When the Cache Buffer becomes full, it will make room

for the most recently requested data by replacing the blocks that have been stored in the buffer the longest without being accessed. The Track Buffer is not variable; it is large enough to hold one track (6K) and cannot be changed.

When you call for information, the system first looks in the Cache Buffer. If the information is there, it reads it with speed comparable to (often even faster than) reads from RAM Disks and internal hard disks. If it doesn’t find the information in the Cache Buffer, it checks the Track Buffer. This takes very little more time than reading from the Cache Buffer because the system is still not required to read the disk drive.

If the information is not in the Track Buffer, the system will then go back out to the disk drive, find the information and read the entire track to the Track Buffer. This new track replaces the track currently held in the Track Buffer.

While this method actually goes through more steps than a non-cached system to get information that is not stored in the buffer, the actual time it takes the system to check the Cache Buffer and Track Buffer is insignificant.

Copy Protected Programs

Some copy protected programs have a disk accessing function of their own and cannot use the Cache. However, most programs will use the cache with no problem.

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