VOGONS


First post, by BitWrangler

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Howdy folks,

So bit of discussion going on in another thread about how flexible or not P4 systems are for speed control. I thought we could bring those insights in from there and add to them for a comprehensive "Everything you can do to get retro working well on P4". Reasons.. older stuff is getting ever more expensive, the P4 was the last intel class "in touch" with DOS/Win9x in general. Which implies yes there are specific examples of Core2 and later industrial machines with legacy features, but generally all that was left behind.

To get it all out of the way, K6 2/3 plus, Via C3, Mobile XP, Mobile Barton are all much superior solutions to highly adjustable retro systems, there are threads about them, this thread is about Pentium 4 class, including Celeron for the same sockets.

Still... Y tho' ? Because P4 prices are looking like making a move, this is maybe last chance for curbfind/free/$10 in local listings systems that might have a chance of being acceptable retro rigs . If you're reading this in a couple of years, I hope they're still among least expensive. Why do *I* care? Bending the boundaries, and I kinda have an urge to whittle everything down to "I can cope with it" rigs, while I can compare them to the genuine thing, before I divest myself of the hoard of real stuff.

Briefly, P4 class spanned socket 423, 478 and 775...

  • 423 was first, Willamette core P4s, 400 FSB, SDRAM or RDRAM, AGP possibly 2x/4x, ISA slots common, slow... possibly too slow for golden era 486 with extreme kneecapping. Machines of this class may best be native late Windows 98 gamers, 98 drivers should exist for most contemporary hardware. Can dip a toe in early XP stuff, but run out of steam early. DOSbox capable, but might not manage fast 486/pentium speed.
  • 478 next, Northwood and Prescott cores, 400/533/800 FSB some SDRAM, mostly DDR, AGP 4x/8x mainly, boards with ISA slots available.. may offer about the best DOS speed variability, given 3ghz plus 800Mhz FSB... should have a lot of win98 support, suitable as late/fast 98 gamer, early XP gamer, will run DOSbox nicely under windows, should run cycle accurate MAME cores for XTs, Tandys.
  • 775 the final P4 platform, Northwood, Prescot, Cedar Mill cores extending to Core2 Conroe and up 533/800(/1066/1333/1600) FSBs (Not P4 official) DDR and DDR2, AGP 4/8x and PCIe 8x or 16x for graphics, ISA slots hard to find, some late boards may not have 32 bit PCI... some win98 support but coverage getting patchy, could be a late/fast 98 gamer, slightly longer spell of early XP gaming for faster cores... probably only 2 low DOS speeds. Will run DOSbox nicely under windows, should run cycle accurate MAME cores for XTs, Tandys.

But that needs fleshing out. Following are the postings that inspired the thread, however, input is sought on all aspects, other slowdown utils and methods, which onboard/PCI audio chipsets have DOS functionality, which GPUs in AGP and PCIe, links to relevant threads good.

pixel_workbench wrote on 2022-01-20, 04:31:
This is not completely accurate. The reason it appears so is because using "SETMUL L1D" on a P4 actually disables the L2 cache, […]
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bloodem wrote on 2022-01-15, 10:31:

P4 is terrible when it comes to speed flexibility. There's no way of reaching 386 / 486 speeds, because even when disabling the L1 cache, the Netburst architecture is still too fast.

This is not completely accurate. The reason it appears so is because using "SETMUL L1D" on a P4 actually disables the L2 cache, and not the L1. I tested this on a board that can disable caches in BIOS, and then the P4 slows down to a level of a slow 486. Looking at the memory test graph in Speedsys supports this theory. Below are some DOS benches from my testing.

P4 2.8 Northwood 400MHz FSB, Soyo P4I845PE, 512MB DDR-266, Radeon 9550

Normal:
3dbench1.0c = 460.6
PCPbench = 406.1
Doom fps = 121.45

Using SETMUL L1D:
3dbench1.0c = 333.5
PCPbench = 132.1
Doom fps = 84.78

L1 & L2 caches disabled in BIOS:
3dbench1.0c = 21.5
PCPbench = 6.6
Doom fps = 10.36
bloodem wrote on 2022-01-20, 06:48:
Awesome find, pixel_workbench! True, I was disabling the L1 cache with setmul, because none of the socket 478 boards that I test […]
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pixel_workbench wrote on 2022-01-20, 04:31:

This is not completely accurate. The reason it appears so is because using "SETMUL L1D" on a P4 actually disables the L2 cache, and not the L1. I tested this on a board that can disable caches in BIOS, and then the P4 slows down to a level of a slow 486. Looking at the memory test graph in Speedsys supports this theory. Below are some DOS benches from my testing.

