Glossary of Technical Terms
AC' 97:
AC'97 is a
device designed to include a digital processor for modem plus an
audio CODEC for analog I/O. These two parts are linked together
by AC'97 link bus. Putting the digital processor in the main
system chipset will reduce the cost of sound/modem onboard
solutions.
ACPI (Advanced
Configuration & Power Interface):
ACPI is developed
jointly by Intel, Microsoft and Toshiba. This interface provides
a channel for management of the PC system and its hardware (such
as CPU and BIOS), pushing PC power management to a more advanced
and user-friendly level.
AGP (Accelerated
Graphic Port):
AGP is a bus
interface for high performance
3D graphics. AGP
takes advantage of both the rising and falling edges of the
66MHz clock. For 2X AGP, the data transfer rate is
66MHz x 4byte x 2
= 528MB/s. AGP 4X mode is 66MHz x 4byte x 4 = 1056MB/s.
AMR (Audio/Modem
Riser):
AMR is an
interface to connect the CODEC circuit of AC'97 sound/ modem
solution to the mainboard through an AMR card and an AMR
connector.
APM (Advanced
Power Management):
APM is developed
by Intel and Microsoft and
intended for PC power management through the system BIOS. Through APM,
the PC power consumption can be reduced to 5W or lower.
UATA (Ultra AT
Attachment), ATA/66, ATA/100, ATA133:
ATA is the
specification of a disk drive interface that integrates the
controller on the disk drive itself with the IDE technology.
UATA/66
uses both
rising edge and falling edge to provide a data transfer rate of
16.6MB/s x4 = 66MB/s. You need special UATA/66 IDE cable to use
UATA/66.
UATA/100/133
also
uses both the rising edge and falling edge as ATA/66, but clock
cycle time is reduced to 40ns. The data transfer rate is (1/
40ns) x 2 bytes x 2 = 100MB/s. To use UATA/100/133, you need
special 80-wire IDE cable, the same as UATA/66.
ATAPI (AT
Attachment Packet Interface):
This is the
extension of the EIDE (extended
IDE) that enables the interface to support CD-ROM players and
tape drives.
BIOS (Basic
Input/Output System):
BIOS is a set of
assembly routine/program that resides in EPROM or Flash ROM.
BIOS controls Input/output devices and other hardware devices on
the motherboard.
Generally, the
operating system and drivers will access BIOS before accessing
hardware devices, to enhance the portability of the hardware
devices.
Bus Master IDE (DMA
mode):
An IDE interface is for mass storage devices in which the
controller is integrated in to the disk or CD-ROM itself.
To reduce the
workload of the CPU, the bus master IDE device transfers data
from/to memory without interrupting CPU and releases CPU to
operate concurrently while data is transferring between memory
and IDE device.
You need the bus
master IDE driver and the bus master IDE HDD to support bus
master IDE mode.
CAS (Column
Address Strobe):
CAS is a
technology of DRAM writes and reads. The number of clock cycles
of the CAS signals is dependent on the DRAM timing.
CMOS Chip
(Complementary Metal Oxide Semiconductor Chip):
CMOS Chip is built
on CMOS Technology with very low power requirements. The CMOS
Chip stores operating system data.
CNR (Communication
and Networking Riser):
CNR interface
provides a cost-reducing method of implementing LAN, home
networking, DSL, USB, wireless, audio and modem subsystems
through a CNR card and a CNR connector.
CODEC (Coder and
Decoder);
Normally, CODEC
means a circuit that can do digital to analog conversion and
vice versa. It is part of the AC'97 sound/modem solution.
DDR (Double Data
Rated) SDRAM;
DDR SDRAM
essentially doubles the memory speed of SDRAMs without
increasing the clock frequency.
DIMM (Dual In Line
Memory Module);
A DIMM socket is
built with a 168-pin assignment and supports 64-bit data. DIMM
can be single or double sided. The golden finger signals on each
side of the module are different; that is why it is called Dual
In Line. Almost all DIMMs are made with SDRAM now, which operate
at 3.3V. Some old DIMMs were made by FPM/EDO and only
operate at 5V.
DMA (Direct Memory
Access);
Channel for
communications between memory and surrounding devices.
