Factors Affecting CPU Performance and Embedded Systems

Clock speed

The speed at which a processor operates, measured in hertz (Hz), indicating the number of cycles per second.

Hertz

The unit of frequency that measures the number of cycles per second.

Gigahertz (GHz)

A unit of frequency equal to one billion hertz, used to measure clock speed.

Typical clock speeds for a PC

Between 2GHz and 4GHz.

Cache memory

A small amount of much faster memory used to temporarily store frequently used instructions or data, acting as an intermediary between main memory and the CPU.

Random Access Memory (RAM)

Main memory used for reading from and writing to, which is slower than the speed at which the processor can work.

Cache size

The amount of cache memory available in a computer, which affects how much data and instructions can be held for quick access.

Number of cores

The number of processing units within a CPU that can execute instructions independently.

Bottleneck

A limitation in a system that slows down overall performance, such as a slow component in a computer.

Compromise between speed and cost

The balance that must be struck when choosing memory technologies, where faster memory increases cost.

Typical RAM size in 2020

A typical PC might have 8 or 16GB of RAM.

Typical cache memory size

A typical PC might have 2MB of cache memory.

Data access speed

The speed at which data can be read from or written to memory, which affects CPU performance.

Processor performance

The efficiency and speed at which a CPU can execute instructions, influenced by clock speed, cache size, and number of cores.

Memory technologies

Different types of memory used in computers, which can vary in speed and cost.

Accessing main memory

The process of retrieving or storing data in RAM, which is slower than accessing cache memory.

Improving CPU performance

Can be achieved by increasing cache memory, allowing more data and instructions to be held for quick access.

Electrical current changes

The rate at which the electrical signals in the processor circuits change, which is measured in hertz.

Three-lane motorway analogy

An analogy used to explain how a bottleneck can limit overall speed, similar to traffic flow being limited by a single-lane road.

Fetch, decode, and execute

The three primary stages of instruction processing that occur on the clock cycle of a CPU.

Units of measurement

There are 1000 megabytes in a gigabyte, highlighting the difference in scale between cache memory and RAM.

Level 1 cache

Extremely fast but small cache memory, typically between 2-64KB, that speeds up the Fetch-Execute cycle.

Level 2 cache

Fairly fast cache memory, much faster than RAM, with a medium size of 256KB-2MB.

Level 3 data cache

An additional cache level present in some CPUs.

Clock speed

The speed at which a CPU can execute instructions, affecting overall computer performance.

Cache memory

A type of fast memory that stores frequently accessed data to speed up processing.

Dual-core processor

A CPU with two processing units, allowing for parallel processing of instructions.

Quad-core processor

A CPU with four processing units, enabling simultaneous execution of multiple instructions.

Parallel processing

The ability to execute multiple instructions at the same time, facilitated by multi-core processors.

Embedded system

A small computer built into a piece of equipment designed to perform a specific function.

Characteristics of an embedded system

Reliability and minimal resources such as ROM, timers, sensors, and actuators.

ROM in embedded systems

The memory where the controlling program is held, which cannot be changed.

Machine-efficient language

A programming language designed to use minimal memory and execute quickly, often used in embedded systems.

Assembly language

A low-level programming language used for critical parts of embedded system programs.

Embedded operating system

A simple operating system that does not need to be loaded at startup, as it is stored in ROM.

Single application

The capability of an embedded operating system to run only one application at a time.

User interface in embedded systems

Typically very simple, such as buttons on a microwave or washing machine, and may be absent in some systems.

Sensors in embedded systems

Devices designed to measure external stimuli and react accordingly, such as in a central heating system.

Fetch-Decode-Execute cycle

The basic operational process of a CPU where it fetches, decodes, and executes instructions.

Multi-core processor

A CPU that contains multiple cores, allowing for faster operation by executing many tasks simultaneously.

Performance of a computer

The speed and efficiency with which a computer can execute tasks, influenced by factors like clock speed and cache memory.

Expensive memory type

The type of memory that costs the most to manufacture and implement in computing systems.