Session 5 Lesson Plan Computer Systems
Intro to Session
Data Representation Number system to include ASCII, bit masks and graphic bitmaps. Conversion to/form ASCII
Ones Complement
3 = 00000011
as ones complement change all ones to zeros and zeros to ones
-3 = 11111100
Floating point
0.000123 wastes the zeros - all the zeros function is is to state where is the decimal point.
Therefore we normalise the number.
0.123 - the normalised mantissa and the exponent -3
0.123 x 10-3
BCD (Binary Coded Decimal)
What is BCD? Converting each number of a decimal to Binary - digit by digit.
1243 Convert 1 to Binary 2 to Binary and 4 to Binary 3 to Binary
Therefore 1243 becomes 0001 0010 0100 0011
ASCII Tables
ASCII American Standard Code for Information Interchange
We need to encode 26 letters of the alphabet for both upper and lower case plus the ten numeric symbols and about 20 or so special characters like the plus sign. This is easily done in 7 bits which gives 128 possible combinations. The ASCII code is usually encoded with 8 bits. This leaves one bit to be used as a parity bit.
Homework
Health & Safety Checks/Materials and equipment required:
Risk Assessment
Mobile White Boards
Materials
Multimedia Projector
White Board / Pens / White board cleaner / White board eraser
Computers with Windows XP, Dreamweaver, Fireworks, Flash, MS Project
Student mini white boards and pens
Previous learning assumed:
Knowledge of: DB, VB, Web, Spreadsheets from year 1 syllabus.
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