Computing Hardware - CPU and Memory

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OCR Computing - Hardware

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Created by ollietablet123 about 4 years ago
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Computing Hardware - CPU and Memory
1 Processing
1.1 Computers require an input hardware, processing hardware and output hardware.
1.2 CPU
1.2.1 executes programs using the fetch-decode-execute cycle
1.2.2 Memory
1.2.2.1 Stores program operations and data while the program is being executed. Types: Registers, cache, RAM, ROM and Virtual Memory
1.2.3 Storage
1.2.3.1 Stores programs and files long term, even when not in use. Types include: USB, SD Cards, Hard-Drives and SSDs
1.3 Graphics
1.3.1 Most computers have a separate GPU and CPU
1.3.2 Using the GPU to render images, frees up the CPU for other tasks
1.4 Performance
1.4.1 Benchmarking
1.4.1.1 A test used to access the performance of a computer. Different types of software are used depending on the computers purpose.
1.4.2 CPU speed (cycles per second) measured in Hertz
1.4.2.1 GHz
1.4.2.2 MHz
1.4.2.3 KHz
1.4.2.4 Hz
2 CPU and Memory
2.1 Factors that affect performance
2.1.1 Cores
2.1.1.1 CPU can contain one or more processing units (cores). A core contains a ALU, Control Unit and Registers.
2.1.1.2 Cores communicate through channels therefore doubling cores does not double speed
2.1.2 Clock Speed
2.1.2.1 The clock speed - also known as clock rate - indicates how fast the CPU can run. This is measured in megahertz (mHz) or gigahertz (gHz) and corresponds with how many instruction cycles the CPU can deal with in a second.
2.1.3 Cache Size
2.1.3.1 Cache is a small amount of memory which is a part of the CPU - closer to the CPU than RAM. It is used to temporarily hold instructions and data that the CPU is likely to reuse.
2.1.3.2 The CPU control unit checks the cache for instructions before the RAM.
2.1.3.3 Larger the Cache = the more data can be stored closer to the CPU
2.1.3.3.1 L! - part of the CPU chip, smallest and fastest to access (between 8KB and 64KB
2.1.3.3.2 L2/3 - larger, extra cache built between the CPU and RAM. More L2/3 = faster a computer can run
2.1.4 Processor Type
2.1.4.1 CISC
2.1.4.1.1 Complex Instruction Set Computing
2.1.4.1.2 Used by most laptops/desktops - made by Intel/AMD
2.1.4.2 RISC
2.1.4.2.1 Reduced Instruction Set Computing
2.1.4.2.2 Used in tablets/smartphones
2.1.4.3 Differences
2.1.4.3.1 RISC have less instructions. RISC more efficient at simpler tasks
2.1.4.3.2 Physical Size - CISC are larger and require more silicon
2.1.4.3.3 Speed - RISC run at a lower clock speed
2.1.4.3.4 Energy Consumption - CISC are larger and therefore use more energy
2.1.4.3.5 Design - RISC combines architecture onto one chip (SOC), whereas CISC are built seperatly a system with heat sinks and fans - RISC do not.
2.1.4.3.6 Cost - RISC use less power and are cheaper to make
3 Bridges
3.1 Bridges manage how data and instructions are transferred between devices
4 Memory
4.1 Memory is the area where the computer stores or remembers data. Memory provides the CPU with its instructions. AKA Primary Storage
4.1.1 Closer to CPU = quicker the CPU can access instructions
4.2 VOLATILE
4.2.1 Only stores information to run programs while the PC is on. Reset when the PC is turned off. Requires electricity to store data using transistors and capacitors
4.3 NON-VOLITILE
4.3.1 Retains data even when the computer is off. Examples in old computers: paper, punched tape and floppy disks
4.4 Latency is the time for components to respond to a request