OLED Display Lets Vintage PC Engage Turbo Mode In Style

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.

10 thoughts on “OLED Display Lets Vintage PC Engage Turbo Mode In Style

  1. I guess using a Mega for driving a single SSD1306 isn’t much crazier than putting it in a 486. More like a job for a $2 MH-Tiny or something else that’s just as cheap, but you use what’s at hand. I’d swap it out later, so I could use the Mega for something a little more substantial, though.

    1. Or PIC16F84A (now vintage).
      Love idea with the Starfield simulation, though.
      Makes me wonder if something similar, like Marquee or Mystify, was possible with a segment display (16 segment).
      A magic eye would be cool as a speed display, too.

  2. I love stories like this. And especially since I can just hear Tom’s voice reading the story after listening to him so many times on the podcast. For the project owner: how about displaying the Game of Life on the tiny OLED also in between star field showings? :-)

  3. This a nice cabinet mod. Wish they had it back in the day. Long ago at our university one of the departments bought a bunch of hand built computers from a business that sold office equipment and repaired typewriters (they’d been around since the thirties). The department director asked me to change out a power supply one day because the office company was behind on services calls (more on that) I changed the p/s and discovered the turbo button did only one thing… it only turned on the turbo light.. wasn’t connected to anything on the mobo. Fake turbo mode ! I also discovered that hot glue was used to hold the mobo to the standoffs and other cheap construction tricks. Seems their POS’s had a high failure rate. The department director was not happy. This was right before Y2K and that junk failed testing. He had me replace all of them with Dells (university spec’d) and turned over support to my department. Oh that office company quit making PCs that year and had to refund a lot of money and then went out of business. The son of the owner was the one building PCs to make some quick money. Fake Turbo…. LOL…

    1. But somebody (you) had to open up one of the PCs to discover the fraud!
      And since the store had the exclusive Service Contract, they figured they were quite safe getting away with it.

    2. “The son of the owner was the one building PCs to make some quick money. Fake Turbo…. LOL…”

      Hm. Maybe that son was under pressure and had to be creative. I mean, we don’t know if the father was a nice father and whether or not the company had already been struggling at this time. I’m not defending things here, I just think it’s human. Cheating with the Turbo button is one of the less harmful “crimes” I could think of. Cheating with hard drive capacity (installing SmartDrive secretly and accepting money for a fake HDD upgrade) would have been worse, maybe.

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