TYAN TOMAHAWK BX Manual page 78

Appendix 2
Glossary
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
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.
COM port
The is another name for the serial port, which is so-called
because it transmits the eight bits of a byte of data along one wire, and
receives data on another single wire (that is, the data is transmitted in serial
form, one bit after another). Parallel ports transmit the bits of a byte on eight
different wires at the same time (that is, in parallel form, eight bits at the same
time).
DIMM
Dual In-line Memory Modules are a faster and more capacious form
of RAM than SIMMs, and do not need to be installed in pairs.
DIMM bank
DIMM banks are sometimes called DIMM sockets, because
the physical slot and the logical unit are the same. That is, one DIMM
module fits into one DIMM socket, which is capable of acting as a memory
bank.
DMA
Direct Memory Access channels are similar to IRQs. DMA channels
allow hardware devices (like sound cards or keyboards) to access the main
memory without involving the CPU. This frees up CPU resources for other
tasks. As with IRQs, it is vital that you do not double up devices on a single
line. Plug and Play devices will take care of this for you.
Doze mode
In , only the CPU's speed is slowed.
DRAM
Dynamic RAM is a widely available, very affordable form of RAM
which has the unfortunate tendency to lose data if it is not recharged regu-
larly (every few milliseconds). This refresh requirement makes DRAM three to
ten times slower than non-recharged RAM such as SRAM.
Jumpers and jumper pins are active when they
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