Oh, I forgot to mention an important thing. The board supports 168-pin SDRAM, and 72-pin SDRAM modules (not both at the same time though). I tested with a 32MB 168-pin module. According to the manual, it shouldn't matter which SDRAM slot the module is in. But with the module in the topmost slot, the motherboard didn't post at all. It only posted when I moved the RAM to the second slot.

pictures and remarks and FSBs added to the page. Can you make a bios dump as well? Since you have a different version.

It took me a while to figure out what chip the BIOS is, because I didn't want to peel the sticker. Turns out it's an Atmel 29c010A. It's now dumped, attaching here.

POST string: 09/25/97-i430TX-SMC669-2A59IV3FC-00
so it appears the BIOS is older than the other versions available at ultimateretro
This motherboard has an SMC I/O chip if it makes a difference.

Just for fun I did some stability tests with the P200MMX. At 75x3=225 it is completely stable. At 83x3=250 it crashes randomly even if I raise Vcore to 2.9V. I did not want to go to the next notch which is 3.2V. I guess it makes sense why Intel didn't sell PMMX above 233MHz. 😀

Thanks ! Am always interested in old Pc Partner stuff !! It even has the PcP part number labeled on the board....
Many do not know they (Vtech) also did many Leading Technology computers too.

Lol it says 430tx at the bottom of post :p

Looks like you need a k6-2+ 570 for that beast 😀

83.3x6x = 499.8mhz

And a visit here http://web.inter.nl.net/hcc/J.Steunebrink/k6plus.htm

I don’t see your board listed but member chkcpu may be able to help. (Same guy as website)

Your voltage options for 2v are probably all jumpers off.

stamasd wrote on 2022-01-19, 19:29:

Oh, I forgot to mention an important thing. The board supports 168-pin SDRAM, and 72-pin SDRAM modules (not both at the same time though). I tested with a 32MB 168-pin module. According to the manual, it shouldn't matter which SDRAM slot the module is in. But with the module in the topmost slot, the motherboard didn't post at all. It only posted when I moved the RAM to the second slot.

Actually if you find out how the board is laid out you can often use sd and edo at the same time. Usually this requires leaving a slot open. Because some lanes are shared between the simms and dimms.

Sd performance on tx is pretty abysmal so if you have a couple 128mb simms laying around throw em in!

The board will have a max of 256mb of ram. (Chipset limitation, no way around it)

If you need, I can tell you of some 256mb sd sticks that work with it. But as said, max of 256 total.

stamasd wrote on 2022-01-19, 22:17:

Just for fun I did some stability tests with the P200MMX. At 75x3=225 it is completely stable. At 83x3=250 it crashes randomly even if I raise Vcore to 2.9V. I did not want to go to the next notch which is 3.2V. I guess it makes sense why Intel didn't sell PMMX above 233MHz. 😀

May I introduce you to the tillamook pentium mmx 266?

stamasd wrote on 2022-01-19, 22:17:

Just for fun I did some stability tests with the P200MMX. At 75x3=225 it is completely stable. At 83x3=250 it crashes randomly even if I raise Vcore to 2.9V. I did not want to go to the next notch which is 3.2V. I guess it makes sense why Intel didn't sell PMMX above 233MHz. 😀

What happens if you lower the multiplier? Those crashes at 250MHz could be due to CPU, but also due to IDE or other bits not liking the 41.6MHz PCI. The K6-233 results certainly suggest it's not CPU-related.

If it is the FSB that's the problem you could try it on 3.5x 75MHz if the CPU's not locked.

Edit: missed that the CPU was locked. Note that you might still be able to lower multiplier, the lock on the P55C was generally on just one or two multiplier settings.

dionb wrote on 2022-01-20, 11:20:

Edit: missed that the CPU was locked. Note that you might still be able to lower multiplier, the lock on the P55C was generally on just one or two multiplier settings.

I did try all of the multiplier jumper settings with the p200MMX, it did not make any difference. The multiplier always stays at 3x.

Sphere478 wrote on 2022-01-20, 06:47:

Lol it says 430tx at the bottom of post :pa

Yes, but sometimes the BIOS string lies. I had to check, especially since TX didn't officially support those FSB settings.

