One of the characteristics that sets the PC apart from other platforms is its scalability. Thanks to its entry and exit ports. Which allows you to connect all kinds of components and peripherals.
General characteristics of inlet and outlet ports
I / O ports are communication ports, responsible for transmitting a series of data between two ends, all of them have the following characteristics:
- A clock: This signal indicates how often a data transfer is performed.
- Data pins: The pins that carry information from side to side, there are the receive pins, the send pins, and the full duplex that allows data to go one way or the other. If there are multiple data pins on the port interface, we will say it is parallel port, if there are few pins, we will say it is serial port.
It should be noted that just because a port is serial does not at all mean that it is slower, as the amount of data sent and / or received will depend on their clock speed. I / O interfaces as well as the rest of the logic of the processors have evolved over time and what, for example, was previously only possible with large parallel ports, has reached the point that has become possible. with serial ports.
Input and output ports in use today
These ports are what you can find on PCs and motherboards sold today.
USB input and output ports
USB ports are the absolute standard for input and output ports, as they are used by a multitude of devices. Its origin, however, lies outside the PC, since it is a version adapted to the PC and updated on the SIO port of 8-bit Atari computers. The SIO port has avoided having to put an entire computer in its floppy drives as has happened in other 8-bit computers.
The USB standard appeared at the end of the 90s with the aim of replacing various ports on the PC, such as the Centronics or LPT1 port, the COM port and the PS / 2 ports. A goal that took years to achieve due to the proliferation of devices with these interfaces. Its first version had a transfer speed of only 11 Mbps, its version 2.0 improved to 480 Mbps and it also became an ideal port for video transmission, thus removing the IEEE-1394 or FireWire. As for its version 3.0, it allows data transfer at the speed of a SATA port.
USB comes in many forms, but the most recent is USB-C which not only allows fast charging of peripherals and even entire computers. But also work as a DisplayPort. Seeing its history, it is clear that the term Universal has more than deserved it.
HDMI video output ports
The HDMI port is the absolute video standard in televisions, it is an advanced version of the already abandoned DVI port but including the possibility of transmitting sound and playing content in high definition with rights protection systems. ‘author. HDCP. It first emerged when component cable was found not to provide enough bandwidth for Full HD, and Blu-ray and streaming content required an anti-piracy control method.
Today, it has evolved in terms of capabilities and bandwidth, enabling transmission of 8K video and refresh rates beyond conventional 60Hz.
DisplayPort video output ports
The other video output port is DisplayPort, but while HDMI is a standard for TV manufacturers, DisplayPort is geared more towards the computer market, so this port is rarely found on TVs. Like HDMI, it has had several versions, but it is more intended for use in a computer, due to such things as the fact that it supports a greater number of resolutions in its standard compared to HDMI and is designed for the use of multiple displays.
RJ45 or Ethernet ports
The Ethernet port of a lifetime, which allows us to connect at high speed with our PC to the network, which cannot be reached by any type of wireless standard. Its permanence is due to its evolution where if years ago we spoke of 100 Mbps connections, today we already have 10,000 Mbps or 10 Gbps interfaces.
3.5mm mini jack and TRS connectors
This is the port for connecting speakers and microphone par excellence. The connector has 2 variations, the first one supports mini-jack connections with 2 rings in which each ring corresponds to a stereo channel, a third ring means the microphone can be used. Although there are systems that separate input and output in two different interfaces.
A variation of this type of connection is the TRS connectors, which allow multiple speakers to be connected in a positional system. Of course, with the limitations of bandwidth and sound quality
S / PDIF ports for digital audio
When DVD became popular so did DOLBY Digital, which was the first truly positional system and therefore required much higher bandwidth. The solution? The port in S / PDIF or SONY / Phillips digital interface format. That transmits audio in digital format through a coaxial cable in a single port.
Advanced multi-speaker systems such as 7.1 use these types of connectors. Which are much better than TRS. Not only so you don’t need so many cables, but to deliver superior sound quality with higher bandwidth.
PCI Express Ports
PCI Express slots are where we connect our graphics cards and M.2 NVMe drives today, as well as other though less used peripherals that require this port. Designed as the successor to AGP and classic PCI, it is a standard that appeared in the mid-2000s and has evolved until now, where version 4.0 is already on the market, version 5.0 is on the launch pad and the 6.0 has already finished its design. Each generation doubles the bandwidth for communication,
Its peculiarity compared to other I / O ports is that it inherits from AGP the ability to directly access the system RAM. Of course, with the corresponding control mechanisms. This is essential for CPU-GPU communication and for being able to copy data more efficiently from an NVMe SSD.
Input and output ports that ceased to exist
These ports are barely visible on the PC, being replaced by ports that do the same task but with higher performance, better consumption, or both. Although we can see them used in some motherboards today.
RS-232 or DB9 port
This port was used to communicate hardware in the age of minicomputers. Especially the terminals. It was adopted by the PC in the early years being the quintessential I / O port for peripherals such as keyboards, mice, modems and a long etc.
First it was replaced in use by the PS / 2 port in terms of mice and keyboards, high speed modems began to use more advanced ports such as ISA and gradually it s ‘is terminated in disuse until its removal by USB. When this happened, it was one of the most unnecessary parts of a PC.
The famous printer port, a parallel port that first appeared on IBM MDA graphics cards and later became part of the motherboard. It was taken off the market as soon as the USB port first appeared, and it became so slow that it despaired. It’s a 36-pin parallel port that was originally designed for printers and scanners.
Over time, the Centronics port was replaced by the parallel port or the DE9 port, which is a parallel version of the DB9 port, so it is based on the RS-232 standard. As the two are known as printer ports, they were often confused, which is why we’ve grouped them together in the same section.
The VGA port was the go-to standard for PC CRT screens, and it managed to live for almost 20 years, but it was found to be unable to display good image quality on an LCD screen, so it has was quickly replaced by standards such as DVI. HDMI and DisplayPort.
The VGA port is related to CRT monitors, but has also been used in projectors. Its disappearance is due to the increase in the use of digital video, much better understood with LCD panels, which, by taking up less space, ended up replacing televisions and monitors with analog signals.
The DVI port was an attempt by VESA before DisplayPort to launch a successor to VGA. In reality, HDMI derives from this port, with the difference that DVI does not support HDCP content, it does not transmit audio and it has not evolved with the evolution of HDMI. You can see it on televisions and monitors of the second half of the 2000s.
The DVI standard had 3 different types of connections, DVI-I could transmit signals in analog and digital, DVI-D only in digital and DVI-A only in analog. Each with a different pin configuration. These differences not found in HDMI or DisplayPort were one of the reasons DVI did not have a longer duration.