We Do Windows (and some Mac)

Understanding Computer Operating Systems

Osher Lifelong Learning Institute
University of Illinois, Urbana-Champaign

Scott Badman, Instructor

Session 1: Operating System Fundamentals and Data Storage

September 10, 2014



Computers and Operating Systems

Binary Arithmetic
Counting in Binary
Decimal Addition Table
Binary Addition Table
Computer Components
Byte - Unit of eight 1's or 0's
A byte's address - every byte is numbered in a simple way from 0 to how much memory you have (currently in the low billions)
Stores both program and data in the form of binary numbers.
Central Processing Unit (CPU)
Essentially a simple calculator that presses it's own buttons.
A very simplified computer calculating how many nickels are in 14 cents (as .pdf file) (as a Power Point presentation, large file and long download)
Important things to look for:
1. Multiple data values are stored in memory, something a simple calculator does not do.
2. The program is stored in memory as binary numbers representing which buttons to press.
3. The computer runs the series of button presses automatically -- something a human would have to do with a simple calculator.
4. A program has the ability to jump to another part of the program depending on the comparison of two numbers -- something a simple calculator can't do.
5. The ability to jump to another part of the program enables
decisions (for example: if x > 5 jump to another section of the program, otherwise just keep going)
and repetition (for example: if x > 5 repeat the part of the program that was just done)

Without a program to run, a computer is just useless hardware.

General Purpose Computers versus Special Purpose Computers
No difference in how they work internally.
General purpose computers have more expandability, especially for input and output. Examples: Desktops and laptops.
Special purpose computers have little or no expandability and fixed input and output. Examples: GPS receivers, engine computers in cars, SiriusXM radios.
The operating system of a special purpose computer is customized for the exact inputs, outputs, and specific purpose of the computer.
Memory in a special purpose computer is usually solid state electronic chips that retain data when they are turned off; rarely disk drives.
Some computers are blurring the line between general purpose and special purpose. Examples: Smartphones and tablets.
Operating System
The most fundamental program on the computer that is always running and allows a user to interact with the computer and to run other programs.
Modern Operating Systems preform these functions:
All input and output, including interacting with human users.
Run all programs, apparently concurrently using very quick time slicing.
Installing programs and peripherals.
Manage the computer's memory.
Starting itself during booting, and configuring itself for that specific computer.
Progression of Operating Systems
1940's - The first computers came with no programs at all - the buyer had to write every program from scratch.

