I once tested all of my MMX chips, but I don't remember where I wrote down the results and if I ever posted my results here. I only tested for their maximum multiplier btw, iirc.
And in the end it appeared that some had some of their multipliers disabled and some were multiplier free.

I do remember a webpage that explained how after a specific date chances increased the lower speed chips had disabled 3.5x multi etc, but can't really remember as it is so long ago.

I still have the p233 mmx installed, but now I'm curious about the x1.5 multi and may swap the p200 back in test it out. If I do I'll report back..

tincup wrote:

I still have the p233 mmx installed, but now I'm curious about the x1.5 multi and may swap the p200 back in test it out. If I do I'll report back..

AFAIK the MMX do not have a 1.5 multiplier, 2x is the lowest.

The standard Pentium interprets 3.5 as 1.5x or something like that.

Hmmm.. my notes in the margins of my AN430TX manual show I under-clocked the P200 mmx to 90mhz using 60mhz @ x1.5 jumper settings. Notes also indicate I could not achieve the same result using a P233 mmx - it read the x1.5 jumper setting as x3.5.

I'll definitely give it a try.

I stand corrected. None of the MMX cpus saw the x1.5 multi, but the non-MMX did. Bad notes haha!

No problem, thanks for checking.

gerwin wrote:

Pentium MMX 200 SL27J 5.4.3 - 2.5x, 3.0x

just for the record with that one I can get it working on: 120Mhz, 150MHx, 180MHz and of course 200MHz.

Pictures of the CPU and screenshots from SpeedSys are attached.

On 120Mhz with cache disabled it goes does to 386DX 40Mhz.

So, those are the modes - 4 possible speeds and with cache disabled depending on the speed it is between 386DX 40Mhz and 486DX2 50Mhz (it cannot reach that speed and it's less than that and so maybe it's more correct to say between 386DX and 486DX 40Mhz).

There is some understandable confusion about this.

Believe it or not some same s-spec chips from intel can display as many as three different behaviors when setting multipliers.

For example, from my recollection when testing my pile of pentium mmx chips I would find some same s-spec chips that would set 3.5x, 2.5x and some that would set 2x all from the same mobo setting. Just switching cpus. This seems to be a result of the locking that intel started doing in these chips around this time.

So It’s understandable that people would test these and post different results online calling the other person wrong 🤣

The desktop pentium 1s respond to two signals, BF0 and BF1 while there were plans it seems to install a third signal (BF2) this signal ended up on a different pin than on AMD K6 but apparently intel had implemented their version of it to some degree because the tyan s1564d has a pull down jumper for it (missing a pull up though) this BF2 intel pin did end up getting used on the mobile Tillamook. But the intel iteration of this pin kinda got forgotten to time and motherboard manufacturers because by the time super socket 7 was around they were only using AMD’s BF2 location which was also used by Cyrix (IBM/ST) for setting 1x and 4x if I recall correctly. But rise and winchip still only used the BF0/BF1 pins.

More info:
Socket 5/7/SS7 (Motherboard) Tweaker (Released)

To asnwer OP:

There are some select motherboards with a 7mhz fsb option. Given that the lowest multiplier supported by pentium on socket 5/7 1 is 1.5x you could in theory get a pentium 1 75-200 non mmx running at 10mhz or around abouts.

Lucky Star 5V-1A / 5V-1B review - scaling form XT levels to K6-II levels

Isn't it great that a question from 2009 is finally answered in 2022? 😜
Apparently I wasn't even sure myself back in 2014 😜

Tetrium wrote on 2022-04-27, 19:34:

Isn't it great that a question from 2009 is finally answered in 2022? 😜
Apparently I wasn't even sure myself back in 2014 😜

That happens sometimes 🤣

What was it?, 20 years after release of the tillamook that we finally figured out how run them on desktop boards.

There is also the k6-2+ to 3+ mod which was only figured out recently.

In any case the thread was prominent on a google search and I had relivant info to add, last post wasn’t all that long ago.

Sphere478 wrote on 2022-04-27, 22:41:

That happens sometimes lol […]
Show full quote

Tetrium wrote on 2022-04-27, 19:34:

Isn't it great that a question from 2009 is finally answered in 2022? 😜
Apparently I wasn't even sure myself back in 2014 😜

That happens sometimes 🤣

What was it?, 20 years after release of the tillamook that we finally figured out how run them on desktop boards.

There is also the k6-2+ to 3+ mod which was only figured out recently.

In any case the thread was prominent on a google search and I had relivant info to add, last post wasn’t all that long ago.

Yes, personally I wasn't expecting a proper solution anymore, but apparently it kinda works now 😋
Even further back we didn't even know how to overclock (or underclock) 486 boards or knew about unlocked (and locked) Deschutes 😜

gerwin wrote on 2014-03-13, 21:45:

I cease to believe 1.5x exists on a retail MMX. Unless someone has better prove of it, like a Speedsys screenshot.

