Introduction to Computers and Python

What is a Computer? Computer- a device capable of performing computations and making logical decisions at speeds millions times faster than humans. Computer Program- set of instructions that tells the computer what to do.

Computer Programmers The individuals that write programs for the computer. That’s what you will all be doing in this course.

Hardware- devises that make up the computer such as the keyboard, screen, mouse, disks, memory, CD-ROM, and processing unit. Software- The programs that run the computer. Current trend- as hardware costs drop the cost for software rises.

Computer Organization Six Logical Units 1. Input Unit- “Receiving Unit”. Section of the computer that obtains information. Types of Input Devises  Keyboard  Mouse  Microphone  Scanner  Digital camera

2. Output Unit- “Shipping” section. Section of the computer that takes information that the computer has processed and places it on various output devises Output Devises Monitor, printer, audio-visual devises.

3. Memory Unit “warehouse section”- temporarily stores data. The memory unit retains information that has been entered through the input unit. Often called RAM- Random Access Memory Volatile- erased when machine is turned off.

4. Arithmetic and Logic Unit. ALU “Manufacturing “ section- Responsible for the performance of calculations such as addition and multiplication. It also contains the decision mechanisms allowing the computer to perform such tasks as determining whether two items stored in memory are equal.

5. Central Processing Unit CPU “administrative section’ This section coordinates the operation of the other sections. Acts as the brain of the computer telling it to use the appropriate unit.

6. Secondary Storage Unit “long-term warehousing” This refers to the hard drive, disks, network or other places data is stored when not being actively used. Information in this type of storage takes longer to access than information stored in primary storage Not Volatile

Different Programming Languages Machine Language- the only language a computer can understand directly. Consists of a stream of numbers which are ultimately reduced to 0’s and 1’s This might be the machine code to add two numbers together Every machine has a different machine language

Assembly-used English like abbreviations to represent elementary operations of the computer. LOAD x,y ADD x + y Still different on every computer

High-Level Languages- a programming language in which single statements accomplish substantial tasks. Can be used on different computers Compilers work as translation programs converting high-level language to machine language. Sum= x + y

Python and other High- Level Languages Python was created from the start to be easy to learn. Python programs are about the easiest to read, write and understand. Python is free. Python is open source software. Any user can extend Python Used by thousands of professionals around the world including NASA and Google. Runs on different kinds of computers.

Other High-Level Languages  C, C++, Java, C#, Pascal, COBOL, FORTRAN  Structured Programming- designig programs so they are easy to follow and easy to modify. Went from general to more specific. Programs were broken into modules.

Questions Computers can only understand their native ______ language. Computers process data under the control sets of instructions called computer _______. Name the three types of languages discussed in this chapter. Programs that change high level language to machine language are called______.

Name two input and two output devises. Why is the CPU called the brain of the computer? What are the two types of operations performed by the ALU? In this class you will become____ programmers.