Awesome find, pixel_workbench!
True, I was disabling the L1 cache with setmul, because none of the socket 478 boards that I tested had the BIOS option to do so.
Anyway, although that slow 486 speed is actually very nice for me (I've found that most/all of my favorite early DOS games work just fine at this speed), this doesn't really change the fact that, overall, P4 platforms are still far from being flexible.

BitWrangler wrote on 2022-01-20, 13:13:

Hmmm wonder what it's like with an 800 Mhz FSB P4 when you do L1 off, Pentium class? then maybe L1 off at 533 is 486 and at 400 is nearer 386 (bearing in mind multi lower on 800 chip, so at 400 it's at early willamette clock speeds, but IPC might be higher)

Though I guess I could scare up the P4M 1.8 I thought I had kicking round somewhere, and see how speedstep behaves.

Edit: reviewing my options of hardware to play around with this on, and I don't seem to have a "goldilocks" CPU or motherboard combo, stuff that's either too good or too bad. Too good mainly meaning I've got different plans for it already. In investigating whether a 331 Celerunt would take 200/800Mhz I found that there's an additional FSB step that might be available on some socket 775 boards. Intel specced a 166/667 FSB which they never released a desktop CPU for, but only used on mobile. However, it might have been implemented with correct PCI/AGP dividers in some boards/chipsets, because MFers never knew Intel wouldn't release 166/667 desktop CPUs. Taping over a pad is meant to enable it. Useful to make settings more granular, modular, interactive-odular. Or because it's a huge leap between 533 and 800 if you've got 533 CPUs. 533 to 800 is possible but you need a low multi (slow) 533 CPU that's practically perfect.

edit: formatting improvement

edit2: Getting a mention up here because being based on the same designs certain Xeons are arguably "Pentium 4 class hardware" and have a bonus, Xeons of this era are downward unlocked, you can set lower multipliers. So don't necessarily turn down a free/cheap Xeon, but don't necessarily lumber yourself with it either, check out expansion options, you might not want to deal with only one or two "normal" PCI slots and no AGP etc, you might not want to buy funky RAM cards or weird hard drives. Server class hardware is more likely to head into the weeds in those areas, workstation class might be more flexible (and less likely to be housed in something approximating a borg cube, or a large slice thereof.) ... a primer from the era on P4 Xeon possibilities... https://www.overclockers.com/forums/threads/t … -thread.329096/

Last edited by BitWrangler on 2022-01-22, 18:12. Edited 3 times in total.

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Reply 2 of 56, by mockingbird

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Seeing as how the multiplier-unlocked engineering samples and extreme editions are unobtanium, a VIA + P4 combination seems the best choice for CPU throttling.

With throttle, you get 16 different speed reduction options with VIA chipsets, plus the ability via switch to not toggle the L1 (so 32 combinations, actually), so setmul is of little value for the P4 compared to throttle.

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Reply 3 of 56, by pixel_workbench

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I think it's great if we can "correct the record" on the P4 and clear up some misconceptions. So far it appears that the BIOS option to disable caches no longer exists on many late P4 boards (Intel 865, 875 chipsets). It's more likely to appear on 845pe and earlier chipsets, and I have also seen that option on Sis 645 chipset boards.

Ultimately it would be great if we can get a software solution instead of depending on the BIOS.

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Reply 4 of 56, by BitWrangler

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Throttle http://www.oldskool.org/pc/throttle/DOS/ looks very useful, which we have some notes on around the forums, like Throttle Dos but searching throttle.exe will bring up more.

