TYAN TOMCAT K8S Manual page 55

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.
Form factor: an industry term for the size, shape, power supply type, and external connector type
of the Personal Computer Board (PCB) or motherboard. The standard form factors are the AT and
ATX.
Global timer: onboard hardware timer, such as the Real-Time Clock (RTC).
HDD: stands for Hard Disk Drive, a type of fixed drive.
H-SYNC: controls the horizontal synchronization/properties of the monitor.
TM
HyperTransport : a high speed, low latency, scalable point-to-point link for interconnecting ICs
on boards. It can be significantly faster than a PCI bus for an equivalent number of pins. It provides
the bandwidth and flexibility critical for today's networking and computing platforms while retaining
the fundamental programming model of PCI.
IC (Integrated Circuit): the formal name for the computer chip.
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