EMBEDDED SYSTEMS

Definition:

• Embedded systems are computers that are built into other devices.
• They are systems dedicated to a specific job.
• They are often used as control systems.

Example Uses:

• Dishwashers.
• Microwaves

Advantages:

• Dedicated to a single task so are easier to design.
• Cheaper to produce as they consist of less parts.
• Efficient because they only have one job to do.

THE CPU

Definition:

• The Central processing unit.
• The CPU is the "Brain" of a computer, it process all of the data and instructions that make the system work.

The parts of the CPU:

The Control Unit (CU):

• The control unit ultimatley controls the entirety of the CPU as its main job is to execute program instructions by following the Fetch Decode Execute Cycle.
• It controls the flow of data inside the CPU and outside the CPU.

The Arithmetic Logic Unit (ALU):

• Ultimatley does all of the calculations and comparisions.
• It also completes logic operations and binary shifts.
• Registers store the results made by the ALU.

The Cache:

• Cache is very fast memory in CPU, however, slower than registers but faster than RAM.
• Cache hs a very low capacity but is also very expensive compared to RAM and secondary storage.
• Cache stores regularly used data for the CPU to access quickly because when it needs data, it checks Cache first then RAM.

The Clock:

• The clock sends out signals at a constant rate that cycle between 1 and 0.
• The signal is used to synchronise the rate at which instructions are carried out.
• The rate of the clock cycles is called the clock speed.

The Buses:

• Buses are collections of wires used to transmit data between components of the CPU and other parts of a computer.

The Registers:

• Registers temporarily hold tiny bits of data needed by the CPU.
• They are very quick at reading and writing, more than any other type of memory.

CPU PERFORMANCE

Clock Speed:

• The CPU is regulated with clock signals so a set number of instructions are executed per clock cycle.
• The faster these cycles are, the more instructions can be executed per second.
• increasing Clock Spped = Increased Performance

CPU Cores:

• Multiple cores means multiple instructions can be executed simultaneously.
• Increasing Number of Cores = Increased Performance

Cache Size:

• Cache stores regularly used data that may be used by the CPU so it can be accessed quickly.
• So the larger the cache size, the more instructions can be accessed faster so the fetch stage is quicker.
• Increasing Cache size = Increased Performance