1.1 system architecture

1.1 system architecture

1. processor

   • Computers require input hardware, processing hardware and output hardware. The hardware that defines a computer is the CPU and memory. Without these a computer could not function.
   • CPU - executes programs using the fetch-decode-execute cycle
   • Memory - stores program operations and data while a program is being executed. There are several types of memory, including: registers, cache, RAM and virtual memory.
   • Storage - stores programs and files long term, even when they are not in use. Devices such as hard drives, USB memory sticks or SD cards are used to store files such as photos, music and software applications long term

2. Cores

   • A CPU can contain one or more processing units. Each unit is called a core. A core contains an ALU, control unit and registers. It is common for computers to have two (dual), four (quad) or even more cores. CPUs with multiple cores have more power to run multiple programs at the same time.
   • However, doubling the number of cores will not simply double a computer's speed. CPU cores have to communicate with each other through channels and this uses up some of the extra speed

3. Clock Speed

   • 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. A 2 gHz CPU performs two billion cycles a second. A faster CPU uses more energy and creates more heat.
   • A computer will normally have a maximum clock speed set by default, but it is possible to change this speed in the computer BIOS. Some people increase a CPU clock speed to try to make their computer run faster - this is called overclocking.
   • There are limits to how fast a CPU can run and its circuitry cannot always keep up with an overclocked speed. If the clock tells the CPU to execute instructions too quickly, the processing will not be completed before the next instruction is carried out. If the CPU cannot keep up with the pace of the clock, the data is corrupted. CPUs can also overheat if they are forced to work faster than they were designed to work.

4. Mother Board

   • The motherboard is a circuit board that connects the CPU to the memory and all the other hardware. The CPU sits on the motherboard (also called the logic board).
   • Buses are circuits on the motherboard that connect the CPU to other components. There are many buses on the motherboard. A bus moves instructions and data around the system. The speed of a bus is measured in megahertz (MHz). The faster the bus, the faster data is communicated. The speed of the motherboard is defined by the bus speed.
   • Buses are limited by their width in bits. They are usually 8, 16 or 32-bits wide. This tells us how many bits can be sent by the bus at any one time, eg a 32-bit bus can send 32 bits at once.
   • Address bus - this sends information about where data needs to go by sending an address to the memory. The address bus only sends data in one direction - from the CPU to RAM. Data bus - this sends data to the memory or receives data from the memory. Data can flow both ways along the data bus

5. bridges

6. embedded systems

   • An embedded system is a small processor (computer) that is inside a large piece of equipment, e.g. washing machine. This has a processor and memory chips and of course all the pre-set washing machine programs for the washing. It also has a specific dedicated function

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