Re: Need help building Pentium MMX VRM module (lots of information inside!) (re: IBM PC 330/350)

Posted on 2021-06-08, 17:10

by

by sofakng

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Thanks for the reply! Yeah, I'm sure it will be more complicated than it seems, right? Are you talking about the SENSE/DISABLE pins on the regulator module or something different? ...or are you talking about something on the motherboard to detect the regulator module and enable it? There doesn't …

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Need help building Pentium MMX VRM module (lots of information inside!) (re: IBM PC 330/350)

Posted on 2021-06-08, 14:28

by

by sofakng

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The IBM PC 330/350 models offered CPUs up to Pentium MMX 233 but they excluded the 2.8v VRM module unless it came with an MMX CPU. However, the pin headers are still present on the motherboard and the BIOS supports it without any issues. The IBM part number (FRU) is 76H3658 which corresponds to a …

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Re: Does this IBM PC 350 support Pentium MMX 233? (re: 200 MHz maximum speed?)

Posted on 2021-06-07, 15:51

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by sofakng

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Unless I'm missing something, this looks incredibly simple. I think all we need to know is the voltage regulator (U1) . I've contacted Semtech but I doubt they will get back to me. If we can figure it out, I would even be willing to design some PCBs and build a few for anybody that needs them.

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Re: Does this IBM PC 350 support Pentium MMX 233? (re: 200 MHz maximum speed?)

Posted on 2021-06-07, 01:11

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by sofakng

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

OK - So the IBM 76H3658 (VRM) seems to be the Semtech MP55C-3.3-2.8 VRM. Here is the datasheet. I'm not an electrical engineer (or even close!) but it seems quite possible to build a compatible adapter?

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Re: Does this IBM PC 350 support Pentium MMX 233? (re: 200 MHz maximum speed?)

Posted on 2021-06-06, 14:26

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by sofakng

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

It sounds like the MMX version of the IBML 330/350 was more rare (which makes sense because it would have been more expensive). I suppose I'll have to make a choice to use a slower chip (Pentium 166) which is also worse because it doesn't fully support SETMUL like the MMX chips do, or I can run the …

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Re: Does this IBM PC 350 support Pentium MMX 233? (re: 200 MHz maximum speed?)

Posted on 2021-06-05, 23:33

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by sofakng

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Thanks for the suggestion. The overdrive CPUs are extremely expensive. Do you think it’s possible to modify this motherboard for 2.8v maybe? EDIT: I can’t find any interposers either but that sounds interesting.

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Re: Does this IBM PC 350 support Pentium MMX 233? (re: 200 MHz maximum speed?)

Posted on 2021-06-05, 23:19

by

by sofakng

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

After doing a lot more research, I agree with your conclusion. It appears that you can often run 2.8v Pentium MMX CPUs for a short while but it's a bad idea and will eventually cause problems. I see you found the IBM FRU for that VRM (76H3658) but do you know what chip that was? It possible to …

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Re: Does this IBM PC 350 support Pentium MMX 233? (re: 200 MHz maximum speed?)

Posted on 2021-06-05, 20:24

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by sofakng

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Is there a way to confirm the motherboard CPU voltage? (ie. any DOS tools?) I would have not expected the system to POST let alone be stable (30+ consecutive runs of 3DBench2) at the higher single-supply voltage?

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Re: Does this IBM PC 350 support Pentium MMX 233? (re: 200 MHz maximum speed?)

Posted on 2021-06-05, 15:08

by

by sofakng

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Aww, you just ruined my day lol. You are probably right… I don’t have anything soldered at that spot either. I’ve also been having instances where the PC won’t POST but I didn’t extensively test with the non-MMX CPU. However I think it might related to the CMOS battery or ide/floppy cables. After it …

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Re: Does this IBM PC 350 support Pentium MMX 233? (re: 200 MHz maximum speed?)

Posted on 2021-06-04, 13:24

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by sofakng

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

In case anybody else is looking for information on this, I took a chance and tested the Pentium MMX 233 and it worked! However, the Wikipedia article is wrong about using the 75 MHz setting on the motherboard. You must use the 100 MHz setting for the correct speed. The BIOS will display the …

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Re: Recommended storage for IBM PC 350 (Pentium MMX 200/233) ?