ECC (Error
Checking and Correction):
The ECC algorithm
can detect double-bit errors and automatically correct
single-bit error while parity mode can only detect single-bit
error.
ECP (Enhanced
Communication Port):
ECP is a
technology designed to improve Input/Output for parallel ports.
EPP (Enhanced
Parallel Port):
EPP is a standard
that supports data transfer rates of up to 500 kps for parallel
printers
EDO (Extended Data
Output) Memory:
Unlike traditional
FPM (Fast Page Mode) memory that tri-states the memory output
data to start the pre-charge activity, EDO DRAM holds the memory
data valid until the next memory access cycle. This is similar
to pipeline effect in reducing one clock state.
EEPROM (Electronic
Erasable Programmable ROM):
Both EEPROM and
Flash ROM can be re-programmed by electronic signals, but the
interface technology is different. Size of EEPROM is much
smaller than flash ROM. BIOS is now generally stored in EEPROM
or Flash ROM.
EPROM (Erasable
Programmable ROM):
Traditional
mainboard stores BIOS codes in EPROM that can only be erased by
ultra-violet (UV) light. If BIOS has to be
updated, you need to remove the EPROM from the motherboard,
clear data by UV light, re-program and then insert it back in
the socket.
FC-PGA (Flip
Chip-Pin Grid Array):
FC means Flip
Chip, while FCPGA is a new package of Intel for Pentium III CPU.
It is compatible with SKT370 socket, but
requires the mainboard to add some signals on socket 370.
Flash ROM:
Flash ROM can
be re-programmed by electronic signals. It is easier for BIOS to
upgrade by a flash utility, but it is also easier to be infected
by some viruses. Because of the increase of new functions, BIOS
size is increased from 64KB to 256KB (2M bit) or more.
FSB (Front Side
Bus):
FSB is the data channel connecting the Processor to chipset,
RAM, mainboard busses, AGP socket etc. Its speed is rated in MHz
and is talked of as "FSB clock".
FSB Clock means
CPU external bus clock.
CPU internal clock
= CPU FSB Clock x CPU Clock Ratio.
IEEE 1394:
IEEE 1394 is a
low-cost digital transfer interface with transfer rated at 100,
200 or 400 Mbps. It provides
solutions for connecting digital television devices and Serial
Bus Management. There
are two type of IEEE 1394 data transfer: asynchronous and
isochronous.
Isochronous data
channels provide guaranteed data transport at a predetermined
rate. This is especially important for time-critical multimedia
data where just-in-time delivery eliminates the need for costly
buffering.
Parity Bit:
The parity bit
mode of error detection uses 1 parity bit for each byte. Normally it is
even parity mode; each time the memory data is updated, the
parity bit will be adjusted to have an even count "1" for each
byte. Next time the memory is read with odd number of "1", the
parity error has occurred. This is called
single bit error detection.
PC-100 DIMM:
SDRAM
DIMM that supports 100MHz CPU FSB bus clock.
PC-133 DIMM:
SDRAM
DIMM that supports 133MHz CPU FSB bus clock.
PC-1600 or PC-2100
DDR SDRAM:
PC-1600 DDR SDRAM
with a 64-bit data bus doubles the data transfer rate of PC100
SDRAM and provides data transfer bandwidth up to
100x64/8x2=1600MB/s. PC2100 DDR SDRAM doubles the data transfer
rate of PC-133, providing data transfer bandwidth up to
133x64/8x2=2100MB/s.
PCI (Peripheral
Component Interface) Bus:
A high-speed data
channel for the internal connection of peripheral devices and
the computer system through a PCI expansion card.
PnP (Plug and
Play):
The PnP specification is a standard register interface for both
BIOS and operating system (such as Windows 95).
These registers
are used by BIOS and the operating system to configure system
resources and prevent conflicts. PnP BIOS or operating system
will automatically allocate the IRQ/DMA/Memory.
Currently, most
PCI cards and most ISA cards are PnP compliant.
POST (Power-On
Self Test);
The BIOS self test
procedure after power-on. It is generally
the first or the second program shown on your monitor screen
during system boot.
RAID (Redundant
Array of Independent Disks);
A group of hard
disks set up in a PC system for data fault tolerance and better
performance. RAID is used more in servers than in personal
computers. Different levels of RAID are for different functions
and performance requirements:
• RAID 0
provides data striping (spreading out blocks of files across
multiple disks), and improves performance but not fault
tolerance.
