The hardware are the parts of computer itself including the Central Processing Unit (CPU) and related microchips and micro-circuitry, keyboards , monitors , case and drives (floppy, hard, CD, DVD, optical, tape, etc...). Other extra parts called peripheral components or devices include mouse, printers, modems, scanners, digital cameras and cards (sound, video) etc...
Together they are often referred to as a personal computers or PC s.
Role chart of per-device Monitor Speaker Image Scanner Printer Key Bord Mouse PC(Body) CD-ROM Drive FD Drive
Internal structural chart of main body Power supply Case CD-ROM Drive Front cover FD Drive HD Drive Main Board 5 Inch drive bay 3.5 Inch drive bay Expansion card slot
Component in main body of internal structural chart of main body Power supply Main Board CD-ROM HDD FDD Connected cable Graphics Card Memory CPU Cooling Wheel
Main Board Power supply connector FD drive connector IDE connector (HDD,CD-ROM) BIOS ROM Backup battery PCI Slot AGP Slot Expansion card slot PS/2 Port (Key board, Mouse) Chip Set Printer Port Serial port Sound port LAN port USB port CPU Slot
In computing, input/output , or I/O , is the collection of interfaces that different functional units (sub-systems) of an information processing system use to communicate with each other, or the signals (information) sent through those interfaces.
Inputs are the signals received by the unit, and outputs are the signals sent from it. The term can also be used as part of an action; to "do I/O" is to perform an input or output operation.
I/O devices are used by a person (or other system) to communicate with a computer. For instance, keyboards and mouses are considered input devices of a computer and monitors and printers are considered output devices of a computer.
Typical devices for communication between computers are for both input and output, such as modems and network cards .
Primary storage is directly connected to the central processing unit of the computer. It must be present for the CPU to function correctly , just as in a biological analogy the lungs must be present (for oxygen storage) for the heart to function (to pump and oxygenate the blood). As shown in the diagram, primary storage typically consists of three kinds of storage:
Secondary and off-line storage Secondary storage requires the computer to use its input/output channels to access the information , and is used for long-term storage of persistent information. However most computer operating systems also use secondary storage devices as virtual memory - to artificially increase the apparent amount of main memory in the computer. Secondary storage is also known as " mass storage ", as shown in the diagram above. Secondary or mass storage is typically of much greater capacity than primary storage (main memory), but it is also much slower. In modern computers, hard disks are usually used for mass storage.
The time taken to access a given byte of information stored on a hard disk is typically a few thousandths of a second, or milliseconds. By contrast, the time taken to access a given byte of information stored in random access memory is measured in thousand-millionths of a second, or nanoseconds. This illustrates the very significant speed difference which distinguishes solid-state memory from rotating magnetic storage devices: hard disks are typically about a million times slower than memory. Rotating optical storage devices (such as CD and DVD drives) are typically even slower than hard disks, although their access speeds are likely to improve with advances in technology.
A control unit is the part of a CPU or other device that directs its operation. The outputs of the unit control the activity of the rest of the device. A control unit can be thought of as a finite state machine.
At one time control units for CPUs were ad-hoc logic, and they were difficult to design. Now they are often implemented as a microprogram that is stored in a control store. Words of the microprogram are selected by a microsequencer and the bits from those words directly control the different parts of the device, including the registers, arithmetic and logic units, instruction registers, buses, and off-chip input/output. In modern computers, each of these subsystems may have its own subsidiary controller, with the control unit acting as a supervisor. (See also CPU design and computer architecture.)
The arithmetic logic unit (ALU) is a digital circuit that calculates an arithmetic operation (like an addition, subtraction, etc.) and logic operations (like an Exclusive Or) between two numbers. the ALU is a fundamental building block of the central processing unit of a computer.
Many types of electronic circuits need to perform some type of arithmetic operation, so even the circuit inside a digital watch will have a tiny ALU that keeps adding 1 to the current time, and keeps checking if it should beep the timer, etc...
Motherboard or system board with slots for expansion cards and holding parts ** Central processing unit ( CPU )
Computer fan - used to cool down the CPU
Random Access Memory ( RAM) - for program execution and short term data storage, so the computer does not have to take the time to access the hard drive to find the file(s) it requires. More RAM will normally contribute to a faster PC. RAM is almost always removable as it sits in slots in the motherboard, attached with small clips. The RAM slots are normally located next to the CPU socket.
Basic Input-Output System (BIOS) or Extensible Firmware Interface (EFI) in some newer computers
Power supply - a case that holds a transformer, voltage control, and (usually) a cooling fan
Storage controllers of IDE, SATA, SCSI or other type, that control hard disk, floppy disk, CD-ROM and other drives; the controllers sit directly on the motherboard (on-board) or on expansion cards
Video display controller that produces the output for the computer display. This will either be built into the motherboard or attached in its own separate slot (PCI, PCI-E or AGP), requiring a Graphics Card .
Computer bus controllers ( parallel, serial, USB, FireWire ) to connect the computer to external peripheral devices such as printers or scanners
Internal storage - keeps data inside the computer for later use.
Structure of CD-ROM 12cm in diameter 1.2mm in thickness Polycarbonate base Recording layer (reflection film) Protection film (about 10 um)
Structure of DVD-ROM Structure to paste with adhesive and to put two of 12cm in diameter and 0.6mm in thickness disks together Polycarbonate base The above recording layer (translucent reflection film) Transparent film (about 10μm) Recording layer in the under (reflection film) Protection film (about 10μm)
Arrangement chart of Strage CD-ROM Drive DVD-ROM Drive Etc. Drive in enhancing bay FD Drive Internal HD Drive SCSI interface Interface cable External Drive Unit