sofakng wrote on 2022-10-09, 17:20:

I've been donated two different machines: […]
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I've been donated two different machines:

IBM Personal Computer 300PL - Pentium III 500 MHz
and
IBM Personal Computer 350 - Pentium MMX200 MHz (*uses Pentium 200 MHz MMX overdrive chip because this motherboard doesn't support MMX chip voltage)

I'm trying to build the "do-it-all" machine covering games from as early as possible up to Quake, but focusing more on early 486-era DOS games.

Is there any reason to NOT use the faster P3-500 machine? If I understand correctly, speed sensitive games will also have trouble on the P1-200?

Can anybody give me any recommendations or suggestions?

I use a Pentium 3 1400MHz Tualatin as an all-in-one setup of sorts. Disabling L1 and L2 caches is enough to let me play even notoriously speed sensitive games like Gateway .

My fear is that a Pentium 3 at 500MHz with caches disabled might actually become too slow for 486 era DOS stuff. There are also various slowdown utilities available . I have not needed to use one, so I can't personally comment, but I have read that though may work flawlessly in some cases, they may introduce (or not correct) issues in some cases .

If the Pentium 3 board support Cyrix/VIA CPUs, you might consider one of these as they reputedly offer great, granular and very compatible slowdown options . There have been discussions about these on Vogons .

EDIT : See also Re: I need help with picking a psu for my Pentium 3 build?

How many ISA slots do the systems have? For a 'do it all' DOS machine you generally want multiple ISA sound options. If they both have at least three, you should be good regardless. If the P200MMX has significantly more, it might be the better choice.

Use DosBox-X for speed sensitive games that won't run on PIII 500. Upgrade CPU to PIII 600 Katmai or PIII 900 Coppermine if the motherboard supports it. This rig could cover the whole DOS era + Windows 98 until 2001.

Sell Pentium MMX200 MHz and use the money to buy parts for PIII. Speed sensitive DOS games will run too fast on it anyway and it's too slow for Windows 98.

AlexZ wrote on 2022-10-09, 18:42:

Sell Pentium MMX200 MHz and use the money to buy parts for PIII. Speed sensitive DOS games will run too fast on it anyway and it's too slow for Windows 98.

Depends on how speed sensitive the game is. A Pentium MMX can easily be slowed down to 486 and 386 speeds using SetMul for toggling the test registers and/or by disabling L1 and L2 cache. Phil has a page summarizing this.

But if we're talking 80s era DOS games, which potentially need something slower than a 386, then it might be better to look for other options.

OP mentioned early 486 eraas starting point, so 1990 at earliest and Quake as cut-off, so mid to late 90s at latest.

If the P3 is a 500EB, there is more latitude for adjustment of FSB, but even going from 500 to 250MHz won't be slow enough and disabling L1 cache will likely be too slow (doing that on my 1400MHz P3 brings me to fast 386/slow 486 land, so on a 500MHz, it would be too slow).

ISA slots are a good point, but might not be essential if the motgerboard has DDMA support, in which case a highly compatible PCI sound card (ALS4000 or YMF7x4) might suffice .

darry wrote on 2022-10-09, 19:07:

If the P3 is a 500EB, there is more latitude for adjustment of FSB, but even going from 500 to 250MHz won't be slow enough and disabling L1 cache will likely be too slow (doing that on my 1400MHz P3 brings me to fast 386/slow 486 land, so on a 500MHz, it would be too slow).

On my system disabling L1 slows a 650MHz P3 to around 386/33MHz, so it wouldn't be much different apparently.

But that is too slow for a lot of games so a tool like throttle is needed to adjust speed for speed sensitive games, which is a hit and miss. Some games are perfectly fine with it, some have minor issues you might not even notice and some are rendered completely unplayable. The 200MHz pentium mmx probably is more compatible as changing speed through registers, as far as I know, has no ill side effects.

Sombrero wrote on 2022-10-09, 19:30:

darry wrote on 2022-10-09, 19:07:

If the P3 is a 500EB, there is more latitude for adjustment of FSB, but even going from 500 to 250MHz won't be slow enough and disabling L1 cache will likely be too slow (doing that on my 1400MHz P3 brings me to fast 386/slow 486 land, so on a 500MHz, it would be too slow).

On my system disabling L1 slows a 650MHz P3 to around 386/33MHz, so it wouldn't be much different apparently.

But that is too slow for a lot of games so a tool like throttle is needed to adjust speed for speed sensitive games, which is a hit and miss. Some games are perfectly fine with it, some have minor issues you might not even notice and some are rendered completely unplayable. The 200MHz pentium mmx probably is more compatible as changing speed through registers, as far as I know, has no ill side effects.

Good point about performance to clock ratio not being even close to varying linearly with caches disabled, because FSB then becomes the great equalizing bottleneck. Thanks for correcting me on that.

Early games aren’t throttled but pentium 200 is probably already too fast for those.

There is a lot that a p3 500 can do.

Not much that a 200 can do that it can’t (other than being cooler. 😉

Sphere478 wrote on 2022-10-09, 20:18:

Early games aren’t throttled but pentoum 200 is probably already too fast for those.

There is a lot that a p3 500 can do.

Not much that a 200 can do that it can’t (other than being cooler. 😉

Disagree. Katmai has a massive performance gap when disabling caches. Games like Commanche and U7 really need tuning capability in the 486 range and a P3 won't deliver it.

