Glossary (Scanner)

ASPI: Advanced SCSI Programming Interface, a specification thatAdaptec developed and that programmers can use to write device drivers and otherprograms that communicate with devices such as scanners. ASPI defines a commonset of communications that can be sent from SCSI devices to host adapters tocarry out tasks such as data transfer.

ASPI layer: A standard software interface between the ASPI devicedrivers and the ASPI software manager, which programmers write for a specifichost adapter. Commands from the ASPI device drivers pass through the ASPI layer.

ASPI software manager: Also called the ASPI manager; a programtailored for a specific host adapter and operating system that interpretscommands from ASPI devices and relays this information to the host adapter. ASPIsoftware managers are sometimes called system-level drivers.

Device driver: A program that controls a piece of hardware, such asa scanner. Scanners usually require two drivers to work: one for the hostadapter and a second to control the scanner. The host-adapter driver is oftencalled a system-level driver (usually a *.sys file); the scanner driver iscalled a source driver. Source drivers that comply with the ASPI specificationsare called ASPI device drivers.

Host adapter: Hardware that lets the computer communicate (usingsoftware such as ASPI managers and device drivers) with the SCSI device. Hostadapters can be either a printed circuit board card or a built-in bus on thesystem motherboard.

ISIS: Image and Scanner Interface Standard, an API for the designand development of scanner drivers. Developed by Pixel Translations and nowadopted by other vendors, ISIS is an alternative to the TWAIN standard,specifically for scanners. The ISIS standard is usually used for opticalcharacter recognition (OCR) software.

SCSI: Small Computer Systems Interface, a standard developed in thelate 1980s. It lets up to seven SCSI devices be daisy-chained onto a single SCSIbus. The most common standard is SCSI-2, which was finalized in 1992 and amongother things, added support for CD-ROMs and scanners.

SCSI devices: Peripherals such as disk drives, CD-ROM drives,scanners, and tape drives.

TWAIN: An image and scanner interface standard for the design anddevelopment of scanner drivers. TWAIN is an alternative to the ISIS standard.