Welcome to the Great Internet Mersenne Prime Search! To use this program you must agree to the terms and conditions, prize rules, etc. at http://mersenne.org/legal/ In case you ever forget, the GIMPS web site is at http://mersenne.org My email address is woltman@alum.mit.edu. For networking questions, contact Scott Kurowski at primenet@mersenne.org. FILE LIST --------- readme.txt This file. prime95.exe The program to factor and run Lucas-Lehmer tests on Mersenne numbers. whatsnew.txt A list of new features in prime95.exe. stress.txt A discussion of issues relating to stress testing a computer. undoc.txt A list of formerly undocumented and unsupported features. prime.txt A file containing your preferences. The menu choices and dialog boxes are used to change your preferences. local.txt Like prime.txt, this file contains more preferences. The reason there are two files is discussed later. worktodo.txt A list of exponents the program will be factoring and/or Lucas-Lehmer testing. results.txt Prime95.exe writes its results to this file. prime.log A text file listing all messages that have been sent to the PrimeNet server. prime.spl A binary file of messages that have not yet been sent to the PrimeNet server. pNNNNNNN & Intermediate files produced by prime95.exe to resume computation where it left off. eNNNNNNN Intermediate files produced during ECM factoring. fNNNNNNN Intermediate files produced during trial factoring. mNNNNNNN Intermediate files produced during P-1 factoring. WHAT IS THIS PROGRAM? --------------------- This program is used to find Mersenne Prime numbers. See http://www.utm.edu/research/primes/mersenne.shtml for a good description of Mersenne primes. Mersenne numbers can be proved composite (not prime) by either finding a factor or by running a Lucas-Lehmer primality test. INSTRUCTIONS ------------ There are two ways to use this program. The automatic way uses a central server, which we call the PrimeNet server, to get work to do and report your results. You do not need a permanent connection to the Internet. The second method is the manual method. It requires a little more work and monitoring. I recommend this for computers with no Internet access or with some kind of firewall problem that prevents the automatic method from working. If you are running this program at your place of employment, you must first GET PERMISSION from your network administrator, boss, or both. This is especially true if you are installing the software on several machines. Many companies have policies that prohibit running unauthorized software. Violating that policy could result in termination and/or prosecution. INSTRUCTIONS FOR THE AUTOMATIC METHOD ------------------------------------- 1) Download and unzip prime95.zip. You've probably done this already since you are reading this file. 2) Connect to the Internet. Create an account at http://mersenne.org 3) Run prime95.exe. You will see 4 dialog boxes: 3a) In the welcome dialog box, choose "Join GIMPS!". 3b) In the second dialog box, enter your user id and optional computer name. If you are using several computers, use the same user ID but a unique computer name on each machine. An easy-to-remember user ID will be helpful if you plan to visit the PrimeNet server's web page to view reports on your progress. 3c) In the third dialog box, fill in roughly how many hours a day you leave your computer running. Click OK. 3d) In the fourth dialog box, leave the "Use Primenet..." checkbox checked. Do not turn this checkbox off even if you disconnect from the Internet. Check the "Use a dial-up..." checkbox if you use a modem to connect to the Internet. Note that prime95 will not dial-up to connect to the Internet, rather it waits for a time when you are already connected to contact the server. Click OK. Prime95 will now contact the PrimeNet server to get some work for your computer to do. 4a) If a proxy server is the causing connection troubles, see the later section on "SETTING UP A PROXY SERVER". 4b) If the program will not connect to the server, then you will have to use the manual method described below. 5) Disable screen savers or use the "blank screen" screen saver. If this is not practical, consider raising prime95's priority to 4 or 5. The "Start at Bootup" menu choice (on by default) will run prime95 every time you boot your computer. The "Start at Bootup" choice became "Start at Logon" starting with Windows Vista. MANUAL METHOD INSTRUCTIONS -------------------------- 1) Visit http://mersenne.org/update/ to create a userid for yourself and http://mersenne.org/manual_assignment/ to get an exponent or two to work on. Copy these exponents to a file called worktodo.txt. 2) Run prime95.exe. You will see 3 dialog boxes: 2a) In the welcome dialog box, choose "Join GIMPS!". 