textfiles/computers/mrdos1.txt

IF YOU HAVE NEVER USED A COMPUTER BEFORE:

Welcome!  Computers have been around since the Chinese Abacus.
They are here to stay.  There is a certain feel and flow to the
logic which directs their activities.

Electronically all computers work about the same.  The one you
are using is called a MICROcomputer.  This is due to its size.
Larger computers include MINIcomputers and Mainframe computers.

RAM
---
Think of a computer as a human brain.  Your brain is a memory sponge.
It contains a lifetime of memories which cause us to act or react
based on inputs.  Inputs come via our 5 senses.  If you see and smell
a steak burning on the grill (inputs) you know how to react based on
previous experiences (memory - go out to eat).

The computer's brain is comprised of a large memory area called Random
Access Memory (RAM) and a calculating portion called the Central Processing
Unit (CPU).  The CPU and RAM work together as the computer's "brain".  Each
day when we start up the computer one of the first tasks will be to fill
RAM with instructions to give it an ability to perform work.  This work may
be in the creation of documents or tracking accounting data (more information
on CPU is found under the HARDWARE section).

You control which instructions will go into the computer's brain.
You control which sets of experiences you will provide the
computer.  Once in RAM, the computer will evaluate inputs from
many devices and react.  The most typical input device is a
keyboard.  As you type commands, the computer evaluates them and
based on the set of instructions within its RAM, will follow some
action - perhaps print a document, calculate, or send information
over a telephone line.

At some later point you may empty the computer's brain and
install a different set of instructions, thus giving it a
different ability.

Unlike a human, the computer requires electricity to keep the
information within RAM.  Each time the computer is turned off,
all information within RAM is lost.  RAM is a temporary memory.
To save instructions for use at a later date, a storage device is
required.  Computers use many such devices.  Your computer uses a
Floppy Disk and/or a Hard Disk.  Both are similar.

DISKS
-----
Think of these disks as cassettes.  You can record information on
a cassette which can be replayed indefinitely and if desired,
recorded over.  Floppy and Hard Disks operate in a similar fashion.
We record (Save) something we have created - like a document - onto the
disk.  Then, hours, days, or months later we are able to play back
(Retrieve) the document into the computer to alter or print out.  Just
like cassettes, the Floppy and Hard Disks do not require electricity to         





retain their information.

Hard Disks and Floppy Disks are similar.  Hard Drives have a larger
capacity for file storage, are faster and are less likely to fail due
to the protected environment from within which they operate.

RAM is called volatile memory because of the electricity
requirement.  Floppy and Hard Disks are called non-volatile
memory because they will retain their information without the aid
of electricity.

A computer system includes computer hardware, software and
people.  A computer is a device capable of solving problems
or manipulating data by accepting data, performing prescribed
operations on the data, and displaying the results.

HARDWARE versus SOFTWARE
------------------------
HARDWARE:  Physical equipment such as electronic,
magnetic, and mechanical devices (monitor, keyboard,
printer, microchip boards,...).  Includes INPUT/OUTPUT
DEVICES which allow the operator to communicate with the
computer and vice versa.

SOFTWARE:  Sets of programs (stored sets of
instructions) that govern the operation of computer system
and make the hardware run.  These programs (instructions)
tell the hardware how to perform a particular task such as
word processing, games, database management, etc.

Software refers to the instructions that are used to enable
an otherwise dead machine to understand your inputs and
transform them into desired outputs.

Computer hardware by itself has no personality; this is
determined by the software.  Word processing software turns
the computer into a word processor, accounting software turns
the computer into an accounting tool, etc.

The computer requires two types of Software:

  DOS - Disk Operating System
  Application Software - Word Processing, Spreadsheet, Games,
                         Database Management, Accounting, Payroll, etc.

DOS (Disk Operating System)
---
All computers require an operating system and the one IBM
PC's use is referred to as DOS (sounds like floss).  DOS is
software that allows the terminal, printer, computer and mass
storage systems (floppy disks) to work together as a unit,
and controls the execution of programs.  It also allows you
to perform housekeeping chores in regards to managing disks
and files.                                                                      







Therefore - DOS: 1. Links Hardware
                 2. Enables File Management


PROPER HANDLING OF DISKS  -  DISKS NEED CARE!
------------------------
 - Never touch the mylar surface  - Do not bend the disks
 - Always store in their protective sleeve
 - Hold the disk by its label or any part of the sleeve
 - Avoid bringing disks near magnets (TVs, telephones,..)
 - Do not leave in hot or cold areas (radiators, car-dash, in
   car during winter, etc.)
 - Use felt tip pens if possible when labeling.  Ball points
   can crease the mylar.

Note the write-protect notch on the disk.  If this is covered
by tape or non-existent, data cannot be "written" to the disk.
However, data can still be "read" from the disk.

It is a good idea to always save data and programs on two
separate disks in case one is destroyed.  Even with the most
cautious of care, the delicate Floppy Disks sometimes fail
for no apparent reason.


HISTORY:

The first computational device was the abacus.  This has been
in continuous use for thousands of years.  During the 1600's the
Pascal adding machine was developed.  This was a mechanical
device which laid the groundwork for today's odometers and
gas meters.  The 1800's saw many machines developed that were
controlled by punch cards - weaving looms, etc.  The
theoretical basis for electronic circuitry was developed in
the mid 1800's.

The first electronic computer was developed in 1942 at Iowa
State College.  From this point forth there were numerous
firsts as computers became less mechanical, smaller, faster
and cheaper.  IBM began dominating the computer market by the
mid-1950's and still does today in the mainframe (very large
computer installation) market.  Digital Equipment Corp.
(DEC) became a significant competitor by the mid-1960's.  DEC
is generally considered technically better (faster, smaller,
etc.) than IBM but still only has a fraction of the total
market due to marketing snafus.  Today the Cray Supercomputer
is the fastest in the world, is manufactured in Wisconsin,
and is set in a vat of liquid helium to increase the
conductivity for faster operation.
                                                                                





                     TIME vs SPEED

Method of Calculation             Approximate Speed
Human (manual calculation)        1 each 60 seconds
Burroughs E101 (1954)             4 per second
IBM 1130 (1964)                   600,000 per second
DEC PDP 11 (1974)                 1,000,000 per second
Cray supercomputer                13,000,000 per second

The Personal Computer is defined by its size, cost
applications for small business and the home.   The first one
appeared in January 1975 and was the Altair 8800 kit.  Only
hobbyist bought these.  Then the Radio Shack TRS 80 and Apple
computers hit the market as the first pre-assembled
microcomputers.

Market growth remained sluggish until two business students -
Dan Bricklin and Dan Fylstra developed a program to run on
Apple computers to handle the tedious recalculations in their
school assignments.  This program was called VisiCalc and is
the forerunner to the spreadsheet program Lotus 123.

With VisiCalc as a useful tool, Apple sales took off.  Apple
became the standard because all programs were written for
Apple.  Today we still see Apple dominate the school market.

In 1981 IBM introduced its PC which is unable to run Apple
software.  Unlike Apple or other IBM products, the IBM PC had
an open architecture which means the technical details of how
it operated were published right along with the product's
introduction.  This permitted hundreds of companies to write
software (programs) for the IBM PC as well as a variety of
accessories.  Adding IBM's sterling reputation, the open
architecture did enable rapid market penetration.  The
microcomputer was no longer a toy, it was a business tool.

The open architecture however, also allowed for the
generation of a host of lower cost compatible computers.
IBM had traded quick initial market entry for eventual erosion
of market share.  In both instances, we the consumers
benefit.


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