Microsoft KB Archive/42860

Enhanced Functionality of FASTOPEN.EXE in MS-DOS 4.00 and 4.01 PSS ID Number: Q42860 Article last modified on 02-04-1993 PSS database name: O_MSDOS

4.00 4.01

MS-DOS

Summary:

The FASTOPEN command has been enhanced in Versions 4.00 and 4.01 of MS-DOS through the addition of extent caching and Lotus/Intel/Microsoft (LIM) 4.0 expanded memory support. For more information on the specifics of these additions, see below. The syntax for FASTOPEN.EXE in MS-DOS 4.00 and 4.01 is as follows:

FASTOPEN d:{=[n | (n,m)}… /x

where

d: Drive letter to process

n Number of file and directory entries for the name cache for Drive D. The range of values for file and directory entries is 10 to 999, with a default of 10.

m Number of extent entries for files on Drive D. If omitted, the extent feature is not provided. The range of values for extent entries is 1 to 999.

/x Indicates cache will be placed in LIM 4.0 expanded memory.

More Information:

FASTOPEN.EXE provides two different types of caching. The first is file and directory name caching, and the second is file extent caching.

File and directory name caching keeps track of the most recently opened files and their locations on the disk. This allows quicker access to files when they are opened. This works for both files and directories, so accessing files from the same directory is also much faster when using FASTOPEN. Every file or directory that FASTOPEN tracks requires approximately 48 bytes of memory.

Extent caching is the new feature to MS-DOS 4.00 and 4.01 FASTOPEN. With extent caching, FASTOPEN keeps track of all of the different parts of a file and where the different parts of the file are located on the disk. This avoids a lot of the overhead involved with file opens, reads, and writes, as MS-DOS does not have to look on the disk to find out where the different parts of the file are located. Each extent that FASTOPEN tracks for each file requires approximately 16 bytes of memory.

Additional reference words: 4.00 4.01 noupd

Copyright Microsoft Corporation 1993.