Buses: Universal Serial Bus (USB) and Accelerated Graphics Port (AGP)

New technologies pop up every few weeks to solve our everyday problems, and make life easier. But in the long run it proves to confuse most of the users.

Today we'll speak about Universal Serial Bus (USB). Generally everyone knows the term but particularly a few of us know what it is about.

What is USB bus about?

USB is a port (entry) situated mainly on the back of your PC. It allows to plug in multiple devices provided with a USB connectors. You can plug in the following devices: keyboards, scanners, digital cameras, flash drives, mice, etc.

What's a USB hub?

This a part of USB feature. You can connect one end of a cable to the USB port of your PC and another end to a USB hub. This enables you to connect four or more devices right into it.

There are two main types of USB hubs: powered and unpowered. There are a lot of devices that work fine with unpowered hubs, still some of them need power. Which is better? Powered for sure!

Speed, Conflicts

It is already an axiom the fact that the more devices are added to a system, the slower it will work. This will certainly involve further conflicts and crashes. USB addresses two of the major problems with PCs: speed and conflicts. Plug-and-play capabilities make it easier to avoid system conflicts, but this doesn't mean they eliminate them.

The USB technology is capable of handling a wide range of devices without slowing down the system. Theoretically, you can add up to 255 external devices! Each of them is detected upon connecting or removing without rebooting your PC. USB can automatically determine host resources, driver software and bus bandwidth needed by each peripheral.

The bus carries 5V power which means you won't need power converters for every single device. And even more, USB is able to define standard connectors and sockets for all peripherals to use!

Accelerated Graphics Port (AGP)

First versions (1x and 2x speeds) of Accelerated Graphics Port (AGP) were released by Intel in 1997, as adjuncts to the PCI (Peripheral Components Interconnect) bus. AGP was primary designed for point-to-point graphics components. It significantly improves the performance of 3D graphics and other visually intensive applications.

PCI bus and AGP bus are physically separated from one another and use separate connectors. AGP adds new features for graphics accelerators. It manages faster data transfer rates and a dedicated pipelined access to main memory.

AGP deals with features such as alpha-blending, texture-mapping, Z-buffering, etc. In other words it means that your digital video will run faster, games will look better, and animations will be even more realistic.

Currently there are available following versions of AGP:
AGP 1x - A 32-bit channel operating at 66 MHz resulting in a maximum data rate of 266 MB/s, doubled from the 133 MB/s transfer rate of PCI bus 33 MHz / 32-bit; 3.3 V signaling.
AGP 2x - A 32-bit channel operating at 66 MHz double pumped to an effective 133 MHz resulting in a maximum data rate of 533 MB/s; 3.3 V signaling;
AGP 4x - A 32-bit channel operating at 66 MHz quad pumped to an effective 266 MHz resulting in a maximum data rate of 1066 MB/s (1 GB/s); 1.5 V signaling;
AGP 8x - A 32-bit channel operating at 66 MHz, strobing eight times per clock, delivering an effective 533 MHz maximum data rate of 2133 MB/s (2 GB/s); 0.8 V signaling.