Ok, got Pentium 100 MMX at least on screen in BIOS. 😀 3.5x multi it interpretes as 1.5x hence 66x1.5 = 100. The other multis are 2x (that works normaly), 2.5x but 3x it interpretes as 2.5x. So result is: 2x, 2.5x , 2.5x, 1.5x (instead 3.5x)
Original CPU is Pentium 166MMX. To be honest, I am shocked they are locked / limited somehow, I thought they were unlocked like regular Pentium 1's, just should have 3.5x instead 1.5x. But I see , I was wrong.
Today, I've tested QDI Explorer II Speedeasy build (all in case, with Pentium 166 MMX inside , so I didn't wanted it to decompose), so I of course was tempted to play with multis, because it was Speedeasy (would not probably messed with jumpers) but actually wanted only test, if board is fine, so it's more of a lucky finding, as I wanted only spend 30 seconds on it, if board is fine. I've changed multi to 2x in BIOS at first, and it showed 133 MMX, so everything looked regular, so even more luck, I continued, so then I've tried 3x, if CPU handles 200mhz overclock(didn't want to try more). And here came first unregularity... to my suprise, it showed still 166MMX. So I've tried 3.5x, what result will be, and stood shocked. It showed Pentium 100 MMX.

W.x. wrote on 2022-11-18, 16:31:

Ok, got Pentium 100 MMX at least on screen in BIOS. :) 3.5x multi it interpretes as 1.5x hence 66x1.5 = 100. The other multis ar […]
Show full quote

gerwin wrote on 2014-03-13, 21:45:

I cease to believe 1.5x exists on a retail MMX. Unless someone has better prove of it, like a Speedsys screenshot.

Ok, got Pentium 100 MMX at least on screen in BIOS. 😀 3.5x multi it interpretes as 1.5x hence 66x1.5 = 100. The other multis are 2x (that works normaly), 2.5x but 3x it interpretes as 2.5x. So result is: 2x, 2.5x , 2.5x, 1.5x (instead 3.5x)
Original CPU is Pentium 166MMX. To be honest, I am shocked they are locked / limited somehow, I thought they were unlocked like regular Pentium 1's, just should have 3.5x instead 1.5x. But I see , I was wrong.
Today, I've tested QDI Explorer II Speedeasy build (all in case, with Pentium 166 MMX inside , so I didn't wanted it to decompose), so I of course was tempted to play with multis, because it was Speedeasy (would not probably messed with jumpers) but actually wanted only test, if board is fine, so it's more of a lucky finding, as I wanted only spend 30 seconds on it, if board is fine. I've changed multi to 2x in BIOS at first, and it showed 133 MMX, so everything looked regular, so even more luck, I continued, so then I've tried 3x, if CPU handles 200mhz overclock(didn't want to try more). And here came first unregularity... to my suprise, it showed still 166MMX. So I've tried 3.5x, what result will be, and stood shocked. It showed Pentium 100 MMX.

Can you post a high res pic of this chip front and back please.

W.x. wrote on 2022-11-18, 16:31:

"It showed Pentium 100 MMX."

A BIOS detection bug? Need to verify with one or more programs which do a raw measurement of the CPU cycles per time.

I’m thinking glitch. Lowest mmx pentium I know of was a pentium 120 mmx I assume 60x2

Which is why I wanna see the chip 🤣 :p

Sphere478 wrote on 2022-11-18, 16:42:

Can you post a high res pic of this chip front and back please.

It's SL27K
manuf date is 9th week of 1998, otherwise it looks just like any other P166MMX (ceramic one), on net
https://www.cpu-world.com/sspec/SL/SL27K.html

It looks just like this one
http://cdn.cpu-world.com/Images/uploaded/0001 … /L_00015345.jpg

just code in second line start with 8809

today, I had some work on computer, so I've pulled it out.

Today, I've come across another Pentium 166 MMX, same type - SL27K (so I have two of them ). I've got two another socket 7 boards, this time with VIA VPX/97 chipset.
This one is earlier, date code is 9740 so 40th week of 1997.

I've tested both of them on FIC VA-502.

So QDI motherboard had probably BIOS detection bug.
Because this time, on FIC VA-502, it ended like this:

1,5x is interpreted as 2x.
2x is interpreted as 2x
2,5x is interpreted as 2,5x (this is defuault for both of them)
3x is interpreted as 2,5x

so it's 2x,2x,2,5x,2,5x type. Hence, it cannot be overclocked, and you can forget about Pentium MMX 200 from it. I'm sure Intel made this as some overclocking protection.

My win98 HDD cannot be booted on this motherboard and I don't know why, (it worked on every motherboard till now, I've tested like 100 of them) so I cannot test it under my stardard tests. So it's only from post screen, not confirmed by those detection programs.