Then also we have some other utilities which may be of benefit... CPU Tuning, Throttling

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Reply 5 of 56, by Kahenraz

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BitWrangler wrote on 2022-01-20, 16:35:

423 was first, Willamette core P4s, 400 FSB, SDRAM or RDRAM, AGP possibly 2x/4x, ISA slots common, slow... possibly too slow for golden era 486 with extreme kneecapping. Machines of this class may best be native late Windows 98 gamers, 98 drivers should exist for most contemporary hardware. Can dip a toe in early XP stuff, but run out of steam early.

I bought a Pentium 4 1.4 GHz Willamette with 256MB of RDRAM and Windows ME back in the day and I can confirm all of what you said to be spot on from first hand experience. I used it for years up through and including Windows XP.

The computer came with Windows ME but I installed Windows 98se on it later and remember it being a speed demon that could run anything and everything. Windows 2000 felt a little slower but the stability made up for it. Windows XP was tolerable for many tasks but by this time I was bottlenecked by the amount of free memory available after the operating system had finished booting.

I'm certain now that the problems I experienced later were a result of not having enough memory for Windows XP which led to copious amounts of swapping. Even all of those years later, RDRAM was still very expensive and had to be installed in pairs so I ended up replacing the entire computer instead of upgrading further.

At some point I did replace the CPU with a 1.8 Ghz but there was no perceivable performance uplift.

Last edited by Kahenraz on 2022-01-20, 23:55. Edited 1 time in total.

Reply 7 of 56, by BitWrangler

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Well it becomes a more interesting problem sure, but not the overdramatic hyperbole I've heard here before "With only PCI you're completely cut off from DOS !!!111" but it's looking like P4s might not go as slow as such ultra finicky games require anyway so SB emulation support by TSR on PCI cards would be acceptable for much of the late 486 stuff and the outliers can be DOSboxed.

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Reply 8 of 56, by BitWrangler

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Non-ISA solutions suggested here should also be applicable to P4 systems without ISA... PCI or PCI Express Sound Card for DOS Sound Blaster Sound Effects working on Intel Sandy Bridge Z68 or newer chipsets

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Reply 9 of 56, by TrashPanda

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Out of curiosity, I recently bought a ram lot that has 4 identical 128mb Rdimms in the lot, I know its slow ram but I wouldnt mind owning a P4 build with it, does 478 support Rdimms or were they limited to 370 and 423 ?

512mb of Rdimm ram would put it squarely in win98se territory and with a few utils and a slow P4 would likely make for a nice top end DOS box too, IIRC 423 had sata support ..I didnt use 423 much at all back in the day so I may be miss remembering this.

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Reply 10 of 56, by Joakim

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Ok, I've never tested it myself, cool I thought you more or less were stuck with command prompt but there seem to be some 'emulation' going on with some sound cards. Only a few of them can do this however, and they are more or less needed for this kind of setup I guess.

I think you are right about speed sensitive games being being problematic in multiple areas so possibly these games are maybe not that relevant.

Last edited by Joakim on 2022-01-21, 06:43. Edited 1 time in total.

Reply 11 of 56, by TrashPanda

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Seems I was wrong about sata support and 423 boards, even 478 didn't get Sata support till late in its cycle, and finding a board with ISA+RDRAM+Sata support is impossible, I found one industrial 478 board with everything but it dropped AGP and well the board is useless without AGP.

ISA+RDRAM+AGP is easy to find so I may go that route and grab a PCI Sata card with Sata II support.

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Reply 12 of 56, by mothergoose729

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Great thread, I love the p4 for windows 98, if a reliable way to disable L1 cache is found it can go a long way for DOS. The most important speed range for DOS is the 386 and the slower pentiums. Both should be possible with throttle.

I think a lot more can be said for using PCI sound cards for DOS as well. It's a topic rarely covered in the community.

