User's Manual

Glossary
BIOS
Acronym for “Basic Input Output System”.
Bit
Short for “binary digit”, the smallest unit of information in
the binary number system. Corresponds to one storage cell. A
bit can either have the value 0 or 1. Eight bits are equal to one
byte. The terms “bit” and “binary digit” were coined in 1946
at Princeton University by the mathematician John Tukey,
one of the most important staticians of the 20
th
century. Tukey
had a particular talent for coining terms, he also created the
term “software”.
Byte
A byte is the smallest addressable unit of memory. It consists
of eight bits. As a bit can have one of two values, one byte
allows 256 combinations (two to the power of eight), and can
therefore represent 256 different conditions or characters.
Cache
A fast form of memory that temporarily stores data for rapid
access. There are different kinds of caches:
- Caches that store data from main memory in the immediate
vicinity of the CPU (L1/L2 cache).
- Caches that store data from the hard disk in the main
memory (such as Smartdrive or smartdrv.exe).
- Caches that store data from slow CD-ROM drives on the
hard disk.
The hard disk cache stores write and read accesses in the disk
hardware. Depending on the model, a hard disk sold in 2000
has a cache between 128 and 4096 KB; EIDE disks frequently
have a 512 KB cache, while SCSI disks often have a 1024 KB
cache. As the algorithms used vary in their effectiveness, a
larger cache does not necessarily make a disk faster. If the
data in the cache is needed again, the cache accelerates
operations because the data does not have to be read from the
slower disk again.
114 TuneUp Utilities 2004