The Physical Parts of a Computer System
Computer systems generally fall into one of four categories:
- Obsolete (or, "Legacy")
- Low performance
Which of these categories a computer comes under depends on the quality, value and performance of its components. The components often have long names that are shortened to
acronyms (see below). While it is not necessary to know the hundreds and hundreds of acronyms used to describe the particulars of computer science, it is helpful to know the main
ones as they apply to the more common hardware components of a computer system.
- CPU stands for "Central Processing Unit"
- The CPU is the "brain" of the computer: the circuitry that carries out the instructions of a computer program by performing specific
- It works with 1s and 0s (bytes)
- Traditionally, the term CPU refers to a processor, though nowadays it can also include "microcontrollers" or Systems on a Chip (SoC)
- The motherboard is the "highway" of the computer
- Its job is to connect all the components and parts
- It also provides connections for other peripherals
- PSU stands for "Power Supply Unit," often just called "power supply"
- It converts power from AC to DC
- It has connections for various components on the motherboard
- All power supplies have a power input and a power output
- RAM stands for "Random Access Memory"
- It is a form of computer data storage
- Different types of RAM fit different motherboards
- RAM is the most common type of memory... but it is not the only kind
(N.b. The difference between volatile and non-volatile memory is as follows: non-volatile memory is memory that does not require a connection to a power source to retain
information, whereas volatile memory does)
- ROM stands for "Read-Only Memory"
- It stands for memory that can only be modified slowly, with difficulty, or not at all
- "More recently, ROM has come to include memory that is read-only in normal operation, but can still be reprogrammed in some way." (Wikipedia)
- PROM ("programmable ROM") is memory on a data chip that can be written only once
- It is usually used to store low-level programs such as firmware
- "Firmware is software that is embedded in a piece of hardware." (Lifewire.com)
- In other terms, firmware is "a microprogram stored in ROM, designed to implement a function that had previously been provided in software." (Dictionary.com)
- EPROM ("erasable programmable read-only memory") can be written, erased, and then written again by ultraviolet light
- It retains its data when the power is switched off
- Examples of EEPROM ("electric erasable programmable read-only memory") are flash drives and SSDs (solid-state drives)
- EEPROM is "used to store relatively small amounts of data but allowing individual bytes to be erased and reprogrammed." (Wikipedia)
- A CPU cache is a hardware cache used by the CPU to reduce the time to access data from the main memory
- "A cache is a small amount of memory which operates more quickly than main memory. Data is moved from the main memory to the cache, so that it can be accessed faster." (Wikibooks.org)
- Note on split caches: "Almost all current CPUs with caches have a split L1 cache. They also have L2 caches, and, for larger processors, L3 caches as well. The L2 cache is usually not split and
is usually shared between caches." (Wikipedia)
Figure 20: Diagram of split L1 cache/shared L2 cache
- Stands for "Peripheral Component Interconnect"
- PCI is "an interconnection system between a microprocessor and attached devices in which expansion slots are spaced closely for high speed operation." (Techtarget.com)
- "PCI transmits 32 bits at a time in a 124-pin connection... and 64 bits in a 188-pin connection in an expanded implementation."
- Stands for "PCI express"
- "A high-speed serial computer expansion bus standard, designed to replace the older PCI, PCI-X, and AGP bus standards." (Wikipedia)
- It has "numerous improvements over the older standards."