Sphere478 wrote on 2022-01-20, 06:47:

Looks like you need a k6-2+ 570 for that beast 😀

I have one somewhere, need to find it. But the max multiplier I can set with this board is 3.5x, unless I misunderstand how multipliers work on k6-2. Guess I could use an utility like SetMul to set different multipliers.
(edit) oh wait, K6-2 interprets 2x as 6x, nice. So I could theoretically get to 83x6=499MHz. Assuming it likes the 83FSB, which it should. And that the other parts of the board are OK with it too. Worst case, I can mod the clock chip to force async PCI clock of 32MHz regardless of FSB, which it does support (see first post). A pull-down 10k resistor from pin 32 to ground should do that according to the datasheet.

Sd performance on tx is pretty abysmal so if you have a couple 128mb simms laying around throw em in!

I plan to eventually, but for now I just did this quick testing with the 32MB which I had laying around.

May I introduce you to the tillamook pentium mmx 266?

I have one of those somewhere in a box too, have to find it. 😀
Isn't the Tillamook problematic in many ways though, as in L2 cache not working, having oddball I/O voltage (2.5V instead of 3.3V) etc?

Further work that I've done on this board, which I want to complete before I build something with it.
I want to determine the pinouts of the mouse connector, and of the USB connector. They appear to be non-standard, so I took out a multimeter and an oscilloscope to try and determine which pin is which.

First, the PS/2 mouse header. It has 5 pins arranged vertically which I've numbered arbitrarily 1-5 from top to bottom.

Pin 1: 0V at power on, goes to 5V after POST is done (immediately after the memory count is finished) and stays there, no waveform on it
Pin2: 0V, stays low all the way to a complete boot of DOS, no waveform
Pin3: 5V at power on, briefly dips to 0V after memory count is done and then immediately returns to 5V and stays there, no waveform
Pin4: same as pin2, stays at 0V all the time, no waveform
Pin5: 5V immediately at power-on and never changes

Second, the USB header. It has 2 rows of 4 pins arranges horizontally. I have numbered arbitrarily the top row 1-4 from left to right, bottom row 5-8 from left to right.

Pins 1,2,3,6,7 and 8: oV all the time with no waveforms on any of them
Pins 4 and 5: 5V all the time with no waveforms

Any help appreciated. The board manual has no information on the pinouts of these two headers. I made sure USB is enabled in BIOS of course.

Photos of the headers, and how are they numbered? USB headers are often something like (often with a 5th row with only 1 pin to orient the connector):

1+5V  1  2  +5V
2D1-  3  4  D2-
3D1+  5  6  D2+
4GND  7  8  GND

With the board off you could try measuring the resistance of the 0V pins to ground. Only two should be shorted to ground, which are the GND pins. If you find those, there aren't many options for the data pins.

Looking at a pinout I found for another (unknown) PCPartner board, that gives USB as:

11 - Vcc
22 - GND
33 - P1-
44 - P0+
55 - P1+
66 - P0-
77 - GND
88 - Vcc

which is a bit weird.

For the PS/2 it sounds like clock and data are on pin 1 and 3. I don't know which way around, but for PS/2 the host holds clock low to stop the device sending any data. It can signal the device that the host wants to transmit by pulling data low, then releasing the clock. Part of POST will transmit a reset and ID instruction to anything on the PS/2 port, which means it has to transmit to the device, so would need to pull clock low, pull data low, release clock.

So I'd guess that Clock is on your pin 1, since I think it'd make sense to stop a device transmitting until the BIOS was ready. Then it sounds like pin 5 is +5 supply, then 2 or 4 is Ground (I'd guess they had an option of missing one out to make an orientation header). Based on that I'd guess at:

11 - Clock
22 - Ground
33 - Data
44 - NC
55 - +5V

Again, with the board off you can check about which pins short to either ground or +5 to get the power pins, which only leaves a couple of possibilities for the Clock and Data.

This other PCPartner board (I don't actually know which model it is) has the PS/2 pinout of:

1Data 1  2 NC
2GND  3  4 +5V
3Clk  5  6 NC

That matches the PS/2 connector layout.

If you do get them working, please report what the pinout actually is. I haven't been able to find a good source for the PCPartner pinouts.

Thanks, that should get me going. The pins aren't numbered in any way on any of those 2 connectors.
I think for the USB the first pinout in your post should be correct @snufkin, turned over 90 degrees clockwise for the top row and counter-clockwise for the bottom row. So that's nonstandard compared to modern USB pinouts where the +5V , data lines and ground are in the same columns next to one another.

