Odd Inputs And Peculiar Peripherals: Utilizing A Commodore Mild Pen On A Fashionable(ish) Laptop

If you worked with personal computers back again in the 1970s, there’s a superior likelihood you employed a light pen at some issue: a easy input machine that you’d level at the CRT display screen to emphasize text, opt for menu solutions or manipulate graphic objects. While ubiquitous in those people days, the gentle pen misplaced the fight for ergonomics to the humble mouse and was all but extinct by the late 1980s. Touchscreen styluses implement a comparable function now, but touching the monitor somehow doesn’t really feel the same as basically pointing at it.

We thus applaud [Maciej Witkowiak]’s efforts to carry the light-weight pen into the 21st century by building a USB interface for a Commodore 64/128 gentle pen. At its heart is an Arduino Micro Pro that implements the USB HID protocol to converse with any modern day personal computer. It connects to the traditional light-weight pen as properly as to the computer’s analog display screen signal and works by using those people to calculate the hold off among the video synchronization pulses and the light pen’s output. The sync pulses are extracted from the movie sign by an LM1881, a sync separator chip that will be familiar to anyone who’s labored with analog online video alerts.

The Arduino calculates the light-weight pen’s position dependent on the calculated timing intervals and stories it to the laptop, using the absolute positioning method which is also utilized by factors like drawing pads. [Maciej] demonstrates his technique in the video clip embedded below, in which he utilizes it to operate the menus on an X window system. A good achievement then, while there is a single catch: gentle pens only function on CRT shows, so you’ll have to have to drag 1 of these big glass beasts out of storage if you want to try this on your own.

We have highlighted the Commodore gentle pen in advance of in this odd gaming input machine. A equivalent device designed with a discrete LED matrix is a great illustration of the light-weight pen’s operating principle.