Computersight -

A motherboard is one of the most complex pieces of hardware. Since it is built to accept connections, a certain version can only accept a certain standard of components.

Slots

Slots are where you insert any add on components into the motherboard. Slots come in various sizes, shapes and specifications for different requirements.

ISA slot

These slots are very old. They were introduced by IBM back in 1981. Now, they have been completely phased out. ISA stands for Industry Standard Architecture. It was used for video, audio and network cards. They had two versions, 8-bit and 16-bit, running at 4.77MHz and 6MHz – 8MHz respectively. You can still find these slots on motherboards about six years ago, though you’ll be hard pushed to find a suitable card for this standard. They can be identified by their black colour and length.

PCI slot

These slots are fairly recent technology, though they are getting phased out after the introduction of the new PCI Express slot. They were introduced by Intel in 1993. They offered a bandwidth of 32 or 64 bits, with a clocked speed of 33.33MHz and a throughput of 133MBps. This is a huge improvement over ISA and this is a major contribution to the fact that PCI is a famous standard among sound cards and internal modems today.

AGP slot

Unfortunately the PCI slot did not give much enhancement to graphics as it did to the sound cards and modems. So, around 1997, Intel introduced the AGP standard to used almost only for graphics cards. AGP stands for Accelerated Graphics Port. The AGP 8x standard boasts of a 66MHz clock, but since the 8x interface strobes 8 times per clock cycle, the interface delivered an impressive 533MHz while the data throughput amounted to about 2133MBps or 2GBps. This scorching speed, though theoretical, is a vast improvement over PCI.

PCI Express

However, AGP could not keep up with the increasing demands of the graphics card industry and it finally gave way to PCI Express. This standard was introduced by Intel in 2004 and is currently the ruler in the land of the slots. PCI-E 16x is used for graphics cards while the toned-down PCI-E 2x is used for sound cards. Unlike previous slots, the transmission mode is serial, and thus it can transmit greater amounts of data per lane. The latest version of this standard, PCI-E 3.0, has a transmission rate of 1.0GBps per lane.

Processor Slots

Some years ago, processors were available in two versions; You could opt for the slot processor, to be inserted into a slot just like graphics cards, or for a socket processor, like the present day processors. These slots are brown and completely isolated from the other slots. These slot processors have been phased out for socket processors, due to higher speed requirements.

These are the slots currently considered while manufacturing motherboards today.

The Future

PCI-E version 3 has been released bringing exciting features like better throughput and greater bandwidth. The next version of PCI-E is already on research and it promises a better experience with graphics cards.