• RAID 1
provides disk mirroring for data backup.
• RAID
0+1
provides a dedicated disk for error correction of data which
means better performance and some fault tolerance.
RAS (Row Address
Strobe):
RAS is a
technology where DRAM writes to and reads the Row addresses,
while a CAS (Column Address Strobe) signal is used to validate
the column address.
The signals are
generally sent CAS before RAS. (In the Network field, RAS stands
for Remote Access Services).
RDRAM (Rambus
DRAM):
Rambus DRAM is a memory technology that uses large burst mode
data transfer of up to 1.6GHz.
RDRAM technology
helps to set up a system level improvement, not just a component
upgrade.
RIMM (Rambus
Inline Memory Module):
RIMM is built with
a 184-pin architecture module that supports RDRAM memory
technology. A RIMM memory module may contain up to maximum of 16
RDRAM devices.
SDRAM (Synchronous
DRAM):
SDRAM is one of the Dynamic Random
Access Memory
(DRAM) technologies that allow DRAM to use the same clock as the
CPU host clock (EDO and FPM are asynchronous and do not have a
clock signal). SDRAM comes in 64-bit 168-pin DIMM and operates
at 3.3V.
SIMM (Single In
Line Memory Module):
SIMM socket is
only 72-pin and only single sided. The golden finger signals on
each side of the PCB are identical. That is why it is called
Single In Line. SIMM is made of FPM or EDO DRAM and supports
32-bit data. SIMM for mainboard design is being phased out.
SPD (Serial
Presence Detect):
SPD is a small ROM
or EEPROM device resided on the DIMM or RIMM. Memory module
information such as DRAM timing and
chip parameters can be stored in SPD so that the BIOS can access
it and use it to decide the best timing for this DIMM or RIMM.
UART (Universal
Asynchronous Receiver/transmitter):
UART is built in a
chip that controls the data sent to and received from a serial
port. A 16550 UART is now
standard in most PCs. This supports modem speed up to 57,600 bps and
beyond, and direct connect speed of 115,200 bps.
Many UARTs have
built-in errors in the internal code and do not work correctly
with many external modems. UART is also found as the serial
interface on internal modems.
Ultra DMA:
Ultra DMA (or,
more accurately, Ultra DMA/33) is a protocol for transferring
data at 33.3MB/s between a hard disk drive through the
computer's data path (or bus) to the computer's random access
memory (RAM). The transfer data
is twice as fast as the previous Direct Access Memory (DMA) interface.
Ultra DMA technology has advanced to Ultra DMA/66 and Ultra DMA/100.
16.6MB/s x2 =
33MB/s 16.6MB/s x4 = 66MB/s
16.6MB/s x6 =
100MB/s.
USB (Universal
Serial Bus):
USB is a 4-pin
serial peripheral bus that is capable of cascading low/medium
speed peripherals (less than 10 Mbit/s) such as keyboard, mouse,
joystick, scanner, printer and modem.
VCM (Virtual
Channel Memory):
NEC's Virtual
Channel Memory
(VCM) is a new
DRAM core architecture that dramatically improves the memory
system's ability to service multimedia requirements.
VCM increases
memory bus efficiency and performance of any DRAM technology by
providing a set of fast static registers between the memory core
and 1/O pins.
Using VCM
technology results in reduced data access latency and reduced
power consumption.
VRM (Voltage
regulator Module):
This is a small
module installed on a mainboard to
regulate the voltage fed to the processor on board. Voltage
regulation can be built on board in various ways.
VRM is a socketed
type of regulator module that is easier to change when needed.
Zero Wait State:
When
memory is operating at its fastest speed in the course of
fetching and yielding data, it allows no "no-op" cycle; this is
called a zero wait state.
On the other hand,
when a memory is in a wait state after it gets a command to
fetch data, it waits for one , two or more cycles to assure that
the expected data is in the buffer.
ZIP file:
a patented type of compressed file used with Iomega Zip Drives.
Zoom:
make a window or
screen larger or smaller in the Graphical User Interface of a
computer system. Usually, to "zoom in" means to enlarge, and to
"zoom out" means to reduce the displayed size of objects.
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