2b) In the second dialog box, fill in roughly how many hours a day you leave your computer running. Click OK. 2c) In the third dialog box, uncheck "Use PrimeNet to get work and report results", click OK. 3) Disable screen savers or use the "blank screen" screen saver. If this is not practical, consider raising prime95's priority to 4 or 5. 4) When done with your exponents, use the web pages again to send the file "results.txt" to the PrimeNet server and get more work. The "Start at Bootup" menu choice (on by default) will run prime95 every time you boot your computer. The "Start at Bootup" choice became "Start at Logon" starting with Windows Vista. NOTES ----- Running prime95 may SIGNIFICANTLY INCREASE YOUR ELECTRIC BILL. The amount depends on your computer and your local electric rates. It can take many CPU weeks to test a large Mersenne number. This program can be safely interrupted by using the ESC key to write intermediate results to disk. This program also saves intermediate results to disk every 30 minutes in case there is a power failure. You can compare your computer's speed with other users by checking the web page http://mersenne.org/report_benchmarks/. If you are much slower than comparable machines, there are several utilities available (such as TaskInfo2002, http://www.iarsn.com/) that can find programs that are stealing prime95's CPU cycles. You can get several reports of your PrimeNet activity at any time by logging in at http://mersenne.org/. If you have overclocked your machine, I recommend running the torture test for a couple of days. The longer you run the torture test the greater the chance that you will uncover an error caused by overheating or overstressed memory. Depending on the exponent being tested, the program may decide that it would be wise to invest some time checking for small factors before running a Lucas-Lehmer test. SETTING UP A PROXY SERVER ------------------------- Choose the "Connection..." button in the Test/Primenet dialog box. Fill in the proxy information. SETTING P-1/ECM STAGE 2 MEMORY ------------------------------ Stage 2 of P-1 factoring step prior to running a Lucas-Lehmer test is slightly more effective if it is given more memory to work with. However, if you let the program use too much memory then the performance of ALL programs will suffer. The good news is that 98% of the time the program uses a minimal amount of memory. In fact, the program will work just fine if you never let it use more than the minimum. So how do you intelligently choose the memory settings? Below are some steps you might take to figure this out: 1) Be conservative. It is better to set the memory too low than too high. Setting the value too high can cause thrashing which slows down all programs. Remember, the program will only use the extra memory in stage 2 of P-1 factoring (about 12 hours a month). 2) Start with how much memory is installed in your machine. Allow a reasonable amount of memory for the OS and whatever background tasks you run (say 100 or 200MB). This represents the maximum value you should use. The program won't let you enter more than 90% of installed memory. 3) Assuming you run your machine 24 hours a day, what hours of the day do you not use your computer? Make these your nighttime hours and let the program use a lot of memory during these hours. But reduce this value if you also run batch jobs at night. 4) Factor in the information below about minimum, reasonable, and desirable memory amounts for some sample exponents. If you choose a value below the minimum, that is OK. The program will simply skip stage 2 of P-1 factoring. Exponent Minimum Reasonable Desirable -------- ------- ---------- --------- 20000000 40MB 80MB 120MB 33000000 65MB 125MB 185MB 50000000 85MB 170MB 250MB For example, my machine is a dual-processor with 512MB of memory. I guess Windows XP can survive on 100MB of memory. Thus, I set memory to (512 - 100) or ~400MB. This is my nighttime setting. During the day, I set memory to 80MB. I can always stop prime95 if it is doing P-1 factoring and I detect memory thrashing. More casual users will probably want to set the daytime memory to 8MB so they don't have to worry about prime95 impacting system performance. If at all in doubt, leave the settings at 8MB. The worst that will happen is you end up running a Lucas-Lehmer primality test when stage 2 of P-1 factoring would have found a factor. PROGRAM OUTPUT -------------- On screen you will see: Factoring M400037 to 2^54 is 3.02% complete. Time: 0.121 sec. This means prime95 is t...
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