#‎introduction_to_hardware_continue‬

 

Motherboard Slots

To add more functionality to a computer, cards such as network or video cards can be added. Sometimes these functions are built into the motherboard. There are several types of expansion slots:

The PCI (Peripheral Component Interconnect) The PCI bus is common in modern PCs, where it has displaced ISA as the standard expansion bus, but it also appears in many other computer types.

PCI 2 33.33 MHz clock with synchronous transfers peak transfer rate of 133 MB per second for 32-bit bus
PCI 2.2 allows for 66 MHz signalling (requires 3.3 volt signalling) (peak transfer rate of 503 MB/s) PCI 2.3 permitted use of 3.3 volt and universal keying, but did not support 5 volt keyed add in cards.
PCI 3.0 is the final official standard of the bus, completely removing 5 volt support.

ISA/EISA; Industry Standard Architecture and Extended Industry Standard Architecture An older type of bus connector. Considered obsolete

PCI Express, PCIe, or PCI-E is an implementation of the PCI computer bus that uses existing PCI programming concepts, but bases it on a completely different and much faster serial physical-layer communications protocol. PCIe transfers data at 250 MB/s (238 MiB/s), per channel to a maximum of 16 channels, a total combined transfer rate of 4GB/s (3.7 GiB/s). Almost all of the high end graphics cards pbeing released today use PCI Express. NVIDIA uses the high-speed data transfer of PCIe for its newly developed Scalable Link Interface (SLI) technology, which allows two graphics cards of the same chipset and model number to be run at the same time, allowing increased performance.

The Accelerated Graphics Port (also called Advanced Graphics Port) is a high-speed point-to-point channel for attaching a graphics card to a computer’s motherboard, primarily to assist in the acceleration of 3D computer graphics. Some motherboards have been built with multiple independent 

AGP slots. AGP is slowly being phased out in favour of PCI Express.

AGP 1x, using a 32-bit channel operating at 66 MHz resulting in a maximum data rate of 266 megabytes per second (MB/s), doubled from the 133 MB/s transfer rate of PCI bus 33 MHz / 32-bit; 3.3 V signaling.
 

AGP 2x, using 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; signaling voltages the same as AGP 1x;
 

AGP 4x, using 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, using a 32-bit channel operating at 66 MHz, strobing eight times per clock, delivering an effective 533 MHz resulting in a maximum data rate of 2133 MB/s (2 GB/s); 0.8 V signaling.

Peripheral Connections
There are a number of ports on the motherboard for the connection of additional devices:.

Serial ports connected the computer to devices such as terminals or modems. Mice, keyboards, and other peripheral devices also connected in this way.

Parallel ports are most often used to communicate with peripheral devices. The most common kind of parallel port is a printer port, such as a Centronics connector based port which transfers eight bits at a time. Disk drives are also connected via special parallel ports, such as those used by the SCSI and 

ATA
technlogies. However, when people refer to a parallel port, they are usually referring to a printer port, either on a printer or a PC.

A USB system has an asymmetric design, consisting of a host controller and multiple daisy-chained devices. Additional USB hubs may be included in the chain, allowing branching into a tree structure, subject to a limit of 5 levels of branching per controller. No more than 127 devices, including the bus devices, may be connected to a single host controller. Modern computers often have several host controllers, allowing a very large number of USB devices to be connected. USB cables do not need to be terminated.

USB supports three data rates.

A Low Speed rate of 1.5 Mbit/s (183 KiB/s) that is mostly used for Human Interface Devices (HID) such as keyboards, mice, and joysticks.
 

A Full Speed rate of 12 Mbit/s (1.5 MiB/s). Full Speed was the fastest rate before the USB 2.0 specification and many devices fall back to Full Speed. Full Speed devices divide the USB bandwidth between them in a first-come first-served basis and it is not uncommon to run out of bandwidth with several isochronous devices. All USB Hubs support Full Speed.
A Hi-Speed rate of 480 Mbit/s (57 MiB/s).

‪#‎Diagram_showing_motherboard_slot‬