When it comes to the world of consumer-grade electronics, absolutely nothing stands still. What was considered cutting-edge a mere decade ago is today all but ancient history, with tech components, peripherals, and standards evolving exponentially on seemingly a yearly basis.
PS/2
No, not the video game console
If you're old enough to remember the pre-optical sensor days of computer mice with trackballs on their undersides, then you'll probably also remember the PS/2 port. Available in both purple and green flavors for keyboards and mice, respectively, these 6-pin connectors were first introduced by IBM in its 1987 Personal System/2 series of desktop computers. Over time, these dual ports grew into a full-blown PC standard for connecting key and cursor input devices.
Today, USB-A mice and Bluetooth wireless mice have made the PS/2 standard all but obsolete, though you'll occasionally find single purple and green combo ports on some desktop computers. Fans of PS/2 cite its technical responsiveness when it comes to tracking user input, though this comes at the expense of not being hot swappable (you'll need to turn off or restart your computer if you plan on plugging in or unplugging PS/2 mice and keyboards).
FireWire
A popular serial bus standard found on retro Macs
FireWire was once a relatively popular I/O port in the PC space, serving as an alternative to the USB standard. The term itself is actually an Apple-owned trademark for the IEEE 1394 serial bus interface (retroactively referred to as FireWire 400), which was first designed in the mid 80s before being standardized in 1995. Over time, various improvements were made to the specification to improve on bandwidth and other technical underpinnings, including IEEE 1394a in 2000, IEEE 1394b (FireWire 800) in 2002, and IEEE 1394c (FireWire S800T) in 2006.
Over time, USB overtook FireWire as the de facto serial bus standard, and today you'll be hard-pressed to find any peripherals that make use of the IEEE specification. Apple, for its part, officially removed all support for the FireWire standard in the recently-released macOS 26 Tahoe, marking the end of an era.
HDD
Spinning hard drives were once ubiquitous
Hard Disk Drives, known as HDDs for short, rely on a spinning magnetic platter and an actuating arm head to read and write data. External HDDs are still a popular on-the-go storage solution due to their relative market affordability, but the days of built-in personal computer hard drives has quickly become a thing of the past.
Simply put, modern flash memory and solid state drives (SSDs) are far snappier than traditional HDDs, making for quicker loading and boot times when navigating through contemporary operating systems. As an added bonus, flash storage is less susceptible to being physically damaged than traditional spinning platters, which is particularly important in today's mobile-first computing environment.
30-pin connector
The original iDevice docking port
Apple's earliest iPod models actually shipped with FireWire ports to facilitate data transfer with the Mac, but by the time of the third generation model in 2003, the company introduced the proprietary 30-pin dock connector. Had the iPod been the extent of the 30-pin's importance in the tech scene, it'd hardly make for a memorable and iconic port standard, but, as history would have it, Apple continued to embrace the standard well into the iPhone and iPad era.
Eventually, Apple switched to the much smaller (and reversible) Lightning connector across its iPod, iPhone, and iPad lineups in 2012, which itself was slowly superseded by USB Type-C on modern iDevices. The classic 30-pin connector was admittedly bulky and cumbersome to operate, but it stands out as one of the most well-known proprietary ports to ever hit the consumer tech market.
Floppy disk
Known more commonly today as the save icon
Before we had SD cards and USB flash drives, floppy disks (also known as diskettes) were all the rage. The original IBM-designed floppy standard from 1971 measured in at 8-inches in diameter, followed by the Shugart Associates-designed 5 and 1/4-inch variant in 1976, and the Sony-designed 3 and 1/2-inch version in 1981. These smaller 3 and 1/2-inch floppy disks in particular became the standard for externally storing files and data in the 1990s and even well into the 2000s.
Floppy drives are deceptively non-floppy on the outside, owing to their hard plastic exterior shell. On the inside, however, they featured a malleable magnetic disk-shaped tape that did much of the heavy lifting. A standard 3 and 1/2-inch floppy can hold approximately 1.44 MB of data, and so it's no surprise that the technology was replaced the moment higher-capacity options became available and affordable for PC users.
