Advanced SCSI Programming Interface
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In computing, ASPI (Advanced SCSI Programming Interface) is an Adaptec-developed programming interface which standardizes communication on a computer bus between a SCSI driver module on the one hand and SCSI (and ATAPI) peripherals on the other.
The ASPI manager software provides an interface between ASPI modules (device drivers or applications with direct SCSI support), a SCSI host adapter, and SCSI devices connected to the host adapter. The ASPI manager is specific to the host adapter and operating system; its primary role is to abstract the host adapter specifics and provide a generic software interface to SCSI devices.
On Windows 9x and Windows NT, the ASPI manager is generic and relies on the services of SCSI miniport drivers. On those systems, the ASPI interface is designed for applications which require SCSI pass-through functionality (such as CD-ROM burning software).
The primary operations supported by ASPI are discovery of host adapters and attached devices, and submitting SCSI commands to devices via SRBs (SCSI Request Blocks). ASPI supports concurrent execution of SCSI commands.
ASPI was developed by Adaptec around 1990. It was initially designed to support DOS, OS/2, Windows 3.x, and Novell NetWare. It was originally written to support SCSI devices; support for ATAPI devices was added later. Most other SCSI host adapter vendors (for example BusLogic, DPT, AMI, Future Domain, DTC) shipped their own ASPI managers with their hardware.
Adaptec also developed generic SCSI disk and CD-ROM drivers for DOS (ASPICD.SYS and ASPIDISK.SYS).
Microsoft licensed the interface for use with Windows 9x series. At the same time Microsoft developed SCSI Pass Through Interface (SPTI), an in-house substitute that worked on the NT platform. Microsoft did not include ASPI in Windows 2000/XP, in favor of its own SPTI. Users may still download ASPI from Adaptec. A number of CD/DVD applications also continue to offer their own implementations of ASPI layer.
ASPI was provided by the following drivers.
|Operating System||Driver Filename||Bundled|
|Windows 95, 98 and ME||WNASPI32.DLL, WINASPI.DLL, APIX.VXD and ASPIENUM.VXD||Yes|
|Windows NT, 2000, XP||WNASPI32.DLL, ASPI32.SYS||No|
SCSI is available in a variety of interfaces. The first, still very common, was parallel SCSI (now also called SPI), which uses a parallel bus design. As of 2008, SPI is being replaced by Serial Attached SCSI (SAS), which uses a serial design but retains other aspects of the technology. Many other interfaces which do not rely on complete SCSI standards still implement the SCSI command protocol; others (such as iSCSI) drop physical implementation entirely while retaining the SCSI architectural model. iSCSI, for example, uses TCP/IP as a transport mechanism. SCSI interfaces have often been included on computers from various manufacturers for use under Microsoft Windows, Mac OS, Unix, Commodore Amiga and Linux operating systems, either implemented on the motherboard or by the means of plug-in adaptors. With the advent of SAS and SATA drives, provision for SCSI on motherboards is being discontinued. A few companies still market SCSI interfaces for motherboards supporting PCIe and PCI-X.