1. Standard Grade Computing LOW LEVEL MACHINE CHAPTER 21

2. Standard Grade Computing Input Process Output TaskInputProcessOutput Making toast Bread & electricity Heat from grilltoast Foundation

3. Standard Grade Computing Input Process Output TaskInputProcessOutput Making toast Bread & electricity Heat from grilltoast Boiling a kettle Water & electricity HeatBoiling water Foundation

4. Standard Grade Computing Input Process Output TaskInputProcessOutput Making toast Bread & electricity Heat from grilltoast Boiling a kettle Water & electricity HeatBoiling water Washing clothes Clothes, soap, water WashingClean clothes Foundation

5. Standard Grade Computing Input Process Output TaskInputProcessOutput Making toast Bread & electricity Heat from grilltoast Boiling a kettle Water & electricity HeatBoiling water Washing clothes Clothes, soap, water WashingClean clothes Doing homework Questions & text book Reading & thinking Answers Foundation

6. Standard Grade Computing DATA STORAGE UNITS Bit: Binary Digit i.e. 0 or 1 Byte:8 bits e.g. 0110 1100 Kilobyte (Kb):1024 bytes Megabyte (Mb):1024Kb (= 1024 x 1024 = 1 048 576 bytes) Gigabyte (Gb):1024Mb (= 1024 x 1024 x 1024 = 1 073 741 824 bytes) Terabyte (Tb):1024Gb (= 1 099 511 627 776 bytes) Foundation The main memory size of a computer is measured in megabytes or gigabytes. Extra memory can be bought and added to allow greater data storage.

7. Standard Grade Computing Data Representation Machine Code : is understood by computers and uses binary 0 or 1. NUMBERS are represented using binary (>0) General 1286432168421 24 00011000

8. Standard Grade Computing Data Representation 1286432168421 24 00011000 59 00111011 General

9. Standard Grade Computing Data Representation 1286432168421 24 00011000 59 00111011 94 01011110 General

10. Standard Grade Computing Data Representation 1286432168421 24 00011000 59 00111011 94 01011110 157 10011101 General

11. Standard Grade Computing Data Representation TEXT (ASCII) American Standard Code for Information Interchange Each keyboard character is represented by a unique binary code An 8 bit code is used e.g. A = 65 = 0100 0001 Understood by different text applications. Allows different computer systems to communicate successfully. General

12. Standard Grade Computing Data Representation Bit Mapped Graphics (B&W) Screen contains pixels Pixel either ON or OFF Coded using binary The example uses 8 bytes of storage i.e. 8 x 8 bits Increasing the resolution means more pixels 10000001 01000010 00100100 00011000 00011000 00100100 01000010 10000001 General

13. Standard Grade Computing Storage Requirements Bit Mapped Calculation Pixels = 2500 x 1000 = 2 500 000 pixels 1 pixel uses 1 bit of storage. = 2 500 000 bits /8 = 312500 bytes /1024 = 305 Kb Credit 2500 pixels 1000 pixels

14. Standard Grade Computing Processor Structure The processor is made up of 3 parts Control Unit: carries out program instructions in order ALU: does calculations & logical operations (decisions) Registers: temporary memory locations Credit INPUT DEVICES BACKING STORAGE DEVICES OUTPUT DEVICES MAIN MEMORY PROCESSOR COMPUTER SYSTEM

15. Standard Grade Computing And finally WORD: Number of bits sent to the processor during each fetch operation ADDRESSABILITY: All data is placed in storage locations. Each location has a unique address Credit

16. Standard Grade Computing The End Remember to view this slide OFTEN for good learning!