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This idea and some of the questions that follow are based on the concept material in the manual for Computer Science Course 103, © The University of Waikato , 2003 by Professor Ian H Whitten and others .
Since "the others" include me and "they" are still using "my" notes for the course I don't feel too bad about this :-)
This Applet simulates the physical card deck we use in our lessons. The Applet source code is here. If you have trouble seeing the Applet, download the free jre from http://www.java.sun.com or use the Flash Version (requires Flash Player)..
Make the sequence 0 1 1 0 1. The zero represents the card when it is face down and therefore whether the value of the card is to be counted. Therefore the binary number 01101 is equivalent to the decimal number 13.
The above represents decimal 22. Notice that by convention we usually show the leading zeroes in a binary number (although we don't usually write 000022 for decimals).
One advantage of this system is that we can subtract binary numbers by adding a negative one to a positive one. This is quite easily done with electronic circuitry.
Characters are often represented using ASCII (American Standard Code for Information Interchange). In this system, every character (even some that don't print) has its own binary code:
If we only want to represent two colours (black and white, say) we need only 1 bit per pixel:
0 0 0 0 0 0 0 0
The term byte refers to the standard grouping of 8bits into a single unit denoted by the single letter capital B .
Thus 4 Mb of memory is very different to 4 MB of memory.
In the decimal system, we often see the following measurements used:
Tera (T) 1,000,000,000,000
In computing the measurements such as K are slightly different to those shown above in the table since the computer operates on the binary system.
For example 1 KB = 1024 (2 10 ) bytes; often we use the term KB as an approximation for 1000
Tera (T) 240
Here is a link to the worksheet (pdf) we use with the cards.
Here is the same thing in Flash (in case of Applet trouble); opens in a new browser window.
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License. © 2001 - 2009 Richard Jones, PO BOX 246, Cambridge, New Zealand;
This page was last modified: October 28, 2013