SCI System control interrupt. A system interrupt used by hardware to notify the operating system of ACPI events. The SCI is an active low, shareable, level interrupt.
SCSI Small computer system interface, pronounced “scuzzy.” An I/O bus designed as a method for connecting several classes of peripherals to a host system without requiring modifications to generic hardware and software.
sealed case A PC system design that does not provide end-user–accessible internal expansion slots. This is the equivalent of “no user-serviceable parts inside” for consumer appliances. A sealed case can provide external expansion capabilities.
SECAM Sequential Couleur a Memoire (Sequential Color with Memory). The television standard for France, Russia, and most of Eastern Europe. As with PAL, SECAM is based on a 50-Hz power system, but it uses a different encoding process and displays 819 horizontal lines per frame at a scan rate of 25 frames per second (50 fields per second). See also NTSC and PAL format.
SIPC Simply Interactive PC. A vision guiding investments that Microsoft is making in software and hardware advances to make the PC as simple, convenient, and approachable as an appliance.
SMBus System Management Bus. A two-wire interface based on the I²C protocol. The SMBus is a low-speed bus that provides positive addressing for devices, as well as bus arbitration.
software device A filter in kernel streaming and DirectShow (formerly ActiveMovie) that has no underlying hardware associated with it.
software modem Also host-based signal processing or pumpless modem. Performs signal processing on the host CPU, and implements the controller using V.42bis. The modem hardware consists of a telephone-line interface and digital-to-analog and analog-to-digital conversion circuitry. The hardware does not contain a DSP or a microcontroller. Compare with controllerless modem.
Sound Blaster Hardware produced by Creative Labs, Inc., that represents for MS-DOS–based games one of the major hardware interfaces for both audio and music (specifically MIDI) data.
SPI Service Provider Interface. Component in Microsoft networking, TAPI, and other communications technologies.
spin down A power-management capability in which a hard drive shuts down its spindle motor.
Still Image architecture Also STI. A WDM architecture for still-image devices. A still-image minidriver provides support for still-image devices such as scanners and cameras under the WDM Still Image architecture.
SVGA Super VGA. A video standard established by VESA to provide high-resolution color display on IBM-compatible computers. The most common SVGA standard is 1024 × 768 pixels resolution.
S-Video Also Y/C video. A video signal that separates the luminance and color (Y and C) components of the signal for improved quality over composite video. The type of video signal used in the Hi8 and S-VHS videotape formats. Transmits luminance and color portions separately, using multiple wires, thus avoiding the NTSC encoding process and its inevitable loss of picture quality.
system board Also motherboard or planar. The primary circuit board in a PC that contains most of the basic components of the system.
system devices Devices on the system board, such as interrupt controllers, keyboard controller, real-time clock, DMA page registers, DMA controllers, memory controllers, FDC, IDE ports, serial and parallel ports, PCI bridges, and so on. These devices are typically integrated into the supporting chip set.