- The slots go from x1 to x16, depending on how many "lanes" the slot has
- "Short for Accelerated Graphics Port, AGP is an advanced port designed for video cards and 3D accelerators. Designed by Intel and introduced in August of 1997, AGP introduces
a dedicated point-to-point channel that allows the graphics controller direct access to the system memory." (Computerhope.com)
- DIMM is short for "Dual Inline Memory Module"
- DIMM "is a double SIMM (single inline memory module). Like a SIMM, it's a module containing one or several random access memory (RAM) chips on a small circuit board with pins that
connect it to the computer motherboard." (Proprofs.com)
- They are commonly used today and support 64-bit transfer
- "Compact Disc (CD) is a digital optical disc data storage format, co-developed by Philips and Sony." (Wikipedia)
- The format was originally developed to store and play only sound recordings but was later adapted for storage of data (CD-ROM)
- A CD holds 700MB of data
- DVD stands for "Digital Versatile Disc"
- It is a "digital optical disc storage format invented and co-developed by Philips, Sony, Toshiba and Panasonic in 1995." (Wikipedia)
- Used for a) software and other computer files, and b) video programs watched with DVD players
- It has the same dimensions as a CD but higher storage capacity (it holds 4.7GB of data)
- Short for Blu-Ray Disc, BD or BD-ROM, it is "an optical disc format developed by thirteen consumer electronics and PC companies" (Computerhope.com)
- Blu-Ray can store up to 25GB on a single-layer disc or 50GB on a dual-layer disc, each disc being the same size as a standard CD
- Stands for "Solid-State Drive"
- It is "a storage device containing non-volatile flash memory, used in place of a hard disk because of its much greater speed." (Google)
- "A high-performance plug-and-play storage device that contains no moving parts." (Webopedia.com)
- The data on an SSD is stored on circuits, unlike on an HDD (Hard Disk Drive) on which the data is stored on a magnetic platter
- Stands for "Hard Disk Drive" (sometimes abbreviated as Hard Drive or HD)
- It is "a non-volatile memory hardware device that permanently stores and retrieves information." (Computerhope.com)
- There are many variations, but their sizes are generally 3.5" and 2.5" for desktop and laptop computers respectively
- A hard drive consists of one or more platters to which data is written using a magnetic head, all inside of an air-sealed casing
CPU Socket Types
- LGA and PGA are opposite socket types in their design
- LGA stands for "Land Grid Array" - this has the pins on the motherboard
- PGA stands for "Pin Grid Array" - this has the pins on the CPU
- LGA is newer than PGA and offers the advantages of being easier to put into place without damaging the pins
- CMOS stands for "Complementary Metal-Oxide Semiconductor"
- It is traditionally called CMOS RAM because it uses a volatile, low-power SRAM powered by a small CMOS battery when system and standby power is off
- "Non-volatile BIOS memory refers to a small memory on PC motherboards that is used to store BIOS settings." (Wikipedia)
- This ensures that the BIOS doesn't lose all its data when the computer is powered off
- Stands for "Liquid Crystal Display"
- It is "a digital display that uses liquid crystal cells that change reflectively in an applied electric field." (Thefreedictionary.com)
- It "uses the light-modulating properties of liquid crystals." (Wikipedia)
- Stands for "Serial AT Attachment"
- "[A] computer bus interface that connects host bus adapters to mass storage devices such as hard disk drives, optical drives, and solid-state drives." (Wikipedia)
- "SATA III (revision 3.x) interface, formerly known as SATA 6GB/s, is a third-generation SATA interface, running at 6.0GB/s. The bandwidth throughput, which is supplied by the interface,
is up to 600MB/s." (Kb.sandisk.com)
- USB stands for "Universal Serial Bus"
- It is "an industry standard developed in the mid-1990s that defines the cables, connectors and communications protocols used in a bus for connection, communication, and power supply
between computers and electronic devices." (Wikipedia)
- It was designed in January 1996 and has been produced since May 1996
Types of USB
- 1.0 (low bandwidth/low speed) - 1.5MBits/sec
(full bandwidth/full speed) - 12MBits/sec
- 1.1 - widely adopted and led to Legacy-free PCs
- 2.0 (high speed/high bandwidth) - 480MBits/sec, effective throughput 35MB/sec
- 3.0 (superspeed) - 5.0GBits/sec
- "Digital Visual Interface" (DVI) is a video display interface developed by the Digital Display Working Group (DDWG)
- "The digital interface is used to connect to a video source, such as a video display controller to a display device, such as a computer monitor." (Wikipedia)
- HDMI ("High Definition Multimedia Interface") is a proprietary audio/video interface for transferring uncompressed video data and compressed or uncompressed digital audio data from
an HDMI-compliant source device
- The display controller connects to a compatible computer monitor, video projector, digital television, or digital audio device
- "HDMI is a digital replacement for analog video standards." (Wikipedia)
- Stands for "Synchronous Dynamic Random Access Memory"
- SDRAM "is any DRAM where the operation of its external pin interface is coordinated by an externally supplied clock signal." (Wikipedia)
- "DRAM integrated circuits (ICs), between the mid-1970s and mid-1990s typically had an asynchronous interface, where responses to changes in control signal inputs occur as
soon as they are received."
Northbridge and Southbridge
- These are two chips in the core logic chipset architecture on a motherboard
- The northbridge is connected directly to the CPU and is responsible for tasks that require the highest performance
- (RAM and PCIe connect to northbridge)
- Southbridge is connected to the northbridge and from there connects to the CPU; it handles various I/O components, PCI bus, LPC bus (leading to the BIOS), etc.
Figure 21: Northbridge, southbridge, and the components they respectively connect to
2016-2020 Leo Coroneos
Certificate IV in Information Technology
South Regional TAFE, Albany WA Australia