Reply 13 of 56, by leileilol

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BitWrangler wrote on 2022-01-20, 18:03:

Throttle looks very useful,

It's nice but going throttle beyond 6 brings very uneven latent stuttery slowdowns, at least on my P4s. 6 however seems to be a 'rough 6th generation PC speed' which is suitable for 1998-99 stuff I guess 😉

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Reply 14 of 56, by TrashPanda

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leileilol wrote on 2022-01-21, 07:30:
BitWrangler wrote on 2022-01-20, 18:03:

Throttle looks very useful,

It's nice but going throttle beyond 6 brings very uneven latent stuttery slowdowns, at least on my P4s. 6 however seems to be a 'rough 6th generation PC speed' which is suitable for 1998-99 stuff I guess 😉

I mean if you really need to go slower then there is always DOSBox which for Pre early Pentium and socket 7 speeds is more than capable and I dont think trying to get a P4 down to that kind of speed is worth the effort or frustration.

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Reply 16 of 56, by TrashPanda

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leileilol wrote on 2022-01-21, 15:24:

If I wanted to emulate though, i'd do it on my main computer...

Also there's things that DOSBox can't reach, like overscan, serial devices and using the pc speaker 😁

Yup I know, but .. making a P4 try and run at sub 500Mhz (even 500 Mhz is likely not a great experience) is kind of asking for a bit much of any tool, so unless you actually have said Pentium MMX/Amd alt or 486/386/286/8086 then ..then DOSBox is your only real alternative, I guess you could always deal with the stutter. (A P4 willamette 1.3/1.4 might be able to get down to sub 500 without stuttering, I dont have one to test 🙁 .....yet)

I'm not an advocate for DOSBox since I dont like it for most uses but even I realise that it has its niche uses where it works really well and is perfect for filling in gaps in early DOS hardware you dont have yet.

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Reply 17 of 56, by BitWrangler

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Yah, I see it differently, using it as "caulk" filling a few gaps, rather than "May as well run everything on DOSbox" ... it runs on 9x too Can you run DOSBox in Windows 98 (NOT run Win98 in DOSbox!)
So you can get your fast win 98 system set up with gameport supported and have your gameport sticks and pads working in DOSbox games, which you may not be able to do on a modern modern system. Also, although PS/2 ports made something of a comeback, there was a dry spell between P4 and 5 or 6 years ago, so may be more convenient for using favored keyboards and mice. (Even with the comeback, you might have ended up with a modern system without them, they're not universal any more)

So those would be reasons where you might find a P4 better to have DOSbox on than a modern system, for 486 and earlier at least. You'd have your classic input devices plugged in and ready to go for fast DOS native, Win98 native, and DOSbox slow DOS gaming all on the same system. Maybe your 19" FST CRT also.

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Reply 18 of 56, by TrashPanda

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BitWrangler wrote on 2022-01-21, 16:40:

Yah, I see it differently, using it as "caulk" filling a few gaps, rather than "May as well run everything on DOSbox" ... it runs on 9x too Can you run DOSBox in Windows 98 (NOT run Win98 in DOSbox!)
So you can get your fast win 98 system set up with gameport supported and have your gameport sticks and pads working in DOSbox games, which you may not be able to do on a modern modern system. Also, although PS/2 ports made something of a comeback, there was a dry spell between P4 and 5 or 6 years ago, so may be more convenient for using favored keyboards and mice. (Even with the comeback, you might have ended up with a modern system without them, they're not universal any more)

So those would be reasons where you might find a P4 better to have DOSbox on than a modern system, for 486 and earlier at least. You'd have your classic input devices plugged in and ready to go for fast DOS native, Win98 native, and DOSbox slow DOS gaming all on the same system. Maybe your 19" FST CRT also.

Ive always seen it as a tool and I tend to use it as one, using it to fill in a few gaps here and there till I can replace DOSBox with physical hardware, some people treat it as the entire garage and a fleet of mechanics and get upset when they try to use it beyond what it was designed for .. like trying to run windows 95/98 on it or expecting it to emulate IDE/SCSI devices.

Personally if I can avoid using DOSBox I will, its emulation while good has a few quirks that I dont like and honestly running DOS via emulation on a modern PC just feels plain odd to me.

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Reply 19 of 56, by The Serpent Rider

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I found one industrial 478 board with everything but it dropped AGP and well the board is useless without AGP.

There are some industrial 865G boards with ISA, which have fully functional AGP. And probably a couple of LGA775/865G/ISA boards with official Core 2 support. Good luck finding them though.

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