| A | B |
|---|
| Accelerated graphics port (AGP) | 34/64-bit expansion slot designed by Intel specifically for video that runs at 66 MHz and yields a throughput of at least 254 Mbps. Later versions (2x, 4x, 8x) give substantially higher throughput |
| Bus mastering | Circuitry allowing devices to avoid conflicts on the external data bus |
| COM ports | Serial communications ports available on your computer. When used as a program extension, .COM indicated a executable program file limited to 64KB |
| Device driver | Program used by the operating system to control communications between the computer and peripherals |
| Direct memory access (DMA) | Technique that some PC hardware devices use to transfer data to and from the memory without using the CPU |
| DMA controller | Resides between the RAM and the devices and handles DMA requests |
| Expansion bus | Set of wires going to the CPU, governed by the expansion bus crystal, directly connected to expansion slots of varying types (PCI, AGP, PCIe, etc). Depending on the type of slots, the expansion bus runs at a percentage of the main system speed. |
| Expansion bus crystal | Controls the speed of the expansion bus |
| Expansion slots | Connectors on a motherboard that enable users to add optional components to a system |
| Hexadecimal | Base-16 numbering system using 10 digits (0 through 9) and six letters (A through F). In the computer world, shorthand way to write binary numbers by substituting one hex digit for a four-digit binary number |
| I/O address | The CPU gives a command to a device by using a pattern of ones and zeros |
| I/O addressing | Using the address bus to talk to system devices |
| I/O advanced programmable interrupt controller (IOAPIC) | Typically located in the Southbridge, the IOAPIC acts as the traffic cop for interrupt requests to the CPU |
| I/O base address | First value in an I/O address range |
| Industry Standard Architecture (ISA) | Industry Standard Architecture design was found in the original IBM PC for the slots that allowed additional hardware to be connected to the computer’s motherboard. An 8-bit, 8.33-MHz expansion bus was designed by IBM for AT computer and released to the public domain. An improved 16-bit bus was also released to the public domain. An improved 16-bit bus was also released to the public domain. Replaced by PCI in the mid-1990s |
| Interrupt request (IRQ) | Signal from a hardware device, such as a modem or a mouse, indicating that it needs the CPU’s attention. In PCs, IRQs are sent along specific IRQ channels associated with a particular device. IRQ conflicts |
| Interruption | Suspension of a process, such as the execution of a computer program, caused by an event external to the computer and performed in such a way that the process can be resumed. Events of this kind include sensors monitoring laboratory equipment or a user pressing an interrupt key. |
| LPT ports | Commonly referred to as a printer port; usually associated with a local parallel port |
| Memory addressing | Taking memory address from system RAM and using it to address nonsystem RAM or ROM so the CPU can access it. |
| Microsoft Windows Logo Program | Testing program for hardware manufacturers, designed to ensure compatibility with the Windows OS. |
| Mini-PCI | Specialized form of PCI designed for use in laptops |
| PC bus | Original 8-bit expansion bus developed by IBM for PCs; ran at a top speed of 4.77 MHz. Also known as the XT bus |
| PCI express (PCIe) | serialized successor to PCI and AGP, which uses the concept of individual data paths called lanes. May use any number of lanes. Although single lanes (x1) and 16 lanes (x16) are the most common on motherboards |
| PCI extended (PCI-X) | Enhanced version of PCI, 64 bits wide. Typically seen in servers and high-end systems |
| Peripheral component interconnect (PCI) | Design architecture for the expansion bus on the computer motherboard, which enables system components to be added to the computer. Local bus standard, meaning that devices added to a computer through this port will use the processor at the motherboard’s full speed (up to 33 MHz) rather than at the slower 8 MHz speed of the regular bus. Moves data 32 or 64 bits at a time rather than the 8 or 16 bits the older ISA buses supported. |
| System resources | In classic terms, the I/O addresses, IRQs, DMA channels, and memory addresses. Also refers to other computer essentials such as hard drive space, system RAM, and processor speed. |
| Unsigned driver | Driver that has not gone through the Windows Hardware Quality Labs or Microsoft Windows Logo Program to ensure compatibility |
| Windows Hardware Quality Labs (WHQL) | submit the device for further testing |
| XT bus | Original 8-bit expansion bus developed by IBM for PCs; ran at a top speed of 4.77 MHz. |
