Tyan Computer S1854 - Manual (Page 68)

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68
Appendix
Glossary
data the bus, phone line, or other electrical path, can carry. Greater bandwidth,
then, also results in greater speed.
The BIOS (Basic Input/Output System) program resides in the ROM chip, and
provides the basic instructions for controlling your computer’s hardware. Both
the operating system and application software use BIOS routines to ensure
compatibility.
A buffer is a portion of RAM which is used to temporarily store data, usually
from an application, though it is also used when printing, and in most key-
board drivers. The CPU can manipulate data in a buffer before copying it, all at
once, to a disk drive. While this improves system performance--reading to or
writing from a disk drive a single time is much faster than doing so repeatedly--
there is the possibility of losing your data should the system crash. Informa-
tion stored in a buffer is temporarily stored, not permanently saved.
A bus is a data pathway. The term is used especially to refer to the connection
between the processor and system memory, and between the processor and
PCI or ISA local buses.
Bus mastering allows peripheral devices and IDEs to access the system
memory without going through the CPU (similar to DMA channels).
A cache is a temporary storage area for data that will be needed often by an
application. Using a cache lowers data access times, since the needed informa-
tion is stored in the SRAM instead of in the slower DRAM. Note that the
cache is also much smaller than your regular memory: a typical cache size is
512KB, while you may have as much as 1GB of regular memory.
Cache size refers to the physical size of the cache onboard. This should not be
confused with the cacheable area, which is the total amount of memory which
can be scanned by the system in search of data to put into the cache. A typical
setup would be a cache size of 512KB, and a cacheable area of 512MB. In this
case, up to 512MB of the main memory onboard is capable of being cached.
However, only 512KB of this memory will be in the cache at any given moment.
Any main memory above 512MB could never be cached.
Closed and open jumpers Jumpers and jumper pins are active when they are
On or Closed, and inactive when they are Off or Open.
CMOS Complementary Metal-Oxide Semiconductors are chips that hold the
basic start-up information for the BIOS.