Cool built!

When I was a kid I mounted switches to the front of the case and connected the wires to the FSB and Multiplier pins of a AMD 486DX-4 😀

Allowed me to go from a DX2-50 to a DX4-120.

Looks like your system has everything one needs for DOS gaming!

Sounds good. Fix pictures please 😀

Thanks. Just figured out how to use Imgur so pictures should be fine now.

Mau1wurf - I like this switch setup, it's a good way to make a mainboard that is not jumperless a bit more flexible, and also you don't even need to go into the BIOS to adjust the speed of the system. Just turn off, adjust the switches on the panel, and turn it back on.

Hi and welcome, looks like you have the serious retro bug already. Hanging around here only seems to feed it!
I felt your pain, the amount of nice old hand me down PC's and cases I trashed casue they were old. Now are worth so much!
Looks likes a nice setup, It'll be interesting how long to those little things like the front panel not fitting drive you mad and you start fiddling again
(again I blame vogons)

Nice build, want some inside shots 🤣

Why the CM-32P? Isn't it useless for gaming purposes?

Very nice machine. Nice MIDI setup as well. 😀

It's sooo cute!! why didn't you go with a lower clock speed? say-166MHz?

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Just let me get one thing straight. You DO have to power off the system before changing speed settings, right?

Actually I never tried to adjust the speed "on the fly" because I didn't want to risk damaging anything. I no longer have this system so I can't test it unfortunately.

How did you wire up the panel with the switches for changing CPU speeds? Something like that would be very nice to have.

I wasn't aware that you could underclock Pentiums like that. Are they multiplier unlocked?

The original Pentiums in general didn't have locked multipliers. Intel first did that with some Pentium MMX so you couldn't just run them at 233 MHz (which probably all of them would have been capable of).
Another way to see this is that early Pentium MMX CPUs just didn't substitute 3.5x for the 1.5x setting like later ones did.

How can I tell if my P200 MMX is one of the unlocked models?

If it is, then I assume it would just be a matter of installing a bunch of switches to control open or closed states of the jumpers that control CPU speed. Is that correct?

Indeed, at the time I bought a 5"1/4 front panel with 4 switches from frozencpu.com, then connected the switches to the jumpers that control FSB speed and multiplier on the motherboard.

I have since given away this system and replaced it with a P233MMX build. It has a simpler setup with 2 switches at the back - it can run at 100, 133, 166 or 233mhz.

I always thought that Pentiums MMX were unlocked though, and that Intel started locking multipliers shortly after releasing the Pentium II.

MMaximus wrote:

Indeed, at the time I bought a 5"1/4 front panel with 4 switches from frozencpu.com, then connected the switches to the jumpers that control FSB speed and multiplier on the motherboard.

I have since given away this system and replaced it with a P233MMX build. It has a simpler setup with 2 switches at the back - it can run at 100, 133, 166 or 233mhz.

I always thought that Pentiums MMX were unlocked though, and that Intel started locking multipliers shortly after releasing the Pentium II.

This has actually given me some ideas. My pentium 1 systems force a clock multiplier by the use of DIP switches-- I wonder if I popped a 200 Mhz chip if it would force it to run at 233 Mhz. I know the reverse is true (I was running a 233 at 50 Mhz with some undocumented mode by accident).
However, it would be really cool to desolder the DIP switch and break out the interface to the front of the computer by the use of four switches or something to specify which CPU speed I want. Another method would be to create a system of relays to mimic the DIP switch, but have a software driven LCD interface dynamically set the appropriate mode-- only caveat is that it would have to be powered on while the computer itself is not. I have no clue what will happen by dynamically changing your clock multiplier on-the-fly, probably some weird glitching and then a system freeze I would imagine.

what motherboard is your new pentium system?

sorry for the late reply... I'm now using an ASUS VX97: Pentium 233MMX - SCC-1 / CT2230 / Voodoo2 rig.