Early 1950's - Mainframes come with simple Job Control Programs.
Ran programs automatically, one at a time.
Programs were stacks of punched cards or punched tapes.
Allowed queueing of multiple programs.
Data usually output as punched cards or sprocket driven printed paper.
Mid to Late 1950's - Early Disk and Tape Operating Systems.
Ran programs from magnetic disks or tape drives.
Stored data on magnetic tapes or disks.
Programs included instructions to the operating system to do input and output, instead of doing it directly.
The operating system could load multiple programs into memory and run them in tiny slices, quickly switching back and forth.
Early to mid 1960's - Projects such as Multics and IBM's Sabre Airline Reservation System.
The operating system allows multiple users to input data into a program from dedicated terminals.
1970 - UNIX
Highly innovative and influential operating system that has become the basis of almost all current operating systems.
Developed at ATT's Bell Labs by Ken Thompson, Dennis Ritchie, and Brian Kernighan.
Developed for a small (at the time) "mini-computer".
Real time, command line interface from a terminal.
Made the current mainframe operating systems at the time seem inefficient and hard to use.
The name is a satirical reference to the Multics project, which had become a large, unwieldy program for its time.
Late 1970's and early 1980's - Early microcomputer disk or tape operating systems, including Microsoft DOS
Single user, single-program-at-a-time operating systems that used many of the ideas of UNIX.
Allowed programs complete control of the computer
Anyone could write programs to run with the operating system.
The Super Bowl, January 22, 1984 - MAC OS
First popular Graphical User Interface with required mouse.
Multiple programs running at the same time with integrated look and feel.
Written from scratch for Apple MacIntosh hardware only.
Highly proprietary (i.e. secret) programming code.
Will only run Apple approved programs.
Late 1980's to early 2000's - Microsoft Windows 3.1, Windows '95, Windows '98, Windows ME
Programs that ran on top of single program Microsoft DOS to allow the illusion of true multi-program Graphical User Interface.
Very popular because they maintained compatibility with old Microsoft DOS programs. Businesses in particular wanted that compatibility.
Very prone to conflicts between programs, data corruption, and crashes.
1991 to present - Linux
A free version of UNIX, that anyone can use and modify.
Command line interface with possible Graphical User Interface programs similar to early Windows.
Beloved by techies, researchers, and computer professionals because of its power and adaptability.
Used as back-office Internet servers and corporate file servers because of its power, efficiency, and stability.
Disliked by casual users because of the same reasons -- you generally need to be a techie to install and run it well.
Surprisingly secure for an open-code operating system because of it's simple, robust design.
Mid 1990's to present - Microsoft Windows NT, Windows 2000, Windows XP, Windows Vista / 7, Windows 8.1
Written from scratch, true multi-program, Graphical User Interface, operating system.
The most useful operating system because of the number of programs available and its almost universal availability. Increasingly robust and secure.
Still, however, the least secure of all major operating systems.
2001 - present - MAC OS X
Complete re-write of MAC OX based on Unix.
Retained almost all of the advantages of the old MAC OS versions 1 to 9.
Still proprietary (i.e. secret) programming code, but easy and familiar for UNIX professionals to use.
Still extremely secure.
Greater compatibility with Microsoft files and data.
2007 - Smart Phone Touch Screen Based Operating Systems
iPhone first widely adopted example.
Intuitive Interface with much reduced on-screen choices.
More diversity -- still no dominant company, as IBM was for mainframes and Microsoft was for Personal Computers.
Designed for security from the beginning. Generally successful results.
Apple iOS
Firefox OS
Palm OS
Windows Phone and Windows Mobile

(10 to 15 Minute Break)

Practical Tips and Techniques

Where's My Data?

Survey of class interest in various operating systems.

Storage - Disk Drives.
Hard Disk Drives - HDD's
Solid State Drives - SSD's
USB Flash Drives (also called Thumb Drives)
Disk Drive Organization
Windows drive organization by drive letter
Use of backslash to separate directories
C:\Users\your_user_name\My library_name
MacIntosh drive organization by a single virtual drive called "root"
Use of forward slash to separate directories
Libraries are virtual directories that can look like they hold other directories and files.

Both Windows and Mac have similar libraries:
Videos (Windows) or Movies (Mac)
Public (handled a little differently in Windows and Mac)

Windows Libraries

Adding files:
Dragging and dropping into a library sometimes makes a copy, and sometimes makes a shortcut, depending on where it is coming from.
It is best to use libraries for all your files and avoid using other disks or directories,
or avoid libraries altogether and store your files in specific directories that you create on a disk.
MacIntosh Libraries

Adding files:
Simply drag and drop into your libraries.
It is probably best on MacIntosh to always use the supplied libraries.
Storage on an External Disk Drive (Windows and Mac)
Almost all external disk drives of any type now have a USB connection -- simply plug it in and both Windows and Mac automatically install it.
Cloud Storage and Synchronization
Follow whoever's cloud storage procedures you are using:

Amazon Cloud Storage, oriented toward Kindle products
Apple iCloud, oriented toward Apple products
Google Drive, generous free storage, available for most operating systems
Microsoft OneDrive, particularly used by Windows 8, but available for most operating systems
Numerous independent smaller companies

We Do Windows, Understanding Computer Operating Systems, Fall 2014, Osher Lifelong Learning Institute, University of Illinois at Urbana-Champaign