S370 and Slot1 motherboards get much more versatility with C3 cpus on board.

Win95 and Turbo Pascal games, off the top of my head

Joseph_Joestar wrote on 2022-10-09, 18:56:

Depends on how speed sensitive the game is. A Pentium MMX can easily be slowed down to 486 and 386 speeds using SetMul for toggling the test registers and/or by disabling L1 and L2 cache. Phil has a page summarizing this.

Will it be able to toggle all the registers and caches being an Overdrive? I expect the multiplier being locked at least?

gdjacobs wrote on 2022-10-10, 02:49:

Sphere478 wrote on 2022-10-09, 20:18:

Early games aren’t throttled but pentoum 200 is probably already too fast for those.

There is a lot that a p3 500 can do.

Not much that a 200 can do that it can’t (other than being cooler. 😉

Disagree. Katmai has a massive performance gap when disabling caches. Games like Commanche and U7 really need tuning capability in the 486 range and a P3 won't deliver it.

S370 and Slot1 motherboards get much more versatility with C3 cpus on board.

I think we tried to say the same thing but you misinterpreted me.

H3nrik V! wrote on 2022-10-10, 04:20:

Joseph_Joestar wrote on 2022-10-09, 18:56:

Depends on how speed sensitive the game is. A Pentium MMX can easily be slowed down to 486 and 386 speeds using SetMul for toggling the test registers and/or by disabling L1 and L2 cache. Phil has a page summarizing this.

Will it be able to toggle all the registers and caches being an Overdrive? I expect the multiplier being locked at least?

You basically have a pentium mmx there. But you will set the voltage to 3.3v and you can not change the multiplier or use it as a secondary cpu in smp. As a primary will work though. Several of the pins relating to those functions appear to have not been connected to gold wires. These are the only real differences that I have come across with the overdrive.

Re: Socket 5 / 7 Pentium Overdrives. Higher Multipliers? SMP? Let’s find out..

H3nrik V! wrote on 2022-10-10, 04:20:

Will it be able to toggle all the registers and caches being an Overdrive? I expect the multiplier being locked at least?

Oh, I just realized that it's an overdrive. Not sure about all the test registers in that case. Furthermore, if it's an OEM system, it should be checked if the BIOS allows disabling the L1 and L2 cache.

The multiplier is less of an issue as it's possible to reach a wide range of speeds even without adjusting that, assuming everything else works.

Joseph_Joestar wrote on 2022-10-10, 05:30:

Oh, I just realized that it's an overdrive. Not sure about all the test registers in that case.

Clueless1 has (or had) a P55 based POD. Full TR12 register support.

Sphere478 wrote on 2022-10-10, 04:31:

I think we tried to say the same thing but you misinterpreted me.

Definitely possible.

In general, I've found PMMX CPUs to be capable of a high degree of performance tuning, able to hit targets from full speed all the way down to high 386SX/low 386DX speeds. A P3 will have much higher top end performance, but it's almost impossible to achieve performance targets between slow to middling 386 and what you get with your best FSB underclock. This is a consistent experience with others as well.
Re: Let's benchmark our systems with caches disabled

leileilol wrote on 2022-10-10, 03:18:

Win95 and Turbo Pascal games, off the top of my head

Yes, right, I remember this issue, too ! 🙂
It was so famous that HEX editors like XVI32 have a TP7 patching menu, I remember.

Patch BORLAND PASCAL 7.0 EXE files for execution on processors > 200 MHz

Source: http://www.chmaas.handshake.de/delphi/freewar … 32.htm#features

sofakng wrote on 2022-10-09, 17:20:

I've been donated two different machines: […]
Show full quote

I've been donated two different machines:

IBM Personal Computer 300PL - Pentium III 500 MHz
and
IBM Personal Computer 350 - Pentium MMX200 MHz (*uses Pentium 200 MHz MMX overdrive chip because this motherboard doesn't support MMX chip voltage)

I'm trying to build the "do-it-all" machine covering games from as early as possible up to Quake, but focusing more on early 486-era DOS games.

Is there any reason to NOT use the faster P3-500 machine? If I understand correctly, speed sensitive games will also have trouble on the P1-200?

Can anybody give me any recommendations or suggestions?

if i was given those two then, depending on motherboard etc, i'd use the 200 as the win95/DOS machine for all the DOS games and applications with a bit of win95 too while the P3-500 would get win98 and a modest 3d card if possible and be the go to for all kinds of late 90's and circa 2000 windows 3d games

but the p3-500 would likely be just as good as the do-it-all machine excepting perhaps a few quirky dos games that are just as likely to be quirky on the 200.

as other said, it depends on isa lots and other hardware

My suggestion of giving preference to PIII 500 comes from the opening post requesting a "do-it-all" machine for games up to Quake, but focusing more 486-era DOS games. Other similar games such as Duke Nukem 3D, Blood, Shadow Warrior run poorly on P200MMX in SVGA graphics. You do not get the frame rate you are used to with modern hardware. 486 era games are protected mode games that often work fine on PIII. It is older 286-386 games that are much more troublesome. If locked multiplier is a problem and DOS games is the main focus of the rig then the CPU could be swapped for a slower unlocked PII Deschutes/Klamath 333 that can be further slowed down.