• when designing a database a data dictionary provides the description and purpose of the fields/attributes of the database table(s). For example the field name (i.e. “phone number”), the data type (text); the size of the field (10) etc.

Input : An algorithm can take 0 or more inputs well defined outputs

Finiteness: an algorithm must terminate in finite time and after finite number of steps. 

Definiteness : an algorithm must be clear and unambiguous. Each and every step of an algorithm must be clear and precise and it must have only one meaning

Feasibility: should be feasible with the available resources

Output : must produce at least one well defined output

Independent : should have a step-by-step directions which is independent of any programming language

Correctness: should solve the problem it is designed to solve

Efficiency: must take the shortest time possible to run and should require the least memory space. It should use a minimum number of computation steps and memory to produce the desired  output. takes little time and memory to run

Generality: should not be limited to a specific case. It should work for all the valid inputs. works for many possible inputs

Effectiveness : should statements that are relevant to the problem. Every step must be basic and essential. 

• Authenticity
• Users' needs
• Availability of documentation
• Cost
• Compatibility
• Upgradability
• Portability

• it is a format style that shows the listed items of different levels rather than at one level. Each level has a different indentation and numbering style

1. Chapter 1

     1.1. Introduction

                 1.1.1.Definition of terms

        Misreading error

• Easy to add nodes
• Managed centrally
• Fewer data collisions
• A single node failure does not affect the rest of the network

• Refers to the delivery of multimedia content, such video or audio over the internet in real-time. It allows users to access and consume content without downloading it to their device beforehand.

• car factories/factories
• chemical/nuclear factories
• production lines
• warehouses
• deep in the ocean/down mines
• on other planets/in space
• road junctions

Acme company needs to ensure that if they are reselling the drives they wipe the drive (this should be done regardless of the destruction of the drive) to the DoD standard.

• Disassemble the drive by pulling it apart the drive so that the data would not be accessed
• Destroy the metal disk either by drilling holes so it cannot be read
•  Encrypt drives with passwords that are not accessible
• Degaussing the hard drives
• Use specialized overwriting software

This would ensure that any software cannot be used to locate files.

• Simple technology is needed to develop both hardware and software.
• Digital devices are more reliable, small in size and use less power as compared to analog devices.
• Devices that read, process or output data in digital form are used in computers and other digital devices such as calculators.

Direct changeover – new system replaces existing system immediately/overnight

 Parallel running – new system runs alongside/together with existing system

Parallel running – there is always the old system to fall back on in the event of the new system failing/information is not lost/always a second copy

Direct changeover – if things go wrong lose all data/old system is not available

Direct changeover – training is more difficult to organise

Parallel running – training can be gradual Parallel running is more expensive to implement than direct changeover....

Direct changeover is a quicker method of implementation than parallel running

Direct Changeover: The old system is stopped completely, and the new system is started. All of the data that used to be input into the old system, now goes into the new one.

 Parallel Running: The new system is started, but the old system is kept running in parallel (side-by-side) for a while. All of the data that is input into the old system, is also input into the new one. Eventually, the old system will be stopped, but only when the new system has been proven to work.

• where the new system is completely different from the old one
• if there has been extensive testing of the system and the system analyst has confidence in its functionality
• If the system is not critical

Open source : refers to software provided freely with its source code. The user can modify and redistribute the software.

Freeware: these are software that can be downloaded for free and distributed, buta  the source code is hidden and cannot be altered.

Shareware: is software that is available for free within a given trial period, after which it must be bought.

Proprietary: software made for commercial purposes. The source code is hidden, and it can only be used after paying for a licence.

Data and instructions are fetched from main memory, from addresses requested by the CPU on the address bus. (Data and instructions are sent) using the data bus. (Data and instructions are then) decoded and executed in the CPU.
Results of operations are sent back to the memory on the data bus

• a repeater is a two-port device that amplifies a signal from one port to another
• a switch is a multiport device that uses a table of addresses to send a signal through the correct port

(a) byte

• fixed number of bits, 8 bits
• represents a character

(b) compiler  program

• converts/changes/translates high-level language into machine code/machine language/low-level language/object code
• changes each high-level language instruction into machine code instructions
• produces an independent program capable of being executed by itself
• all (syntax errors) listed
• converts the whole program before execution/in one go
• converts source code to object code

(c) handshaking

• exchanging of signals to establish communication between two devices/computers e.g. printer and computer, modem and computer

(d) technical documentation

• documentation to ensure that the system can be maintained/updated/altered/developed/upgraded
• trouble shooting/correcting errors/correcting faults
• explanation of what the program does/how the system works
• contains file structures
• algorithms/flow charts/pseudo code
• program listings
• hierarchical chart

(e) simulation

• studying the behavior of a system by using a model/represents real-life/mathematical representation
  e.g. flight simulator (or others), hazardous applications results can be predicted

• RAID 10 is a combination of RAID 0 (zero) and RAID 1 (one)

Incremental:

• Only the changes need to be backed up
• The software/OS/settings are unlikely to have changed between backups
• Small number of files likely to be used/edited between backups
• Take less time to backup
• Each backup will take less memory space to store

Full:

• Backup all the data/files and software
• It might not take a significant time to back up entire system
• He might only have a small number of files to be backed up each time
• Safer as have more past versions to revert to
• User may have changed settings on computer
• Faster to restore the backup
• Needs to do a full before he can do an incremental

1. Hardware failure
2. Corrupted software files
3. Hacking into the system
4. Power failure

• virtual memory