Sec 5. Chap 25 : Internal computer hardware. Flashcards
Processor.
Processor (CPU) is the logic circuitry that responds to the processes of basic instructions that drive a computer. Contains multiple units and registries.
Computer buses.
A bus is a communication system that transfers data between components inside a computer, or between computers.
Control bus.
The control bus is bidirectional and assists the CPU in synchronising control signals to internal devices and external components. It is comprised of interrupt lines, byte enable lines, read/write signals and status lines.
Data Bus.
Data bus provides a connection between components within a computer, to send and receive data.
Data bus’ have a direct impact on computer performance, the volume of the data bus dictates the word size. For instance a bus with only 8 lanes would have to send twice for one instruction that was a word of 16 bits.
Address bus.
When the cpu wishes to access a specific part of main memory, that address is placed on the address bus and the data within that is sent back along the data bus. Because the address bus only sends addresses, it is unidirectional. Address bus’ also determines the maximum amount of space in main memory, addressable locations.
I/O Controller.
The main purpose of this system is to help in the interaction of peripheral devices with the control units (CUs). Put simply, the I/O controller helps in the connection and control of various peripheral devices, which are input and output devices.
Each device has a separate controller which connects to the control bus. I/O controllers receive input and output requests from the processor, and then send device-specific control signals to the device they control. They also manage the data flow to and from the device.
- an interface that allows connection of the controller to the system or I/O bus
- a set of data, command and status registers
- an interface that enables connection of the controller to the cable connecting the device to the computer
Interface.
A standardised form of connection defining such things as signals, number of connecting pins/sockets and voltage levels that appear at the interface. An example is a Universal Serial Bus (USB) connection, which can be used with many different peripherals.
Von Neumann architecture.
Specifies the basic components of the computer and processor in which a shared memory and bus is used for both data and instructions - based on the stored programme concept.
Consists of a Control Unit, Arithmetic and Logic Unit (ALU), Memory Unit, Registers and Inputs/Outputs.
Stored Programme concept.
Machine code instructions are fetched and executed serially by a processor that performs arithmetic and logical operations.
The programme must first be within main memory to be executed and the machine code execution cycle happens one at a time.
Harvard architecture.
The Harvard architecture is a computer architecture with separate storage and signal pathways for instructions and data.
Used mainly for embedded systems, for special operations. Harvard is faster than Neumann because data and instructions can fetched in real time - better for real time systems.
