Computer Science
- Created by: AOconnor
- Created on: 13-05-18 15:40
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- Computer Science
- Von Neumann Architecture
- Both the computer program and the data it processes are stored in memory
- MAR
- Location address in memory of next instruction/data CPU needs to fetch/store
- MDR
- Temporarily stores instructions/data fetched from memory until needed
- PC
- Provides CPU with memory address of next instruction in cycle to be executed
- Accumulator
- Temporarily stores results of calculations until needed
- Bus
- Physical pathway shared by signals to and from components of system
- Arrows represent wires and circuit boards
- Physical pathway shared by signals to and from components of system
- CPU
- Processes information/instruction and coordinates flow of data around system
- Cache
- Small and extremely fast memory that stores data while instructions are carried out
- Prevents data bottlenecks when communicating with RAM and secondary storage
- Small and extremely fast memory that stores data while instructions are carried out
- CU
- Controls flow of data around system
- ALU
- Performs mathematical and logic calculations
- FDE cycle
- Instruction fetched from memory
- instruction decoded
- Decoded instruction executed so CPU performs contiuously
- Process repeated
- Program counter incremented
- Process repeated
- Decoded instruction executed so CPU performs contiuously
- instruction decoded
- Instruction fetched from memory
- System Security
- Firewall
- Prevents unauthorised access
- Anti-malware
- Removes viruses from infecting system
- Encryption
- Renders intercepted data useless
- User-access levels
- Users have restricted access
- Network Policies
- Rules that define acceptable use
- Firewall
- Secondary storage
- Magnetic
- Advantages
- High capacity, low cost
- Fast data access
- Disadvantages
- Disk eventually fails
- Easily damaged (corruption of data)
- Large physical size
- Moving parts
- Uses
- Network storage
- Desktop PCs
- Large documents
- Backup systems
- Advantages
- Optical
- Advantages
- Cheap
- Portable
- Widely available
- Disadvantages
- Discs damage easily and degrade over time
- Limited capacity
- Compatibility issues
- Uses
- Storing music/videos
- CD/DVD/Blu-ray
- Advantages
- Solid State
- Advantages
- Fast access
- Small physical size
- No moving parts
- Very portable
- Disadvantages
- Most expensive
- Wears out over time
- Uses
- USB portable drives
- Smartphone and camera memory
- Laptop hard drives
- Advantages
- Magnetic
- Von Neumann Architecture
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