ASPI: Advanced SCSI Programming Interface, a specification that
Adaptec developed and that programmers can use to write device drivers and other
programs that communicate with devices such as scanners. ASPI defines a common
set of communications that can be sent from SCSI devices to host adapters to
carry out tasks such as data transfer.
ASPI layer: A standard software interface between the ASPI device
drivers and the ASPI software manager, which programmers write for a specific
host adapter. Commands from the ASPI device drivers pass through the ASPI layer.
ASPI software manager: Also called the ASPI manager; a program
tailored for a specific host adapter and operating system that interprets
commands from ASPI devices and relays this information to the host adapter. ASPI
software managers are sometimes called system-level drivers.
Device driver: A program that controls a piece of hardware, such as
a scanner. Scanners usually require two drivers to work: one for the host
adapter and a second to control the scanner. The host-adapter driver is often
called a system-level driver (usually a *.sys file); the scanner driver is
called a source driver. Source drivers that comply with the ASPI specifications
are called ASPI device drivers.
Host adapter: Hardware that lets the computer communicate (using
software such as ASPI managers and device drivers) with the SCSI device. Host
adapters can be either a printed circuit board card or a built-in bus on the
system motherboard.
ISIS: Image and Scanner Interface Standard, an API for the design
and development of scanner drivers. Developed by Pixel Translations and now
adopted by other vendors, ISIS is an alternative to the TWAIN standard,
specifically for scanners. The ISIS standard is usually used for optical
character recognition (OCR) software.
SCSI: Small Computer Systems Interface, a standard developed in the
late 1980s. It lets up to seven SCSI devices be daisy-chained onto a single SCSI
bus. The most common standard is SCSI-2, which was finalized in 1992 and among
other 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 and
development of scanner drivers. TWAIN is an alternative to the ISIS standard.