Posted on 2021-06-03, 16:15

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by sofakng

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Here is my motherboard: Filename IMG_2789.jpg File size 1.76 MiB Views 409 views It looks like the one in the picture but I don't see any empty VRM pads? This post seems to suggest it supports it: My IBM PC 330 ...but I don't know the revision of the motherboard he was using.

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Re: Recommended storage for IBM PC 350 (Pentium MMX 200/233) ?

Posted on 2021-06-03, 16:01

by

by sofakng

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Thanks for the reply ... Yes, that's the same model I have. (IBM PC 350, 6587-90U) I think that article is referring to the Wikipedia article about the IBM PCs. It mentions these models coming with "up to" a Pentium 233 MMX. What spot on the motherboard are you referring to for the VRM? I have a …

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Re: Possible to expand S3 Trio64V+ on-board video memory? (re: motherboard)

Posted on 2021-06-03, 15:19

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by sofakng

in Marvin \ Video

in Marvin \ Video

Thanks so much for the help! This PC also came with a dedicated video card "Sigma Designs f/64" with a Weitek Power 9100 chip on it. I'm not sure the difference (benefit) of using that over the onboard Trio 64V+. Does anybody know about the Sigma Designs f/64 (Weitek Power 9100) and if I should use …

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Recommended storage for IBM PC 350 (Pentium MMX 200/233) ?

Posted on 2021-06-03, 15:15

by

by sofakng

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I've setting up my IBM PC 350 which has a Pentium 166 but I'm upgrading to a Pentium MMX 200 or 233. I purchased a Startech CF-to-IDE adapter to use with a spare Seagate ST1 2.5 GB but it's not working. I also tried using an IDE-to-USB adapter and it's acting strange so I think the CF card might be …

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Re: Possible to expand S3 Trio64V+ on-board video memory? (re: motherboard)

Posted on 2021-06-03, 01:28

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by sofakng

in Marvin \ Video

in Marvin \ Video

Thanks a bunch for the advice. It sounds like it's not worth looking into. Besides a 3D accelerator (ie. 3dfx Voodoo), are there any 2D cards that help with Duke3D or other software-only games? For example, will it be possible to play Duke 3D at 800x600 on a Pentium MMX 233? (with a "good" 2D card?)

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Possible to expand S3 Trio64V+ on-board video memory? (re: motherboard)

Posted on 2021-06-02, 20:07

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by sofakng

in Marvin \ Video

in Marvin \ Video

I'm looking at my IBM PC 350 which has an S3 Trio64V+ on the motherboard. However, there are two empty sockets above it: Filename IMG_2783.jpeg File size 763.67 KiB Views 1179 views Could I add more video memory? If so, where can I find memory chips and what kind? Also, is it even worth it?

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Does this IBM PC 350 support Pentium MMX 233? (re: 200 MHz maximum speed?)

Posted on 2021-06-02, 18:52

by

by sofakng

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I'm setting up an IBM PC 350 (model 6587-90U) This came with a Pentium 166 when I purchased (from a friend) but I'd like to install a Pentium MXX 233. According to Wikipedia this model came with up to a "Pentium MMX 233 with 75 MHz settings": Capture.PNG However, the case of the PC shows the jumper …

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Re: IBM 350 (Pentium 167 MHz) vs IBM 300 PL (P3 500 MHz) - Should I keep both?

Posted on 2021-05-29, 01:42

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by sofakng

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

How can I find out if I upgrade the IBM 350 to a Pentium 233 MMX CPU? The included CPU is labeled A80502166. The Wikipedia page for the IBM 350 says it included up to a Pentium 233 MMX?

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Re: IBM 350 (Pentium 167 MHz) vs IBM 300 PL (P3 500 MHz) - Should I keep both?

Posted on 2021-05-28, 21:26

by

by sofakng

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Thanks for the information! I think I can also use the 'setmul' utility, right? Does that mean I should just keep the faster Pentium 3 (slot 1) machine? (ie. is there no benefit to having the slower Pentium 1?)

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IBM 350 (Pentium 167 MHz) vs IBM 300 PL (P3 500 MHz) - Should I keep both?

Posted on 2021-05-28, 19:47

by

by sofakng

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I've just purchased some old hardware from a friend including the following: IBM 350 (Pentium 167 MHz, socket 7) IBM 300PL (Pentium 3 / 500 MHZ, slot 1) Is there a reason for me to keep both machines? I'd like to play as wide of a range of games as possible, but here are some notable games: Sierra …

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