Agp Universal Slot
Posted : admin On 7/29/2022The AGP slots In fig 1.1 is a typical AGP Pro Universal slot on a motherboard. We have pointed out the alignment keys, which, in conjunction with the alignment notches on the AGP/AGP Pro video card ensures the card is installed correctly. The two extensions we have pointed out are used to provide extra power to the AGP Pro cards. When an AGP Universal card is plugged-into an AGP Universal slot, only the 1.5 V portion of the card is used. Some cards, like Nvidia's GeForce 6 series (except the 6200) or ATI's Radeon X800 series, only have keys for 1.5 V to prevent them from being installed in older mainboards without 1.5 V support. AGP Pro is a physical specification aimed at satisfying the needs of high-end graphics card manufacturers, who are currently limited by the maximum electrical power that can be drawn by an AGP card (about 25W). AGP Pro caters for cards that draw up to 100W, and will use a slightly longer AGP slot that will also take current AGP cards. AGP Graphics Slot. So What is the AGP Graphics Slot? Read Below So just what exactly is an AGP graphics slot? The initials ‘AGP’ are an abbreviation of the term ‘Accelerated Graphics Port’, which is the commonly used term for describing a specific point to point video card interface that is used to connect the card to your computer’s processor and memory. Version 2.0 of AGP was powered by 1.5 V, and AGP 2.0 'universal' connectors which could support either voltage were released. AGP version 3.0, released in 2002, doubled the speed of AGP 2.0 with a new AGP 8x mode.
Introduction to the AGP bus
The AGP bus (short for Accelerated Graphics Port) was released in May 1997 for Slot One chipsets, then was later released for Super 7 chips in order to manage graphical data flow, which had grown to large to be handled by a PCI bus. The AGP bus is directly linked to the processor's FSB (Front Side Bus) and uses the same frequency, for increased bandwidth.
The AGP interface was developed specifically to connect with the video card, by opening a direct memory access (DMA) channel to the graphics board, bypassing the input-output controller. Cards which employ this graphics bus theoretically require less on-board memory; because they can directly access graphical data (such as textures) stored in central memory, their cost is hypothetically lower.
Version 1.0 of the AGP bus, which used 3.3 V of power, had a 1X mode that could send 8 bytes every two cycles, and a 2x mode for transferring 8 bytes per cycle.
In 1998, AGP version 2.0 added AGP 4X, which could send 16 bytes per cycle. Version 2.0 of AGP was powered by 1.5 V, and AGP 2.0 'universal' connectors which could support either voltage were released.
AGP version 3.0, released in 2002, doubled the speed of AGP 2.0 with a new AGP 8x mode.
Characteristics of AGP
The AGP 1X port operates at 66 MHz, as opposed to 33 MHz for a PCI bus, giving it a top speed of 264 MB/s (vs. 132 MB/s, shared between all the cards, for PCI). This gives AGP better performance, especially when displaying complicated 3D scenes.
When AGP 4X was released, its speed went up to 1 GB/s. This generation of AGP used 25 W of power. The next generation was named AGP Pro and used 50W.
AGP Pro 8x offers speeds of 2 GB/s.
The transfer speeds for the various AGP standards are:
- AGP 1X: 66.66 MHz x 1(coef.) x 32 bits /8 = 266.67 MB/s
- AGP 2X: 66.66 MHz x 2(coef.) x 32 bits /8 = 533.33 MB/s
- AGP 4X: 66.66 MHz x 4(coef.) x 32 bits /8 = 1.06 GB/s
- AGP 8X: 66.66 MHz x 8(coef.) x 32 bits /8 = 2.11 GB/s
It should be noted that each of these AGP standards is backwards-compatible, meaning that AGP 4X or AGP 2X cards can be inserted into an AGP 8X slot.
AGP Connectors
Recent motherboards are built with a general AGP connector which can be identified by its brown color. There are three types of connectors:
- AGP 1.5 volt connector:
- AGP 3.3 volt connector:
- Universal AGP connector:
Summary
Here is a table summarising the technical specifications for each version and mode of AGP:| AGP | Voltage | Mode |
|---|---|---|
| AGP 1.0 | 3.3 V | 1x, 2x |
| AGP 2.0 | 1.5 V | 1x, 2x, 4x |
| AGP 2.0 universal | 1.5 V, 3.3 V | 1x, 2x, 4x |
| AGP 3.0 | 1.5 V | 4x, 8x |
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Agp Universal Slot Machine
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Agp Universal Slot Machines
As fast and wide as the PCI bus was, there was one task that threatened to consume all its bandwidth: displaying graphics. Early in the era of the ISA bus, monitors were driven by simple Monochrome Display adapter (MDA) and Colour Graphics Array (CGA) cards. A CGA graphics display could show four colours (two bits of data) at 320 by 200 pixels screen resolution at 60Hz, which required 128,000 bits of data per screen, or just over 937 KBps. An XGA image at a 16-bit colour depth requires 1.5MB of data for every image, and at a vertical refresh rate of 75Hz, this amount of data is required 75 times each second. Thanks to modern graphics adapters, not all of this data has to be transferred across the expansion bus, but 3D imaging technology created new problems.
3D graphics have made it possible to model both fantastic and realistic worlds on-screen in enormous detail. Texture mapping and object hiding require huge amounts of data, and the graphics adapter needs to have fast access to this data to avoid the
AGP operates at the speed of the processor bus, now known as the frontside bus. At a clock rate of 66MHz this is double the PCI clock speed and means that the peak base throughput is 264 MBps.
For graphics cards specifically designed to support it, AGP allows data to be sent during both the up and down clock cycle, doubling the clock rate to 133MHz and peak transfer to 528 MBps. This is known as 2x. To improve the length of time that AGP can maintain this peak transfer, the bus supports pipelining, which is another improvement over PCI. A pipelining 2x graphics card will be able to sustain throughput at 80% of the peak. AGP also supports queuing of up to 32 commands via a process called Sideband Addressing (SBA), the commands being sent while data is being received. This allows the bus to sustain peak performance for 95% of the time, according to Intel.
AGP’s four-fold bandwidth improvement and graphics-only nature ensures that large transfers of 3D graphics data don’t slow up the action on screen; nor will graphics data transfers be interrupted by other PCI devices. Being primarily intended to boost 3D performance, AGP also provides other improvements that are specifically aimed at this function.
With its increased access speed to system memory over the PCI bus, AGP can use system memory as if it’s actually on the graphics card. This is called Direct Memory Execute (DIME). A device called a Graphics Aperture Remapping Table (GART) handles the RAM addresses so that they can be distributed in small chunks throughout system memory rather than hijacking one large section, and presents them to a DIME-enabled graphics card as if they’re part of on-board memory. The main use for DIME is to allow much larger textures to be used because the graphics card can have a much larger memory space in which to load the DRDRAM) in the second half of 1999. AGP 2.0 was supported by chipsets launched early in 1999 to provide support for Intel’s Katmai processor.
AGP Pro is a physical specification aimed at satisfying the needs of high-end graphics card manufacturers, who are currently limited by the maximum electrical power that can be drawn by an AGP card (about 25W). AGP Pro caters for cards that draw up to 100W, and will use a slightly longer AGP slot that will also take current AGP cards.