Advanced SCSI Programming Interface

Computer software for connecting SCSI devices

The Advanced SCSI Programming Interface (ASPI) is a programming interface developed by Adaptec which standardizes communication on a computer bus between a SCSI driver module and SCSI (and ATAPI) peripherals.[1]: 55–56 [2]

## Structure

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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.[1]: 56

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).[1]: 57

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).[1]: 233 ASPI supports concurrent execution of SCSI commands.[3]: 231

## History

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ASPI was developed by Adaptec around 1989[4] and was formally introduced in January 1990. Originally supporting only MS-DOS,[5] support for NetWare was added in 1991, while support for OS/2 and Windows 3.x was added in 1992.[4][6] Originally developed only for SCSI devices, support for ATAPI devices was added later.[7]: 772 Most other SCSI host adapter vendors (for example BusLogic, DPT, AMI, Future Domain, DTC) shipped their own ASPI managers with their hardware.[8]

Adaptec also developed generic SCSI disk and CD-ROM drivers for DOS (ASPICD.SYS and ASPIDISK.SYS).[3]: 60–61

At least a couple of other programming interfaces for SCSI device drivers competed with ASPI in the early 1990s, including CAM (Common Access Method), developed by Apple; and Layered Device Driver Architecture, developed by Microsoft. However, ASPI was far and away more common than any of its competitors in this space, with PC Magazine declaring it a de facto standard for developing SCSI device drivers only two years after its introduction.[9]

Starting in 1995, Microsoft licensed the interface for use with their Windows 9x operating systems. 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.[10]

To support USB drives under DOS, Panasonic developed a universal ASPI driver (USBASPI.SYS) that bypasses the lack of native USB support by DOS.[11]

## Drivers

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Examples of ASPI drivers:

Operating system  | Driver filename  | Bundled

|
|

MS-DOS  | ASPI4DOS.SYS or USBASPI.SYS (USB drives only)  | No
Windows 3.1x  | WINASPI.DLL | No
Windows 95, 98 and ME | WNASPI32.DLL, WINASPI.DLL, APIX.VXD and ASPIENUM.VXD | Yes
Windows NT, 2000, XP  | WNASPI32.DLL, ASPI32.SYS | No

## See also

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* SCSI Pass-Through Direct (SPTD)

## References

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1. ^ a b c d Sawert, Brian (1998). The Programmer's Guide to SCSI. Addison-Wesley. pp. 55–102, 233. ISBN 0201185385 - via Google Books.
2. ^ White, Myles (May 25, 1995). "Getting your components to work together, part II". The Toronto Star: H3 - via Newspapers.com.
3. ^ a b Ridge, Peter M. (1995). The Book of SCSI: A Guide for Adventurers. No Starch Press. ISBN 9781886411029 - via Google Books.
4. ^ a b Spain, Patrick J.; James R. Talbot, eds. (1995). Hoover's Handbook of Emerging Compaies 1995: Profiles of America's Most Exciting Growth Enterprises. The Reference Press. p. 118\. ISBN 9781878753755 - via Google Books.
5. ^ Brownstein, Mark (January 15, 1990). "Adaptec Unveils SCSI Interface Standard". InfoWorld. 12 (3). IDG Publications: 23 - via Google Books.
6. ^ Guzman, Ed (June 1992). "ASPI Refines SCSI I/O Routing". Computer Technology Review. 12 (7). West World Publications: 22. ProQuest 220619290.
7. ^ Mueller, Scott (2003). Upgrading and Repairing PCs (14th ed.). Que. pp. 563–564, 771–772\. ISBN 9780789727459 - via Google Books.
8. ^ Myers, Ben (May 1994). "More on ASPI". Dr. Dobb's Journal. 19 (5). UBM LLC: 10. Archived from the original on November 25, 2024.
9. ^ Thomas, Susan G. (April 28, 1992). "SCSI Protocol Wars: ASPI, CAM, LADDR". PC Magazine. 11 (8). Ziff-Davis: 31 - via Google Books.
10. ^ Tewell, Thomas (December 1997). "Writing Portable Win32 SCSI Applications". Dr. Dobb's Journal. 22 (12). UBM LLC: 56–57\. Archived from the original on December 18, 2014.
11. ^ 软件安装完全手册 [Complete Software Installation Manual] (in Chinese). Science Press. 2006. p. 130\. ISBN 978-7-03-018123-7 - via Google Books.