BT 1005 Managing Information Lecture 2 Data Representation, Storage and Transmission

Contents Processing Evolution Data Representation Components Networks Summary

Processing Evolution Vacuum Tube – 5,000/100,000 cps Transistors – 250,000 cps Integrated Circuits Silicon Chips – 3/5 million cps –Digital Circuits Still (basically) switches

Data Representation Binary language Bits Bytes ASCII code

Components CPU (Central Processing Unit) Primary Storage Secondary Storage Input Devices Output Devices Communications Devices

CPU The Control Unit The Arithmetic Logic Unit Register Storage Area Processing power (clock speed) –GHz Gigahertz: a thousand million (billion) cycles per second Until recently measured in megahertz (MHz)

Primary Storage RAM (Random Access Memory) –Volatile ROM (Read Only Memory) –Permanent –OS for example Physically close to CPU Working area for data and instructions

Secondary Storage Hard Drives (Measured in Gigabytes/Petabytes) –A gigabyte equals about 2.3 million pages of text about the length of your final year dissertation! Magnetic Disk Optical Disk –CD (-R and RW) – 700Mb –DVD (-/+R and RW) – 4.5Gb HD and Blu-ray (Blue laser technology) – x3 capacity Magnetic Tape Flash Drives/Cards

Input Devices Keyboard Pointing Devices –Mouse –Touch screen Source Data Automation –Voice Input –Digital Scanner (OCR) –Barcode reader –RFID

Communication Devices Multi-core Cable –Twisted-pair vs Coaxial Fibre Optic Cable Radio Link Laser Link Advantages and disadvantages to each

Output Devices Cathode Ray Tube Digital Screen Printer Voice Output

Computer Networks Distributed Processing vs. Centralised Processing Client / Server Computing

Summary The format of data has evolved with each technology but remains basically the same Various methods exist to input, transmit and present output Telecommunications technologies allow for networks to span continents