I've used Pentium MMX in the past to play some speed sensitive IBM 5150 games, pretty sure it ran fast enough 😀.

F2bnp wrote:

I've used Pentium MMX in the past to play some speed sensitive IBM 5150 games, pretty sure it ran fast enough 😀.

Used DOSBox 0.74? Official .exe or compiled by other? Default settings? Wich OS? Wich games?
Pentium MMX 200 MHz was expected to give 5 XT in dynamic mode, but gave in mentined benchmarks 10 times less by unknown reason. In real game - Doom - the performance was on close approximated level.

Would be fine if you tried your MMX machine in conditions of 16 bit testing there. And repeated conditions when the emulator works correctly.

Was quite a while ago, so I don't really remember the details. It probably wasn't 0.74, but rather 0.73. Default settings, Win98SE and I'm pretty sure I was fooling around with Paratrooper.
This was certainly on an MMX 233.

Recently installed DOSBox 0.74 on my Pentium 166 MMX/ Windows 95A PC:

Official version, not default settings (I'll have to get a copy of the config file to see what I changed). It runs, but performance is very bad - fps is all over the place (Only ran Duke Nukum and Duke Nukem II). Windows 95A was fully updated just before MS pulled the plug on Windows Updates around 2006.

As far as benchmarks, I won't run any. Someone else will have to do that.

JayCeeBee64 wrote:

As far as benchmarks, I won't run any.

It's not hard. You used Duke as benchmark already. Without them we will not know the concrete performance, while to have use it needs to be >=1 XT.
Your 166 MMX may give ~4 XT approximated from PII, - it's ~ 286 6 MHz. As default the emulator used 3000 cycles wich may to be too much for it and hence it may strugle because of it; 1300 cycles may be max for 166 MMX. You may set core=dynamic, cycles=1300 and then try Duke again, or set core=dynamic, cycles=315 and try XT games like Digger.

Doesn't matter, I just won't bother. This was only an experiment to see if DOSBox would run in my lowest spec retro PC, and it does. I'm not after optimal performance either.

As for XT games, I don't have them or want to play them (for now anyway). The oldest game I currently have and play is Crystal Caves, and I prefer to run it in my DOS 6.2 boot configuration anyway.

If you want to know the current specs of this PC, here they are:

Asus TX97-XE Socket 7 ATX Motherboard
Pentium 166MMX CPU
Generic Socket 7 CPU cooler
Generic 64MB EDO RAM (four 16MB 72-pin SIMM modules)
4.31Gb Western Digital & Seagate hard drives
Plextor PX-W2410A IDE CD-RW
Iomega ZIP-100 atapi drive
Generic 3.5 & 5.25 floppy drives
Creative Labs Graphics Blaster Riva TNT 16MB PCI video card
Diamond Monster 3D 4MB PCI (3dfx Voodoo Graphics)
Creative Labs Sound Blaster Pro 2 (CT1600) sound card
Gravis Ultrasound ACE (Version 1.0) sound card
Yamaha SW60XG MIDI card
StarTech 300-watt ATX power supply
Gravis Gamepad Pro (game port version)
Microsoft USB/PS2 mouse
Generic PS2 keyboard
Antec KS-288 Valueline Series ATX Mid-Tower case

JayCeeBee64 wrote:

Doesn't matter, I just won't bother.

It was known that it runs on Pentium MMX. The problem was what is minimum CPU where it runs with speed >= 1 XT. Your data above without concrete measures adds nothing.

As for XT games, I don't have them

They are easy to found with search engines.

Why would anyone do this when you can just run DOS games natively under Windows 95? 🤣

What you're doing is basically emulating a very old machine in a slightly less old machine.

Compatibility
Slower speed
Because we can

I think DOSBox should be capable of emulating a PC/XT before we can decide what the minimum CPU requirements will be 😀

3,5 years ago I did a video that shows running dosbox on a 386 system: https://www.youtube.com/watch?v=jeZIOZVLY0Q

Try running a game like Defender on a Pentium MMX. It is not going to happen no matter how you try to slow down the processor.