And for the PS/2 probably the 3rd pinout is correct. I will test and post back. Actually I can't test for the PS/2 until the bracket I ordered gets here and it may be a few days.

Here is a pic of the mouse and USB headers, numbered as I described them above (red for mouse, blue for USB)

Yeah I've tested both halves of the USB connector (one at a time using a standard USB bracket, because the second half has the wrong polarity if inserted normally) with a USB keyboard, and it's correct. I'll have to make an adapter to cross over the signals and make them match the pinout of the 2nd half of the connector on the USB bracket.

So using the numbering in the photo, the pinout for USB on this motherboard \ is:
1. GND
2. D1+
3. D1-
4. 5V
5. 5V
6. D2-
7. D2+
8. GND

with pins 5-8 flipped 180 degrees from what they are on a modern USB header.

(update) I've actually managed to pull the wires from half of the USB bracket connector and reverse them WITHOUT destroying the connector completely. 😀 A bit of glue and tape, and now both ports on the USB bracket work correctly at the same time. Tested with the same USB keyboard.

stamasd wrote on 2022-01-20, 17:40:

Yeah I've tested both halves of the USB connector (one at a time using a standard USB bracket, because the second half has the w […]
Show full quote

Yeah I've tested both halves of the USB connector (one at a time using a standard USB bracket, because the second half has the wrong polarity if inserted normally) with a USB keyboard, and it's correct. I'll have to make an adapter to cross over the signals and make them match the pinout of the 2nd half of the connector on the USB bracket.

So using the numbering in the photo, the pinout for USB on this motherboard \ is:
1. GND
2. D1+
3. D1-
4. 5V
5. 5V
6. D2-
7. D2+
8. GND

with pins 5-8 flipped 180 degrees from what they are on a modern USB header.

On the plus side, that arrangement has rotational symmetry, so it doesn't matter which way around the connector goes.

snufkin wrote on 2022-01-20, 18:17:

On the plus side, that arrangement has rotational symmetry, so it doesn't matter which way around the connector goes.

Yes, this is probably why they did it that way. And it makes sense. It could have become the standard.

Would you mind checking which pins on the Printer and COM headers are short to Ground? That way it might be possible to have a stab at working out the pinouts for those headers as well. If those are worked out then I think it just leaves the FDC and IDE headers, and they must surely (famous last words) follow the normal pinout.

I don't see anything too unusual about this board. 75MHz and 83MHz for FSB were somewhat common, although obviously unsupported on the chipset. Not too shabby either way! If your CPU can take it (and that's almost certain for MMXs), the 75MHz FSB option is almost always guaranteed to work flawlessly. The slight increase on the PCI bus isn't enough to cause issues and in fact I've read magazines from that era that recommended it for light overclocking with a decent bump in performance. I'd use it, personally.

The 83MHz FSB bus however is another story, most devices won't be able to handle it. The PCI bus runs way too high at that speed courtesy of lacking a proper divider. I've heard tales of people using that bus setting and getting it stable with cherry picked hardware (including the motherboard I believe), but honestly I think it's way too much of a headache. 75MHz on the other hand is a nice, healthy boost in performance and generally trouble-free.

Garrett W wrote on 2022-01-20, 19:06:

The 83MHz FSB bus however is another story, most devices won't be able to handle it. The PCI bus runs way too high at that speed courtesy of lacking a proper divider.

Like I mentioned above, this board's clock generator has the ability to run the PCI clock at a constant 32MHz independent of the FSB. It needs a slight hardware mod to enable that. I will get around to that, eventually. It's in the datasheet I posted a link to in the first post.

Frankly, what makes this motherboard interesting above others is that particular clock chip. With the option to run PCI async.

snufkin wrote on 2022-01-20, 18:44:

Would you mind checking which pins on the Printer and COM headers are short to Ground? That way it might be possible to have a stab at working out the pinouts for those headers as well. If those are worked out then I think it just leaves the FDC and IDE headers, and they must surely (famous last words) follow the normal pinout.

the IDE, floppy, serial and parallel headers have pin 1 silkscreened on the board. The IDE ports work and have the normal pinout. The serial and parallel port headers have GND exactly where you expect them (just checked - i.e. COM pin 5, and LPT all even pins from 10 to 24), so I think safe to assume standard pinout too. The only one I haven't checked yet is the floppy header, and I have no reason to believe it's not standard.