If you've ever opened the back of an older desktop computer, you've seen the purple and green round ports near the bottom — sometimes labeled with tiny keyboard and mouse icons. These are PS/2 ports, and despite USB having replaced them on virtually every new device since the early 2000s, PS/2 connections still exist on motherboards in 2026.
Here's what those purple and green ports are for and why they haven't disappeared yet.
What is PS/2?
PS/2 is an IBM specification from 1987 (yes, 1987) for connecting keyboards and mice to computers. The name comes from IBM's "Personal System/2" computer line where the standard debuted.
The PS/2 connector is a 6-pin Mini-DIN — a small round connector with 6 metal pins arranged inside, plus a plastic alignment key that ensures the connector goes in the right way. The connector locks lightly into place when fully inserted.
Two PS/2 ports were standard on PC motherboards from 1987 until USB took over in the early 2000s. The two ports are functionally identical electrically, but BIOS firmware historically expected the keyboard to be in one port and the mouse in the other.
The color coding
Around 1999, the PC 99 specification introduced standardized colors for PC ports so users could easily identify which cable goes where without reading labels.
Purple PS/2 port — Keyboard Green PS/2 port — Mouse
Most computers from 1999-2010 used these colors. Cables and connectors also followed the convention — purple boot for keyboard cables, green for mouse cables.
The color coding helped reduce a common user frustration: plugging the keyboard into the mouse port (or vice versa) wouldn't work because the BIOS expected specific devices on specific ports. Newer PS/2 implementations are smart enough to detect what's plugged in regardless of port, but the colors stuck around as a convention.
PS/2 vs USB
In nearly every way, USB has won. USB keyboards and mice are hot-swappable, work on any USB port, are universally compatible, and support modern features like multi-touch and programmable function buttons.
Where PS/2 still has technical advantages:
Hardware-level interrupts — PS/2 keyboards and mice generate hardware interrupts when keys are pressed. The CPU processes these immediately. USB devices are polled by the operating system at fixed intervals. For most users this is invisible, but in a few specific scenarios, PS/2 has measurably lower latency.
Pre-boot environments — In some BIOS recovery scenarios, secure boot processes, or specific OS installations, PS/2 keyboards work when USB keyboards don't. Sysadmins working with servers and recovery procedures sometimes prefer PS/2 for this reliability.
N-key rollover — Standard PS/2 supports unlimited simultaneous keypresses (N-key rollover). USB keyboards typically support 6-key rollover by default, though gaming keyboards work around this with custom drivers.
Security applications — Some high-security environments prefer PS/2 because it can't be silently bridged to network devices like USB can (BadUSB attacks, etc.).
Where you'll still find PS/2 in 2026
Motherboard ports — Many higher-end motherboards from ASUS, MSI, ASRock, and Gigabyte still include a single PS/2 port (often combo purple/green for either keyboard or mouse). Server motherboards almost always have PS/2.
KVM switches — Many enterprise KVM switches still support PS/2 in addition to USB, especially in data centers with mixed equipment ages.
Industrial computers — Industrial PCs, point-of-sale systems, and embedded computers often have PS/2 for reliability and compatibility with legacy equipment.
Server BMC/IPMI consoles — Server out-of-band management still sometimes uses PS/2 for keyboard input on console KVM connections.
Specialty input devices — Some niche industrial keypads, medical equipment input devices, and specialty hardware still use PS/2 for the reasons mentioned above.
PS/2 to USB adapters
If you have a PS/2 keyboard or mouse but only USB ports on your computer, you have two options:
Active adapters — Contain a small chip that converts between USB and PS/2 protocols. These work reliably with most PS/2 devices. Look for "Active USB to PS/2" adapters, typically $10-15.
Passive adapters — Just rewires the pins. These ONLY work with PS/2 devices that were specifically designed to also speak USB protocol (some "USB or PS/2" keyboards/mice). If your PS/2 device is purely PS/2, a passive adapter won't work. Passive adapters are cheaper ($2-5) but often disappoint buyers who don't realize the distinction.
Most modern peripherals labeled "PS/2 or USB" came with both a PS/2 connector and a small adapter that's actually passive — the device itself was dual-mode.
Going the other direction: USB to PS/2
Converting a USB keyboard or mouse to work in a PS/2 port is harder because the device has to actively translate USB protocol to PS/2. Powered USB-to-PS/2 converters exist but are less common and more expensive than the other direction.
Buying PS/2 cables and adapters
For most users, the only PS/2 product worth buying in 2026 is a USB-to-PS/2 active adapter for older keyboards or mice you want to keep using. These work with mechanical keyboards from the 1990s, certain industrial input devices, and specialty hardware.
If you maintain older industrial or server equipment, you might also need PS/2 extension cables (male-to-female 6-pin Mini-DIN) for KVM extensions or rack installations.
At Kentek, we carry PS/2 cables, USB-to-PS/2 adapters, and PS/2 splitters for maintaining legacy keyboard and mouse equipment.