Tetrium, I'm not sure if I am right about this, but your webpage link gave me an idea. I looked at the top of this table, from your webpage link, and saw the column heading labelled P55C. Then, looking down this column, I noticed that one table cell contains the text "BF0" and another cell contains "BF1". This info is:

Y33 BF0
X34 BF1

I am wondering if the pins Y33 and X34 need to be bridged/connected?

Tetrium wrote:

Still I'm not sure how shorting B0 and B1 ups the multi to 4.5x.

I wonder if this can be rephrased, in order to look at this situation from a different perspective? Let's say that B0 and B1 on the CPU have been shorted. Perhaps that makes the CPU "unaware" of what its default multiplier is. So, using your mobo's jumpers, you can set these mobo jumpers to a higher CPU multi value; greater than 3.5x. The CPU will not complain, because it has now "forgotten" what its default multi is. What I am suggesting is that, in theory, the CPU's multi could go beyond 4.5x. It could go up to (or down to) whatever value the multi can be set using the mobo's jumpers.

BF2: W35
BF1: X34
BF0: Y33

These 3 pins are located right next to eachother, which is a + 😀
Shorting 2 of these pins while setting motherboard jumpers (1 shorted one way, one the other) sounds risky, wouldn't that cause a short?
I do know that having BF0 and BF1 float (not jumpered) 'should' cause the P1 mmx to set to 2x multi iirc

Hold on, I just remembered something.
I did once see a pic of a PPGA chip with 2 shorted pins but can't remember where I got it. It mentioned Tillamook also but of that, I can't be sure.

The good news is, I might actually have this pic in my offline database somewhere 😉

I'll go have a look...

Tetrium wrote:

Shorting 2 of these pins while setting motherboard jumpers (1 shorted one way, one the other) sounds risky, wouldn't that cause a short?

I'm not sure. However, I would like to try and short BF0 (Y33) and BF1 (X34), and test this. Do you know how I can short these two pins? Do I connect these two pins using a very small piece of metal? Also, do I place this small metal piece on the "top side" of the CPU. When I say "top side", I mean the face of the CPU which has the heatspreader on it. Not the pins side. Finally, I don't have a soldering iron. As a temporary idea, could I hold this piece of metal in place using a tiny drop of glue? (However, it might melt because of the heat!)

I'd use some silverpaint/conductive paint

I uploaded the pic, but it seems theres 2 other pins connected. I'm not sure which ones and what this pinmod does. I'll need to look in the chart which pins they are

Edit: Are these AJ23 and AJ21?

Tetrium wrote:

I uploaded the pic, but it seems theres 2 other pins connected. I'm not sure which ones and what this pinmod does. I'll need to look in the chart which pins they are

Edit: Are these AJ23 and AJ21?

Interesting. Looking at the pin out diagram, I believe these are pins Y33 and W33. I don't know what this pin mod does.

Tetrium wrote:

I'd use some silverpaint/conductive paint

I have a tiny bottle of this stuff somewhere. If I shake the bottle, the liquid goes cloudy. I wonder what tool I could use, to apply a thin line of this paint?

retro games 100 wrote:

Interesting. Looking at the pin out diagram, I believe these are pins Y33 and W33. I don't know what this pin mod does.

Don't forget the pin diagram is shown with the pins pointing up, so you need to mirror it if you compare it to the pic I posted 😉

Edit: I bought a bottle of the conductive stuff which came with a small brush.
I'd use some paper tape to cover all other pins except the 2 you want to short 😉

Tetrium wrote:

I uploaded the pic, but it seems theres 2 other pins connected. I'm not sure which ones and what this pinmod does. I'll need to look in the chart which pins they are

I've been thinking about this. I wonder what is the most likely purpose of that pin mod, as seen in your uploaded photo? I think that the most likely reason is to unlock the CPU, and in order to unlock it, you "disable" its default built-in multiplier. I wonder if this photo shows the correct pins to short, in order to unlock its default multiplier. It's possible I suppose, that the pins to short are Y33 and W33, and not Y33 and X34. However, pin W33 is labelled NC, which as you say is "not connected". Strange.

Tetrium wrote:

Don't forget the pin diagram is shown with the pins pointing up, so you need to mirror it if you compare it to the pic I posted 😉

Yep. 😀 I was careful when I checked this, but it would be worth someone else double-checking, because "two heads (four eyes?!) are better than one" 😉

Tetrium wrote:

I'd use some paper tape to cover all other pins except the 2 you want to short 😉

Thanks for the tip. I have a roll of decorators masking tape. I'll use that...

Lol! I finally found some more info on the net about this pin mod!
http://www.vintage-computer.com/vcforum/showt … 3702#post153702
The funny thing is, I already posted in that thread myself(!) and forgot(!!) that I did!

