Program counter // PC
• Stores the address of the next instruction to be fetched
Memory address register // MAR
• Stores the address where data/instruction is to be read from or saved to
Memory data register // MDR
• Stores data that is about to be written to memory // Stores data that has just been read from memory
Current instruction register // CIR
• Stores the instruction that is currently being decoded/executed

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

– if one station/cable fails, others are not affected
– easier to identify faults when using star topologies
– it is easier to expand this type of network
– performance doesn’t deteriorate under load

• All nodes ‘listen’ for traffic to sense when the network is idle.
• When a node wishes to transmit, it transmits a ‘request to send’ frame’ (RTS)
• The intended receiving device will transmit a ‘clear to send’ (CTS) frame if it is available.
• All other nodes ‘sense’ the network is busy and wait a random amount of time before trying to transmit

1. Enable resource sharing
2. Facilitate remote communication
3. Enable distributed processing
4. Provide better data security and management

• Serial is the transmission of data one bit at a time/through one wire
• Parallel is the transmission of data more than one bit at a time/many wires
• Simplex is the transmission of data in one direction only
• Duplex is the transmission of data in both directions simultaneously

• A computer is an electronic device that operates (works) under the control of programs stored in its own memory unit
• An electronic device that accepts data, as input and transforms it under the influence of a set of special instructions called programs, to produce the desired output (referred to as information)

• Registers are small amounts of memory available that hold data fetched from memory or data waiting to be stored in memory. A temporary holding place for the instruction that has been fetched.
• The system clock purpose is to determine the pace of the cycle, each tick of the clock a part of the fetch-execute cycle occurs. Regulates the timing and speed of a computers systems functions.

Physical topology - the physical arrangement of nodes of a computer network

Examples

• bus topology
• ring topology
• mesh topology
• star topology

Logical topology- the way data flows in a network

Examples

• Ethernet
• Ring

• They are small and fit in a small storage space
• They are portable hence can be carried when need to be used outside the office
• Low power consumption
• Have rechargeable batteries

• switches can send and receive data simultaneously - they are full duplex
• a hub is half duplex- only one host can communicate at a time.
• a hub broadcast signals to all computers connected in a network while a switch directs data to its intended destination

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.

Modulation refers to the process of converting a digital signal to analog signal at the transmission end while demodulation is to converting analog signal to digital signal at the receiving end

logging on

•  dial-up/communications software/ISPsoftware

finding websites

•  browser/search engine

• Hierarchical model  - Records in the database can be related to one parent only but can have more children records
• Network database model - a child record can be linked to  multiple parent records
• Relational database model - organizes data into tables that can be linked or related based on data common to each.

• 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

i) To manage the execution of instructions
By running a clock
To decode instructions
(ii) To store OS
To store those parts of applications programs currently running
To store data currently in use
(iii) Part of the processor where data is processed/manipulated
All I/O must pass through here

Both translate source code written in high level programming languages into machine code.
Compiler: Produces a single executable file that is portable between machines
Interpreter: Source code needs a special environment to run
Compiler: Needs to be compiled for a particular architecture
Interpreter: Can run on any architecture that has the translator/interpreter
Complier: Entire source code file is translated at once
Interpreter: Code is translated line by line
Compiler: Provides error report at the end of the compilation
Interpreter: Errors more obvious in the sequence
Compiler: The program source code is not available (so helps protect IP)
Interpreter: Source code is available
Compiler: Only has to be translated once (affecting the speed of execution)
Interpreter: Has to be translated each time, therefore (affecting the speed of execution)
Compiler: Requires two files to be maintained (one for execution and for editing purposes)
Interpreter: Requires only one file to be maintained
 

• In a client-server network, every device is either a client or a server whereas in a peer-to-peer network each computer has equal responsibility and each has the ability to work as both a server and a client