VGA
A classic analog video port
These days, HDMI, DisplayPort, and USB-C rule the external monitor roost. Back in 1987, however, it was IBM's all-new Video Graphics Array (VGA) video output standard that captured the public's attention. This 15-pin port became downright ubiquitous across the entire PC ecosystem, to the point where it's still commonly found in use in certain enterprise, government, and medical contexts.
While USB-C to VGA adapters are readily available for purchase, you probably won't want to connect a dusty old VGA monitor to your modern-day computer. The standard, which is analog and not digital, is capable of only up to about 2048×1536 resolution, and the I/O port itself is bulky with delicate pins and a somewhat frustrating lock mechanism to boot.
DVI
A video port with digital capabilities
DVI, which stands for Digital Virtual Interface, is another legacy video connector type commonly found on older computer monitors. Designed by the Digital Display Working Group (DDWG) and released to the public in 1999, DVI is unique in that it features both analog and digital transmission signals within the same connector type. A number of connector variants exist, each with their own pin arrangements and corresponding capabilities. These include DVI-I, DVI-D, and DVI-A, which can then be further broken down by their Single Link and Dual Link formats.
As a successor to VGA, DVI was certainly a technological step-up, but it fell out of fashion in the late 2000s due to increased competition from other more capable digital monitor standards like HDMI and DisplayPort. As with its VGA predecessor, DVI lacks the all-important ability to carry audio simultaneously alongside a video signal, and so it inconveniently requires the use of a separate cable to route audio to and from your PC.
Optical disc
CD and DVD drives were once a PC staple
For a brief period of time, optical media represented the pinnacle of digital storage. Compact Discs (CDs) were introduced to market by Philips and Sony in 1982, capable of holding approximately 700 MB of data on a single disc. Later, Digital Video Disc (DVD) was developed and released by Sony, Philips, Panasonic, and Toshiba in 1996, upgrading the storage capabilities to anywhere between 4.7GB and 17.08 GB depending on the number of layers and sides being utilized. Finally, Sony spearheaded the Blu-ray era in 2006, which once again upped the storage capacity to between 25 GB and 128 GB depending on the variant in question.
While CDs are primarily used as a medium for distributing music albums and DVDs and Blu-rays are typically reserved for storing motion pictures, personal computers were soon sprouting optical drives of their own as a means to store portable data much more densely than, say, a floppy diskette. Of course, with the miniaturization of technology and the portability factor of modern laptops and tablet PCs, optical drives have nearly gone extinct within the realm of computing, ending the era of personal mixtape burning once and for all.
IR blaster & remote
From back in the media center PC days
In the 2000s, there was a new trend within the tech space that involved using computers as home theater or media center PCs. As a pseudo-rival to TV set-top boxes and to video game consoles of the time, PCs offered a flexible multimedia experience that made for a genuinely compelling living room setup option. Many desktop PCs of the era shipped with dedicated IR blaster modules that could be plugged in via USB, in addition to IR-powered remote controls for more suitable interfacing while lying on the couch.
Microsoft built a dedicated Windows Media Center experience into its Windows XP, Vista, 7, and 8 operating systems, eventually discontinuing the home theater software as of Windows 10 in 2015. Today, media center PCs are a relic of the distant past, replaced by dedicated set-top boxes, home video game consoles, Blu-ray players, and streaming sticks.
Centronics connector
A parallel port used for old-school printers
Before USB came in and universalized PC connectivity, a variety of parallel port standards competed with one another across the computing industry. One of the most well-known and long-lasting parallel interface connectors to hit personal computers was an unassuming dual-row port with a varying number of pins, which went on to be commonly used for connecting printers to desktops. Over time, the port became known colloquially as the Centronics connector, owing to its adoption by the Centronics Data Computer Corporation across its line of home printer devices.
Thankfully, with the advent of USB and later with the release of wireless printers, the comically large and non-flexible Centronics connector died off across all but the most legacy-oriented desktop tower PCs, and today it's one of the more obscure ports to have previously been considered a de facto market standard.