Variable cards - select memory location for ops
Output - printer or punch cards

10. First Computers 1944 - Mark I John Atanasoff and
ABC
John Atanasoff and
Clifford Berry (Iowa State)
small scale vacum tubes
Mark I
electromechanical computer
Howard Aiken (Harvard U.)
first real analytical engine
based on relays

11. ENIAC - 1946 Electronic Numerical Integrator and Calculator
Best known as first fully electronic computer
18,000 vacuum tubes
1,500 relays
20 x 40 foot room
low reliability, lots of power, air conditioning
Grace Hopper
debugging it

12. von Neumann Architecture
John von Neumann (Princeton)
Developed stored program concept
both programs and data stored in same memory
Fetch decode cycle
Modern computers said to use von Neumann architecture

13. First programmer: Ada Agusta
Daughter of Lord Byron
Wrote about analytical engine
Designed several programs for it
Known as the first programmer
1970’s Dept. of Defence named its programming language Ada

14. Computer Generations 1st Generation - before 1960
vacuum tubes and relays ENIAC
2nd Generation
transistors IBM 7090
3rd Generation
integrated circuits or chips IBM 360
4th Generation - after 1980
large-scale integration - microprocessors

15. Review Questions What two streams do modern computer evolve from?
The name of the first fully electronic computer
What architecture do modern computers use?

16. Programming

17. High Level Languages 1842 - Ada Agusta - analytical engine
John Backus - FORTRAN
1958, 60, 64 - ALGOL, COBOL, BASIC
US Dept. of Defence - Ada
Nicklaus Wirth - Pascal
Dennis Ritchie - C
Nicklaus Wirth - Modula-2
ANSI C adopted
Java, Python ….

18. Software Development Early computers - complex coding schemes
machine language - 0’s and 1’s
Later on - introduction of system software
assembly language - mnemonics for operations
assembly program  assembler  machine lang
Even later - compilers created
high-level languages (HLL) - natural language
HLL program  compiler  machine language

20. HLL to Machine Language
Enter HLL program into file using editor
program.cpp - source file
Translate source code to machine code
program.obj - object file
Combine object code with libraries
program.exe - executable file

21. IDE Integrated Development Environment Note
combines editor, compiler, linker, loader
usually includes tools to assist in debugging
Note
IDE’s usually do not write to disk automatically
must remember to save work to disk often, especially before executing a program

22. First Program //library inclusion //function “main” //display string
#include <iostream>
using namespace std;
int main() {
cout << ”Hello world.”;
return 0; }
//library inclusion
//function “main”
//display string

23. Programming Errors Vocabulary and grammar - syntax
Rules determine if statement legally constructed - syntax rules
Compiler checks rules - gives syntax errors
Programs also contain errors in logic - bugs
Debugging - finding & fixing logic errors

24. A program to output the sum of two numbers