A disk cache is a software technique of speeding data access times. Copies of recently accessed disk sectors are stored in memory to a reserved area called cache RAM. When the executing program or the operating system requests to read a sector from the disk, the disk caching software checks to see if the sector is stored in cache RAM. If it is, the sector is retrieved from RAM and returned; no disk access is required. If the desired sector is not in cache RAM, the software reads the requested sector from the disk, stores it in cache RAM, and returns it to the program. When the info is found in the cache, it's a hit. When the info must be retrieved from the disk, it's a miss. Some disk caching programs also check for sector writes.
An area of computer memory where datat is temporarily stored on its way to or from a disk. A disk cache program can significantly speed up most disk operations. DOS contains the disk cache driver SMARTDRV.SYS, and OS/2 provides CACHE if you are using the high performance file system, or DISKCACHE if you are using the file allocation table system. Disk cache programs are also available from other third party sources.