OLED Display Lets Vintage PC Engage Turbo Mode In Style

July 28, 2023 by Tom Nardi 10 Comments

Back in the 486 days, it was common to see a “Turbo” button on the front panel of many PCs, which was used to toggle between the CPU’s maximum speed and a slower clock rate that was sometimes necessary for compatibility with older software. Usually an LED would light up to show you were running at this higher speed, or if your machine was very fancy, it might even have a numerical display that would show the current CPU frequency.

[Joshua Woehlke] wanted to add a similar display to his 486, but figured that with modern technology, he could do something a bit more interesting. Especially when he realized that the spot on his case where the two-digit LED display would have originally been mounted was the perfect size to hold a common 0.96″ SSD1306 OLED. From there it was just a matter of wiring it up to an Arduino and writing some code to display different graphics depending on the computer’s current CPU speed.

Just like the frequency indicators of yore, the Arduino doesn’t actually measure the CPU’s frequency, it’s simply reading the state of the Turbo LED on the front panel. When the LED is off the Arduino shows an image of a i8088 CPU on the screen to indicate the computer is running in compatibility mode, and when the LED is on, the screen shows the Cyrix Cx486 DX2 logo. When the button hasn’t been pressed in awhile, the display defaults to a star field screensaver.

Regular readers may recall we recently covered a similar project that used an Arduino to add a little flair to an era appropriate seven-segment LED display. We’d say there’s still a good deal of romanticism about computers having a big “TURBO” button you can smash whenever you feel the need for speed.

486 Gets Animated Turbo Button Thanks To Arduino

July 25, 2023 by Tom Nardi 27 Comments

There was a point in time, excruciatingly brief, in which desktop computers often had a large “TURBO” button on their front panel. Some even featured an LED display that would indicate the current CPU frequency, providing visual conformation that your machine had leaped to a blistering 66 MHz.

The 486 that [someyob] is restoring had the Turbo button, but sadly there was just a simple LED to show whether or not it was engaged. But there was a window in the front panel where it seemed like a numerical display was intended to go, so they decided to wire up their own CPU indicator by sensing the state of the Turbo LED with an Arduino Pro Mini.

Now to modern audiences, this might seem like cheating. After all, the Arduino isn’t actually measuring the CPU speed, nor is it directly controlling it (that’s still done by the original Turbo button wiring). But the truth is, even back in the day, the CPU frequency displays faked it — they just toggled between showing two predefined frequencies depending on the state of the button. The arrangement [someyob] has come up with does the same thing, except now there’s some extra processing power in the mix, so the display can show some slick animations as it switches between 33 and 66 Mhz.

In the GitHub repository, [someyob] has provided the Arduino source code and schematics showing how the microcontroller was shoehorned into the existing front panel wiring without compromising its functionality. There’s even a brief video below that shows the display in operation.

Like the idea but don’t have a 486 laying around? Don’t worry. We’ve seen a similar panel built for modern machines that just doesn’t look the part, it actually manages to be functional.

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A personal computer drive bay with a glowing LED display

Turbo Button Pays Charming Homage To Early Personal Computers

November 3, 2022 by Chris Wilkinson 33 Comments

The PC turbo button and LED clock speed display were common features on early personal computers. Wanting to add a little retro chic to his modern battle-station, [Matthew Frost] assembled a charming and functional homage to the turbo button control panel.

In days past, this automotive nomenclature implied a performance boost when activated. Instead, ‘turbo mode’ would clock your x86 processor at its rated speed. Disabling ‘turbo’ would throttle the CPU, often all the way down to 4.77MHz. Inherited from the original IBM PC, some early computer programs relied on this specific clock speed, and would otherwise run too fast (or not at all) on faster hardware. PC marketing teams and engineers alike stopped including the turbo button and glowing clock speed numbers around the Pentium era.

This modern re-imagining of the turbo button uses an Arduino microcontroller, seven-segment display and tactile switches to emulate the look and feel of the original hardware. Instead of directly adjusting the CPU clock speed, hitting turbo switches between balanced and high-performance Windows power plans. The seven-segment display measures this clock speed in GHz to two decimal places. We’ll admit that it’s pretty satisfying to see those numbers inch higher when switching to turbo.

The rightmost button switches between measuring CPU speed, GPU utilization, network load and memory utilization, which improves on its original inspiration. The tubular key lock, also a common sight on early PCs, enables and disables networking for the entire system, which is great for keeping the kids off the ‘net (at least until they figure out how to remove the 5.25″ drive bay from the system and hot-wire the network adapter with a paperclip).

There are more details on the GitHub page, in case you want to build your own. This project could look especially fetching in PC sleeper builds, where new components are ‘hidden’ in old case hardware. And if this has made you feel nostalgic at all, you may want to hear our thoughts on why it’s all about the Pentiums.

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