TYAN THUNDER K8QE Manual page 68

of 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 4GB of regular memory.
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): chips that hold the basic
startup information for the BIOS.
COM port: another name for the serial port, which is called as such 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).
DDR (Double Data Rate): a technology designed to double the clock speed of the
memory. It activates output on both the rising and falling edge of the system clock rather
than on just the rising edge, potentially doubling output.
DIMM (Dual In-line Memory Module): faster and more capacious form of RAM than
SIMMs, and do not need to be installed in pairs.
DIMM bank: sometimes called DIMM socket 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 that are similar to IRQs. DMA channels allow
hardware devices (like soundcards 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-n-Play devices will take care of
this for you.
DRAM (Dynamic RAM): widely available, very affordable form of RAM which looses data
if it is not recharged regularly (every few milliseconds). This refresh requirement makes
DRAM three to ten times slower than non-recharged RAM such as SRAM.
ECC (Error Correction Code or Error Checking and Correcting): allows data to be
checked for errors during run-time. Errors can subsequently be corrected at the same
time that they're found.
EEPROM (Electrically Erasable Programmable ROM): also called Flash BIOS, it is a
ROM chip which can, unlike normal ROM, be updated. This allows you to keep up with
changes in the BIOS programs without having to buy a new chip. TYAN's BIOS updates
can be found at http://www.tyan.com
ESCD (Extended System Configuration Data): a format for storing information about
Plug-n-Play devices in the system BIOS. This information helps properly configure the
system each time it boots.
Firmware: low-level software that controls the system hardware.
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