Yes, textmode CPU benches are one thing. Graphics/sound emulation puts a lot of extra stress on the emulator.

fischkopf11 wrote:

Why would anyone do this when you can just run DOS games natively under Windows 95?

XT booter games, emulation of some hardware, additional possibilities to solve compatibility issues.

Scali wrote:

before we can decide what the minimum CPU requirements will be

1 XT level is excepted to be emulated on 486 66-100 MHz. This needs to be checked.
If will not work in 0.74, may be works in previous 0.7x official versions (the suspicion for this was given by F2bnp).

elianda wrote:

3,5 years ago I did a video that shows running dosbox on a 386 system

This was cruelly. 😀
On 486 100 MHz you may make more practically interesting video. Preferably by that scheme (16 bit section) and then some XT games in the emulator.

Scali wrote:

Graphics/sound emulation puts a lot of extra stress on the emulator.

320x200 graphics modes emulation looks as not very demanding in DOSBox. As for sound - early games used speaker or allowed to run with it, may to be easy also. Needs practical checking on old CPUs.
On modern PCs if you set 315 cycles in DOSBox - you get 1 XT level in Speed Test. And with it you may run normally XT games in CGA and with speaker. Results in Doom (VGA, no sound) and Speed Test (text) have good correlation in DOSBox.
If the CPU supports higher emulation level in Speed Test, like 386DX, then in games for 286 you may try sound card emulation or a paththrough mode in some DOSBox builds. Needs practical checking.

Hint: for checking DOSBox gameplay is better to use CRT as LCD have lattencies themselves: up to 40 ms even on some TN (input lag + drawing).

Tertz wrote:

1 XT level is excepted to be emulated on 486 66-100 MHz. This needs to be checked.
If will not work in 0.74, may be works in previous 0.7x official versions (the suspicion for this was given by F2bnp).

Well, my point was that DOSBox doesn't fully emulate an XT yet. I bet the recent NTSC composite-compatibility patches have also changed the minimum requirements for emulating an XT, because they are more computationally expensive than the earlier, inaccurate emulation.
As DOSBox becomes more compatible with a real XT, it probably becomes slower.

Scali wrote:

my point was that DOSBox doesn't fully emulate an XT yet.

DOSBox is officially to play games only. If XT games run, it emulates XT.

I bet the recent NTSC composite-compatibility patches have also changed the minimum requirements for emulating an XT

If it's about SVN, not 0.74, then it's a little outside of the main interest.
While to bet about something is better to have facts, not a theory only. If there is a slowdown, it's important to know in what conditions and how much it is.

As DOSBox becomes more compatible with a real XT, it probably becomes slower.

DOSBox may become slower as there is less motivation to optimize code due to fast modern CPUs, compared to times when DOSBox development began. Same with most applications.

Pentium Pro 200 MHz - 4 XT in Speed Test. Pentium 200 should be faster, if not strange issues in 0.74

Tertz wrote:

If it's about SVN, not 0.74, then it's a little outside of the main interest.
While to bet about something is better to have facts, not a theory only. If there is a slowdown, it's important to know in what conditions and how much it is.

It is a fact that there is a slowdown.
Whether that actually significantly impacts the system requirements for XT games, I don't know.

Tertz wrote:

DOSBox may become slower as there is less motivation to optimize code due to fast modern CPUs, compared to times when DOSBox development began. Same with most applications.

My point is that DOSBox cuts a lot of corners, and doesn't emulate most things very accurately.
Doing more accurate emulation will be slower, even if you optimize it very well. There is simply more work involved.

Which brings me back to my original point more or less: How accurately does an XT have to be emulated? You need to set a certain standard first, then make your emulator actually reach that standard. Only then can you try and see what the minimum requirements are for that particular standard.
For me, 8088 MPH sets the standard for PC/XT-compatibility. If an emulator can run that, it should also run every PC/XT game out there properly (including all PC/XT-specific effects, such as the extra colours in CGA mode in California Games).
Since DOSBox cannot run 8088 MPH in the first place, system requirements do not apply.

Scali wrote:

It is a fact that there is a slowdown.

It's important how much and when.

system requirements do not apply

For games wich it runs without significant issues DOSBox fits requirements of emulation.