Good morning Tetrium! Coffee? Yes please! 😁

Edit:Thinking about it, it may be possible it won't be possible to get the desktop variants over 3.5x. Still I'm willing to try it out since I got 9 233mmx chips coming my way.
Man...why do I keep buying the stuff, 🤣!
Otoh, they were only €0.80 the piece, life long stock man! Life long stock! 😁
🤣

9 CPUs? 🤣 You're worse then me! 😉

The really interesting information seems to be on page 3: http://www.vintage-computer.com/vcforum/showt … 7-systems/page3

User @Neon_WA says: "as you can see from the table, the BF0 & BF1 pins set what the chip will try to boot at". He then includes 3 .jpg links. The images shown in these links indicate that the two relevant pins are BF0 and "NC" (pin W33). I wonder, do I short these two pins, or do I short BF0 and BF1 (pin X34).

I tried a quick test. I broke off a tiny piece of metal, from a staple. I then sellotaped this piece to pins BF0 and BF1. I made sure the system worked OK, by setting the board's jumpers to 66 FSB / 3.5 multi. The system POSTed OK, and reported the P233 CPU as 233 MHz.

I then adjusted the mobo's jumpers, and set the multi to 4. I left the FSB unchanged at 66. In theory, the POST screen should say 266 MHz. Unfortunately, the POST screen reported the CPU speed as 133 MHz.

This quick test has failed, and it may have failed because the small piece of metal is not making the correct contact with the pins. It is also possible that the contact is OK, but I have selected the wrong pins to short. Perhaps I need to short BF0 and that other "NC" pin?

retro games 100 wrote:

I tried a quick test. I broke off a tiny piece of metal, from a staple. I then sellotaped this piece to pins BF0 and BF1. I made sure the system worked OK, by setting the board's jumpers to 66 FSB / 3.5 multi. The system POSTed OK, and reported the P233 CPU as 233 MHz.

I then adjusted the mobo's jumpers, and set the multi to 4. I left the FSB unchanged at 66. In theory, the POST screen should say 266 MHz. Unfortunately, the POST screen reported the CPU speed as 133 MHz.

This quick test has failed, and it may have failed because the small piece of metal is not making the correct contact with the pins. It is also possible that the contact is OK, but I have selected the wrong pins to short. Perhaps I need to short BF0 and that other "NC" pin?

I went through this a few years ago with the exact same results. Burned several hours before I finally gave up.

I tried this trick on my Abit TX5, Shuttle HOT-569 and a Chaintech 5TDM2 with no results. 🙁

Oops. I tried the silver paint method, with bad results. I used decorater's masking tape, and sectioned off the area which needed to be painted on the surface of the CPU. I decided to paint between pins BF0 and BF1. I applied this area with silver paint using a thin paint brush, and noticed that the area wasn't turning silver colour. So I applied more and more and more. After 6 dabs with a loaded paint brush, I still couldn't see a line of silver between these two pins. I removed the masking tape, and all of the paint had leaked underneath it, shorting about 10 of the CPU pins!

You'd be better off dabbing a toothpick into the paint, and using it like a pen to draw the line on. As you've seen, other methods can be a bit... frustrating.

Actually, I'm sure I've tried something like that in the past. (Toothpick method.) I seem to remember that not much paint was sticking to the toothpick, and then being transfered to the area which needed painting. I've just had a browse on ebay, and something called a conductive pen exists. That might be an idea. The only practical problem is that they're not really cheap.

The problem with conductive pens is that most of 'em have too wide a tip to work for the tiny lines needed on CPU pinmods. You can mask off the area, but you'll still run into the same bleeding problem as you did with a brush.

Edit: Actually, there's also the other method...bridge the socket itself with a little U-shaped piece of wire...either really fine gauge magnet wire, or a single strand of stranded wire would work, you just need it thin enough not to interfere with the seating of the CPU. That method really only works when the pins to be bridged are adjacent to each other, but luckily in this case, they are.

Yep, I need to try the "wire method". 😀 Earlier today, I put a shard of staple inside one of the CPU socket pin holes, but naturally the CPU pin(s) itself had no chance to sit down flat inside the CPU socket area, because the shard of staple was much too fat to allow the CPU pin to sit immediately alongside it. I'll go and buy some wire.. Thanks!

Old Thrashbarg wrote:

Edit: Actually, there's also the other method...bridge the socket itself with a little U-shaped piece of wire...either really fine gauge magnet wire, or a single strand of stranded wire would work, you just need it thin enough not to interfere with the seating of the CPU. That method really only works when the pins to be bridged are adjacent to each other, but luckily in this case, they are.

That's the method I used. I stripped the paper off a twisty tie.