Some vintage computer keyboards, especially units like the IBM Model M, are still quite desirable. Usually they’re popular among mechanical keyboard or retro computing enthusiasts who want period-correct hardware. YouTuber Midwest Cyberpunk had thousands of these old keyboards and needed a way to test them. So he built this small Arduino-based device that displays the text input from PS/2 keyboards.

IBM developed the PS/2 port standard in the ’80s for the IBM Personal System/2 series of computers. By the ’90s, it was the standard for connecting keyboards and mice to PCs. USB made the PS/2 port almost obsolete in the ‘00s, which means that there aren’t many modern computers that still have PS/2 ports. Midwest Cyberkpunk could have used a vintage computer for testing his keyboards, but wanted a more portable option. This PS/2 Keyboard Tester device is easy to carry and provides instant results.

Inside of the custom 3D-printed case is an Arduino Nano, a homemade breakout board, a LiPo battery charger and booster board, and a 16×2 character backlit LCD. The Arduino sketch utilizes a PS/2 library that can read the character hex codes from standard keyboards. Once powered on, Midwest Cyberpunk can simply plug the keyboard into the device. Any key he presses on the keyboard will show up on the LCD screen, so he can quickly press every key to ensure that they all work. It is an efficient and affordable way to test large quantities of vintage keyboards in a short amount of time.