Bottom right by the resistor is H C L which is for the turbo switch HIGH COMMON LOW. I can't see the bottom two right pins, but they are likely +5/GND.

The rest of the pins are setup like any other turbo switch with the triangle jumper config of OFF, always on, turbo only, non-turbo. Top row of two pins is hundreds, second row of two pins is 10's, bottom row is one's.

Also, don't be surprised if there are burned out segments. About half the ones I've received from Ebay have dead segments. These turbo displays are designed cheaply/poorly and don't implement 1 resistor per segment to limit current.

I actually designed a 3-digit ATTiny turbo display off this ebay listing 🤣 (well, the mounting and digit size) Re: Fabricating a New Turbo Display

wiretap wrote on 2021-08-03, 20:37:

Bottom right by the resistor is H C L which is for the turbo switch HIGH COMMON LOW. I can't see the bottom two right pins, but they are likely +5/GND.

The rest of the pins are setup like any other turbo switch with the triangle jumper config of OFF, always on, turbo only, non-turbo. Top row of two pins is hundreds, second row of two pins is 10's, bottom row is one's.

Thank you for the response. You were correct, just tested it. The first lower bottom right pin (next to resistor) is Ground , the second one to the left of it is +5V.

Regarding L C H, how would I hook it up in my setup?

The case has:
- Turbo button with long 3 wire cable labeled Turbo Switch which I believe is intended to plug to motherboard to trigger Turbo on/off
- LED diode with long 2 wire cable labeled Turbo LED, which needs 5V
The motherboard has
- Turbo LED 2 pin header that is suplying 5V (4.7v)
- It doesn't have Turbo Switch header, the manual says Turbo on/off should be triggered via software, which I assume is some keyboard combination, which I don't know which, because I only have few pages from the original manual and they don't cover the keyboard combination, my guess is some sort of Ctrl+Alt+PgUp/Dwn, will have to try it someday.
- Motherboard is model MSI MS-6103 with 200Mhz Dual PPro CPU. I have no idea what Turbo Off would actually do with this combo, will have to try one day and benchmark it.

The easiest thing is to just feed 5V to the LED, set it to 200Mhz and forget Turbo on/off.

But if I wanted to hook turbo on/off, how? Here are my thoughts:
Assumptions: the motherboards Turbo LED by default provides 5V, when Turbo is switched via Software key combination, the motherboard turns off the voltage.
The Physical turbo button is useless as the the motherboard doesn't have Turbo Switch header. Maybe I could wire it to FSB, but I'm not gonna mess with that, and will just rely on Software Turbo switch. I will therefore leave Turbo Switch button cable disconnected.
I will connect the the motherboards Turbo LED two pin header to H C on the LED display. This should trigger a change on the display when Turbo is switched on the board via Software.
I still need to hookup the Turbo LED diode on the front the case: I could either not care about it since the MHz display will clearly show different values, therefore there's no need for another LED. Or, I could split the 5V line from the Turbo LED header on the motherboard into two, and run one line to H C on the LED display and the other pair to the LED diode on the front of the case. That's actually how it's implemented on a different LED display I have in another case, where the LED display had two Turbo LED headers. One to trigger from the the board and second one to send 5V to Turbo diode.

EDIT: I don't think what I wrote above about H C L being connected to Turbo LED will work. H C L doesn't need any external 5V power, it already has it on C pin, it just needs a ground on either H or L. Just tested it . So that means there's likely no way to trigger H C L from 5v Turbo LED signal. The only way is from physical Turbo button that bridges H-C or C-L, which I can't use since the Turbo button doesn't really do anything in my case as it's missing connection to trigger motherboards Turbo on/off.

Thoughts?

Thank you.

With a PPro board like that, I don't think there's any turbo functionality. Since there's no turbo switch pins, you're better off just having the display mounted in the case fixed to 200MHz.

As for a turbo display functioning off the turbo LED of the motherboard, that's how I designed my ATTiny85 turbo displays.

wiretap wrote on 2021-08-04, 00:14:

With a PPro board like that, I don't think there's any turbo functionality. Since there's no turbo switch pins, you're better off just having the display mounted in the case fixed to 200MHz.

What's curious is this statement in the board's manual: "Turbo LED can be controlled by Software Turbo/Deturbo". It's little bit ambiguous, but maybe...

I have a Pentium board that has a turbo switch and LED header. It makes the display and turbo LED change, but it does nothing other than that.

Maybe your board is different. It could change FSB or disable cache. You'll have to experiment and find out.

Finally got to test Turbo on/off functionality on this board. It does actually work via SW. Pressing CTRL + ALT + Num +/- triggers Turbo On/Off. When turning it off (slowing down), the computer hangs about 15 seconds and then the new slower speed kicks in and everything resumes. When turning it back on, the switch happens instantly.

I did a quick benchmark with Landmark 6.0.

Turbo On:
CPU: 2,491 MHz
FPU: 3,099 MHz

Turbo Off:
CPU: 18MHz
FPU: 68MHz

I was shocked when I saw this. First that the turbo on/off works at all on Dual Pentium Pro board with dual PPro 200/512kb, and 2nd at the amount of slow down that can be achieved. I didn't do any other test to see how stable it is and if some speed sensitive games would indeed run well. Will have to do that next.

Also tried to connect the HW Turbo button to the board, but that didn't do anything, beyond switching the Turbo LED header on the motherboard on and off, but internally the board wasn't adjusting the speed - that has to be done via CTRL ALT +/-

Wow, that's some brakes, must take 15 seconds to fire the parachute, throw an anchor out and prime and ignite the retro booster. I must admit I haven't done serious turbo testing on many later boards, my 5x86 system I never quite figured out what it did, in the Norton Sysinfo bench it only went down from about 443 to 280 and I never figured out quite what it was doing, "too fast" DOS stuff was still too fast, put a minor crimp, felt like about 20% on Doom and Quake, Windows felt pretty much unaffected. So I assumed from then on that Pentium class systems didn't really deturbo. Think I tried it on a P100 with similar feeble results before that conclusion really set in.

Did some more testing with the Turbo functionality:

- It definitely works, tried Wing Commander 1, Test Drive 3 which are speed sensitive. Also tried Silpheed, Test Drive 1 which worked fine. Also tried Donkey Kong, but the system was still about 2x too fast than it should be.
- Also confirmed that the Turbo Off is instant if done within DOS, my previously reported 15sec delay was only when triggered inside of a game, outside of game or benchmark app it's instant.

I must say I'm happy about this surprise deturbo feature.

That's pretty awesome. Glad to hear it has functionality.