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-   -   Really slow machines? (https://www.mersenneforum.org/showthread.php?t=2949)

Doorbasher 2004-08-23 00:34

Really slow machines?
 
Hey evryone.

I have a few spare computers at home, and I like the idea of them doing something useful. Problem is, they might be too elderly to make a contribution, so I decided to check here first.

The first rig is a Pentium 60. I know that an 80586-class machine is powerful enough to do some factoring work, but there's a catch. I tested it, and it has the infamous bug in the floating-point divide instruction. (The FDIV bug). Now I don't want to turn in incorrect results. Is there a way to force the program to use an integer-based routine, or otherwise avoid the floating-point divide?

Next up is an 80486DX, running at 20 MHz. This one might have a problem with memory, it only has 5 MB at it's disposal. Enough power?

The final one, a 25 MHz 80486SX. No math coproscessor. This one runs on 12 MB I think, but I'm not sure how lack of an FPU will affect things.

I suppose my 8 MHz 80286 is beyond hope. :razz:

Anyhow, is it woth keeping these old rigs in service?

clowns789 2004-08-23 00:55

Perhaps you could go to Lone Mersenne Hunters and click on Operation Billion Digits. You won't get Primenet credit, but it's great for old computers.

xilman 2004-08-23 08:53

[QUOTE=Doorbasher]Hey evryone.

I have a few spare computers at home, and I like the idea of them doing something useful. Problem is, they might be too elderly to make a contribution, so I decided to check here first.

The first rig is a Pentium 60. I know that an 80586-class machine is powerful enough to do some factoring work, but there's a catch. I tested it, and it has the infamous bug in the floating-point divide instruction. (The FDIV bug). Now I don't want to turn in incorrect results. Is there a way to force the program to use an integer-based routine, or otherwise avoid the floating-point divide?

Next up is an 80486DX, running at 20 MHz. This one might have a problem with memory, it only has 5 MB at it's disposal. Enough power?

The final one, a 25 MHz 80486SX. No math coproscessor. This one runs on 12 MB I think, but I'm not sure how lack of an FPU will affect things.

I suppose my 8 MHz 80286 is beyond hope. :razz:

Anyhow, is it woth keeping these old rigs in service?[/QUOTE]
I keep a bunch of old machines in service though, not at the moment, anything quite as slow as a 486. Until about a year ago I had some DECStations running which were about as powerful as a 486DX2-66.

Anyway: all those machines can do something useful but you have to decide first whether you want to keep them powered up. Where I live has a miserable climate and so running fan heaters is fairly good idea most of the year. Getting computation from my heaters is a bonus.

What you may find difficult is using George's code to work on old systems because, as you point out, some of them don't have either enough memory and/or a working fpu. If you are prepared to download other software, UBASIC for instance, you can try factoring relatively small Mersenne numbers with ECM.


Paul

smh 2004-08-23 11:51

Doesn't GMP-ECM and the ecmnet client work on a 486?

I'm not sure if they're worth the electricity though.

Doorbasher 2004-08-23 14:41

Well, I'm a 17-year-old nerd that lives in his parents' basement. I've accumulated some 16 computers over the years, and my parents give me pretty much free reign over how much electricity I use.

I'm thinking that the 486DX just dosent have the memory, and the other one dosent have the FPU. The Pentium 60 is still possible though, but it has that bug. Does anyone know either of a workaround for it, or if Prime95 (or perhaps the factoring program they use in Operation Billion Digits) uses floating point? Even if it dosent I'm going to ty and get my dual Pentium 120s working on that project, once I can get it to see it's hard drives.

Pegaso 2004-08-23 22:18

Old is the wind and still blows
 
Nonsense. I have five 486 DX4/100, with 12 Mb running all the stuff of Msoft and they doing excellent job factoring. They ARE SLOW but they WORK Fine.
AAh, also have a 386 Rapidfire or something like that, and also do a decent job.
Regards
Carlos


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