Followers

Thursday 23 December 2010

Robotics

Robotics are now beginning to be used in everyday life, from travelling to space and back, to building machines such as cars and computers.

Strengths - They are resistant to heat, pressure, pain, and radiation e.g. Submersibles
               - Perform repetitive tasks without boredom or errors e.g. Car Assembly Plant
               - They are faster and more accurate in their work e.g. Circuit Assembly
               - They can reduce the risk to human lifes e.g. Bomb Disposal

Weaknesses - Cannot cope with uncertainty or unpredictability
                    - Cannot make decisions or social decisions
                    - Still need a human commander
                    - Can only do the job they have been programmed to do
                    - They can act but cannot think

Consequences Of Using Computers

Legal

The Computer Misuse Act (1990)
- There to protect against unauthorised use of computer systems
- Three Levels - 1. Unauthorised access to data and programs
                       - 2. Unauthorised access and committing further offenses
                       - 3. Unauthorised modification of computer material
- Unauthorised access can be known as cracking or hacking
- Maximum penalty is a fine or a prison sentence

Data Protection Act - Commissioned in 1984 and recommissioned in 1998
- 8 Principles - Data Gathering - Subject knows that data is being gathered
                     - Data Purpose - Obtained for one or more specific purposes
                     - Data Quantity - How much data is recorded
                     - Data Quality - Data should be accurate and up to date
                     - Data Lifetime - Data kept for a certain amount of time
                     - Subject's Rights - Only processed under consent of subject
                     - Internal Data Security - Appropriate technical measures to keep data safe
                     - External Data Security - Is it being moved between countries

Regulation of Investigatory Powers Act (2000) - Referred generally as RIPA
- Prevents the interception of public or private messages
- Security can intercept as long as they have a warrant
- Can be used to force ISPs to help them (Encryption Keys)
- Only applies when the message is being delivered
- In a mailbox it is then covered by the Data Protection Act

Copyright, Designs and Patents Act (1988)
- Protects materials - Music, Art and Films
                              - Only use copyright items with owners consent
                              - Design right protects how something looks
                              - Patents protect how an innovation works and what it does
                              - Trademarks protect the name or logo used by a business

Health and Safety Regulations (1992)
- Employers must look after staff who use computers for a long time
- Software designers must think about colour schemes and font types
- Designers should try to reduce the amount of typing and mouse clicks


Ethical and Social
Digital Rights Management (DRM)
- Application of controls which limit the use of digital media
- Used by copyright owners to limit when you can use digital media
- It can limit the number of plays, number of transfers etc.
- Proprietary Software - Comes with a license
                                   - Must not be changed, re-sold or passed on
                                   - Open Source - Free software with different controls
                                   - Can be modified, re-used
                                   - Cannot be sold thought to make money


Code Of Conduct
- A set of instruction for how you should behave at a computer.
- Not a law - but each company has disiplinary actions
- May cover items such as - Not using other people's accounts
                                         - Not interfering with other people's work
                                         - Not to download software or install software
                                         - Not looking at personal information - e-mail, socialising
                                         - Not to use them for copying material

Sunday 5 December 2010

Fetch, Execute Cycle & Registers Used

- Instructions are fetched from the main memory
- Intructions are then decoded
- Instructions are then executed

Registers
Program Counter (PC) - Holds the address of the next instruction to be executed
Current Information Register (CIR) - Holds the current instruction while it's decoded and executed
Memory Address Register (MAR) - Holds the address of the memory location being accessed
Memory Buffer Register (MBR) - Holds data being transferred to or from the memory that is held in the MAR
Accumulator (ACC) - Holds the result of the current calculations

Basic Machine Code Operations

- High Level language programs are translated into Machine Code
- The processor decodes this Machine Code to run programs
- Machine Code - Operation Code (what to do)
                          - Operand (what to do with it)

What do I need to know?
- Load 15 (meaning load whatever is in memory location 15)
- Store 6 (meaning store whatever number is in the accumulator into memory location 6)
- Add #10 (meaning add the number 5 to the accumulator)

# is important to signify a number

Factors Affecting Processor Speeds

Clock Speed - The clock executes a set of instructions by ticking.
                     - Each instruction takes one or more ticks.
                     - The faster the clock the faster a program can be executed.
                     - Double the clock speed and you would double the performance.

Bus Width - The number of wires within a bus (8, 16, 32, 64)
                 - Each wire has a high voltage or a low voltage (1 or 0)
                 - The larger the number of wires the larger number of instruction can be passed through
                 - The bigger the bus, the less data has to be broken into smaller pieces, therefore increasing performance.

Word Length - The number of bits in a binary number that can be sent
                     - The largest number sent has to be equal to the number of wires on the Bus
                     - Common word length is 32 or 64 bits
                     - The bigger the word length, the less data has to be broken into smaller pieces, therefore increasing performance.

Multicore Processors - Adding more than one processor allows the computer to do things at the same time
                                 - Dual Core is now standard in computers
                                 - Quad Core is becoming common in computers

Three Box Model

The Three Box model has three components to it - Processor
                                                                          - Main Memory
                                                                          - Inputs & Outputs (I/O)

It also has a Bus which combines these components.

Processor - The brain of the system.
                - Responsible for executing programs
                - Contains a microprocessor, which can contain up to 1 billion transistors

Main Memory - Also known as the Immediate Access Memory
                      - Used to store program instructions and data
                      - Random Access Memory - Loses its data when Computer is turned off
                      - Read Only Memory - Keeps it's data (non-volatile)
                      - ROM is used to store programs which boot the computer.

Inputs & Outputs (I/O) - Everything outside the computer is a peripheral.
                                    - I/O controllers allows the CPU to communicate with them

Bus - Can be called System Bus or External Bus
       - Connects the Three Boxes together
       - Three Types - Data - Bidirectional (Two Way)
                                         - Consists of 32 wires
                                         - Used to transport Data
                              - Address - One Directional
                                              - Consists 32 wires
                                              - Used to address Memory and I/O locations
                              - Control - Bidirectional (Two Way)
                                             - Consists of 8 wires
                                             - Used to transport control signals between the three components