Difference Between Expansion Slot And Port

When you decide to expand your PC with a new device, you need to understand the expansion slots on your PC’s motherboard so you can determine what type of new device to buy. There are a bunch of different expansion slot standards and variations.

The two most common slots available on today’s PCs are PCI and PCI-Express:

In computing, the expansion card, expansion board, adapter card or accessory card is a printed circuit board that can be inserted into an electrical connector, or expansion slot, on a computer motherboard, backplane or riser card to add functionality to a computer system via the expansion bus. An expansion bus is a computer bus which moves information between the internal hardware of a. Jan 05, 2018  For example, all desktop computer expansion cards have a connector that allows them to connect in a slot on the motherboard. When referring to cables, the connector is the end of the cable that connects into a port. For example, the end of a USB cable has.

Expansion ports are different types of connection ports on a laptop that allow various kinds of external devices to be connected to the machine. There are numerous types of connectivity ports from the most basic USB till the latest Express card slot. So, let’s begin to explore all of them without further ado. System Bus vs Expansion Bus. Summary: Difference Between System Bus and Expansion Bus is that system bus, also called the front side bus (FSB), is part of the motherboard and connects the processor to main memory. While an expansion bus allows the processor to communicate with peripherals. Some peripherals outside the system unit connect to a port on an adapter card, which is inserted in an.


Difference Between Ports And Slots

PCI: The Peripheral Component Interconnect type of slot is the most popular and widely available expansion slot on today’s PCs. It’s normally colored white, though often beige is used. There are 32-bit and 64-bit PCI expansion slots.

PCIExpress: The latest rendition of the PCI standard is PCI-Express. PCI-Express slots are generally colored black or dark gray or sometimes even yellow. They also feature a variety of sizes.

Older expansion standards include

PCI-X: The PCI Extended standard was developed to improve on PCI, but as a standard PCI-Express superseded it. Some older PCs may still feature the PCI-X slot, which looks like a standard PCI slot but is considerably longer.

Be careful not to confuse PCI-X with PCI-Express! They’re different standards, different slots, and different expansion card types.

AGP: The Accelerated Graphics Port slot was designed specifically to handle high-end graphics adapters. It may still be found on older PCs, but today’s systems use PCI-Express expansion slots to handle high-end graphics adapters. AGP slots were often colored maroon and had a hinged hook on one end to help anchor the AGP card.

ISA: The original expansion slot for the PC family was ISA, which simply stood for Industry Standard Architecture (because the expansion slot lacked an official and suitably technical-sounding name). It had two varieties: 16-bit and a longer 16-bit version. An older Windows XP system may still sport an ISA slot, but few (if any) relevant ISA expansion cards are available today.

Expansion Port Vs Expansion Slot

Sadly, without opening the case, there’s no way to determine what type of slots are present on your PC’s motherboard, let alone whether the slots are available (or empty). The only way to know for certain is to open the case and have a look.

  • When the PC’s motherboard features a variety of slots, and you have a choice, choose a PCI-Express expansion card first.

  • Expansion slots are keyed: The edge connector on the expansion card cannot be plugged in backward. Of course, most expansion cards feature a rear slot mount, which means that you have to be determined to plug an expansion card in backward in the first place!

  • You can look on the back of your PC and examine the slot covers to determine whether a slot is empty. A blank slot cover, however, may not indicate that an expansion slot is available, because some expansion cards may not use the slot cover. Also, some expansion cards are double-wide and may render useless any empty expansion slots next to them. Online slots real money ohio.

  • Even though the expansion slots are all standardized, expansion cards come in different lengths. You can find full-length cards, half-size cards, and others. Smaller PC consoles may have room for only smaller expansion cards, or perhaps some expansion slots are limited to hosting only shorter expansion cards. Knowing this type of information before you buy an expansion card will prove to be a boon to your self-esteem.

  • PCI-X also featured two sets of voltages for expansion cards: 5 volts and 3.3 volts. Special notches in the expansion cards prevented the wrong slot from being used, but the differing voltages were still an issue for choosing the proper PCI-X expansion card.

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CNR slot

Expansion Slots

Communications and networking riser (CNR) is a slot found on certain PC motherboards and used for specialized networking, audio, and telephony equipment. A motherboard manufacturer can choose to provide audio, networking, or modem functionality in any combination on a CNR card. CNR slots were once commonly found on Pentium 4-class motherboards, but have since been phased out in favor of on-board or embedded components.


Physically, a CNR slot has two rows of 30 pins, with two possible pin configurations: Type A and Type B, each with different pin assignments. CNR Type A uses 8-pin PHY interface, while Type B uses 17-pin media-independent interface (MII) bus LAN interface. Both types carry USB and AC'97 signals.

As with AMR, CNR had the cost savings potential for manufacturers by removing analog I/O components from the motherboard. This allowed the manufacturer to only certify with the US Federal Communications Commission (FCC) for the CNR card, and not the entire motherboard. This resulted in a quicker production-to-market time for new motherboards, and allowed mass-production of CNR cards to be used on multiple motherboards.

Expansion Slots Types

The ACR slot was a competing specification developed by a group of third-party vendors. Its principal advantage over CNR was the backwards-compatible slot layout which allowed it to use both AMR and ACR cards. The same group also developed a physically smaller version, the MDC.


Modem for CNR slot.

Intel developed the CNR slot to replace its own audio/modem riser (AMR) technology, drawing on two distinct advantages over the AMR slot it replaced; CNR was both capable of being either software based (CPU-controlled) or hardware accelerated (dedicated ASIC), and was plug-and-play compatible. On some motherboards, a CNR slot replaced the last PCI slot, but most motherboard manufacturers engineered boards which allow the CNR and last PCI slot to share the same space.

With the integration of components such as ethernet and audio into the motherboard, the CNR is obsolete, and is not found on PC motherboards anymore.

See also[edit]

  • Advanced Communications Riser (ACR)
  • Audio/modem riser (AMR)
  • Mobile daughter card (MDC)

External links[edit]

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