An expansion slot, expansion bus or "slot" is an element that can enter
within it, other devices called expansion cards (cards that are inserted
into the expansion slot and give more benefits to computer equipment),
while that the definition of its Intel ® connector is a port due to its
characteristics, so it is not yet determined what type it is.
AGP comes from
the initials of ("Accelerated Graphics Port") or port graphics
accelerator. This type of slot-port was developed by Intel ® and
launched in 1997 exclusively for graphics support.
The bits in the
expansion slots mean the data capacity that is capable of providing this
information is important because by using a formula, it is possible to
determine the maximum transfer slot or expansion card. This is described
in the section: Bus and AGP data bus of this page.
Currently competes in the market against PCI and PCI-Express slots.
Figure 1. Slot - port AGP.
General features AGP
AGP is considered an expansion slot,
but not within the category but rather a port.
It is a slot that takes up very little
space on the main board (motherboard) measures only 8 cm. in length.
It is connected to the expansion
slots, so it does not share resources and streamline operations.
It has the ability to access directly
to the chipset (device that adapts the speed of microprocessors with the
cards) and therefore get higher performance.
Integra insurance that allows better
fixation of the graphics accelerator card into the slot.
The AGP bus connects directly to the
FSB ("Front Side Bus") of the microprocessor and uses the same frequency
with a bandwidth higher.
It integrates a data
capacity of 32 bits.
It has a transfer rate of
267 Mbytes / s (MB / s) up to 2000 respectively.
They have a working
internal speed of 66 MHz
There are several
versions of this slot (1X, 2X, 4X and 8X).
It has a feature called
DMA ("Direct Memory Access") allowing you to work directly with the
devices and RAM memory without involving the microprocessor.
AGP bus and data bus
The bus is a set of power lines that integrates the device to
communicate with other computer components. There are several types of
bus, because each device needs to send different types of information,
among them are the following:
we have a figure that will be saved in RAM.
Address Bus: is
responsible for determining exactly where in memory the data is
handles the timing and form of writing the data.
Data Bus: is
responsible for sending the data.
The most commonly used to describe the characteristics of the data bus
and AGP bus performance is a function of the speed of the device and its
- Example: If an 8X AGP slot works indicates that 32 bits
and has a working frequency of 66 MegaHertz (Hz), then transfer rate
calculated as follows:
to calculate the transfer rate of AGP slot
Method of calculation
Data rate =
(Data (by the value of X)) X Operating Frequency
Data rate = (
#bits * value of X / 8 ) X Operating Frequency bytes/segundo
Replacing Hz data
processed in bytes/s
Data rate = (
32 bits (8) / 8 ) X 66,000,000 bytes/s
Bits become bytes
Data rate = ( 32 ) X 66,000,000 bytes/s
Result in bytes/second
Data rate = 2,112,000,000 bytes/second
It makes Megabytes/s
Data rate = 2,112,000,000 bytes/second / 1,048,576 bytes
Final results and
Data rate = 2014.1 MB/s ó 2.01 GB/s
Calculation of the transfer rate
Based on the above formula we have the following baud rates and their
3.3 V (Volts)
1 GB (Gigabyte/second)
3.3 V ó
0.7 V ó
Keep in mind that each version is compatible with the former but not in
reverse, so it is possible to use graphics accelerators 1X, 2X, 4X 8X,
8X card but not a port 4X or 2 X.
Basically consists of a slotted plastic piece on the connectors which
are small, is is welded to the top of the main board. Showing 3 versions
of AGP voltage according to the position of the notch:
Figure 2. Scheme 3.3
volts AGP slot.
Figure 3. Scheme 1.5
volts AGP slot.
Figure 4. Scheme of the AGP slot for any
card into the AGP slot
The cards designed for the AGP slot is only the graphics accelerator
Graphics Accelerator Card, marks ASUS ®, GPU ATI Radeon ® model 9600PRO,
128 MB memory, 8X connector, VGA / DVI / S-Video.
use of AGP
It is used exclusively to provide greater capabilities to the computer
graphics, this is to increase the deployment during the execution of
video games. In fact there are 3 versions of this port, there has been
much confusion, since the cards can be or not compatible.
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