How can I slow down a modern or pentium 2 pc to 386/486 levels?

[invictius]

I have everything else - crt monitor, windows 98, sound blaster 16... but can't find a 386 or 486 anywhere. I want to experience whatever slowdown happened in iwads on a dx40 and see how demanding eternal doom was. Haven't had much success with dosbox.

EDIT: would an 8-bit isa video card cripple a p2-350 is suitably?

[AndrewB]

You might try finding a compatible CPU slowdown utility, and I'm pulling numbers out of my butt here, but occupy 80-90% of CPU to simulate a 486, and 95% of CPU for a 386.

[invictius]

AndrewB said:

You might try finding a compatible CPU slowdown utility, and I'm pulling numbers out of my butt here, but occupy 80-90% of CPU to simulate a 486, and 95% of CPU for a 386.

Which cpu are those figures for?

[AndrewB]

I was thinking about 80% for a 486 133MHz, 90% for a 486 66MHz, and 95% for 386 33MHz. But like I said, my butt.

[invictius]

AndrewB said:

I was thinking about 80% for a 486 133MHz, 90% for a 486 66MHz, and 95% for 386 33MHz. But like I said, my butt.

Oh, I meant which host cpu, unless those figures work on any cpu. I edited the p2 350 in to my question after so I wasn't sure if you were referring to that.

[AndrewB]

Well yeah, I was basing that off the P2 350. If you're talking about something modern then I don't know if it's even possible to simulate a 486 using a CPU grabber.

[invictius]

AndrewB said:

Well yeah, I was basing that off the P2 350. If you're talking about something modern then I don't know if it's even possible to simulate a 486 using a CPU grabber.

What are your estimates for a p3-700? I can underclock it to 266 at 66mhz bus, I'm guessing that would run roughly as fast as a p2 350.

[AndrewB]

I've already told you more than I know.

[Buckshot]

Thought you could set compatibility/throttle modes in DOSbox settings to gimp processors speeds and extensions down to legacy cpu emulation?

Hmmmm. Maybe not.

[Remilia Scarlet]

Yeah, DOSBox can do that. In the config file, there's a section to define how DOSBox emulates the CPU and how fast it can run. You can also change the number of CPU cycles (the "speed" roughly) while it's running with control and one of the function keys.

Or, remove the heatsink. It'll slow down in no time.

(don't actually remove your heatsink...)

[invictius]

yukib1t said:

Yeah, DOSBox can do that. In the config file, there's a section to define how DOSBox emulates the CPU and how fast it can run. You can also change the number of CPU cycles (the "speed" roughly) while it's running with control and one of the function keys.

Or, remove the heatsink. It'll slow down in no time.

(don't actually remove your heatsink...)

I first saw that vid when it was released, the guy downloaded it along with several vids of just fans spinning...

I ran a benchmark under dosbox which matched the cpu I specified in config, but when I run vanilla it no longer shows the number of cycles, just percentage of cpu power. It definitely isn't running at 386 speed.

[Ashstrodamus]

I still have my old Pentium 3. It's for sale too. Only 3 million dollars!

[Remilia Scarlet]

invictius said:

I first saw that vid when it was released, the guy downloaded it along with several vids of just fans spinning...

I ran a benchmark under dosbox which matched the cpu I specified in config, but when I run vanilla it no longer shows the number of cycles, just percentage of cpu power. It definitely isn't running at 386 speed.

I think DOSBox has an "auto" setting for the CPU cycles by default anymore that you have to explicitly disable. If something that uses a 32-bit extender, like Doom for example, starts running, DOSBox will switch over to the dynamic cycles mode or whatever.

I might be wrong, however. I haven't messed much with DOSBox for the past few months.

[invictius]

yukib1t said:

I think DOSBox has an "auto" setting for the CPU cycles by default anymore that you have to explicitly disable. If something that uses a 32-bit extender, like Doom for example, starts running, DOSBox will switch over to the dynamic cycles mode or whatever.

I might be wrong, however. I haven't messed much with DOSBox for the past few months.

Hmm, I can use that... I then use a benchmark tool that tells me to adjust dosbox's cycles until I get the cpu speed I want (386 dx40), which it displays. But in doom, there's menu and control lag, I'm sure this didn't happen on a real 386dx40.

[Quasar]

Here's how I'd go about it. Open up Firefox. Now, go to some place that still has Flash, like say, Homestar Runner. Now open up 150 tabs with Flash movies on them. OK that's a good step 1. Now, make sure you haven't updated your PC for a while so that wuausrv is visibly running in taskmgr and you are getting that god-forsaken "New updates are available" pop-up every 5 minutes. Great step 2. You should be at about 10% available CPU by now. For step 3, download and install cygwin and the source code for GCC and write a shell script which keeps recompiling it every time it finishes. This'll use up your hard drive bandwidth.