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search for small factors on a set of Mersenne numbers and compare the results.

Round off checking. This option will slow the program down by about 15%.

This option displays the smallest and largest "convolution error". The

convolution error must be less than 0.49 or the results will be incorrect.

There really is no good reason to turn this option on.

The Priority menu is used to adjust the priority prime95 runs at.

You should not need to change this. You might raise the priority

if you (or your coworker) just cannot live without your screen

saver (bad idea), or if you are running some ill-behaved program

that is using CPU cycles for no good reason.

The Manual Communication menu choice should only be used if the

automatic detection of an Internet connection is not working for you.

Using this option means you have to remember to communicate with the

server every week or two (by using this same menu choice).

The Quit GIMPS menu choice is used when you no longer want this computer

to work on the GIMPS project. You may rejoin at a later date.

If you are a PrimeNet user your unfinshed work will be returned to the

server. If you are a manual user, you need to send me email containing

your results.txt file and a note saying you are quitting.

OPTIONS MENU

------------

The CPU menu choice lets you tell the program what kind of CPU you

have. The program will normally figure this information out for you.

This information is used to give accurate time estimates in the

Test/Status menu choice. It is also used, to choose between integer

based factoring (Cyrix and 486) and floating point based factoring

(Pentium and Pentium Pro). No matter what you choose, the program

uses the same code to run the Lucas-Lehmer primality test. If you have

an AMD K5 or Cyrix M2 chip, choose Cyrix 6x86.

The Preferences menu choice lets you control how often a line is

written to the main window. Also how often a line is written to

the results file. It also lets you change how often

intermediate files (to guard against power failure an crashes)

are created. You can control how often the program checks to

see if you are connected to the Internet. The program polls

whenever it has new data to send to or work to get from the PrimeNet

server. If you are low on disk space, you can select one intermediate

file instead of two. However, if you crash in the middle of writing

the one intermediate file, you may have to restart an exponent from

scratch. You can also tell the program to be quiet, rather than

beeping like crazy, if a new Mersenne prime is found.

The Self Test choice lets you run a sixteen-hour self test. Passing the

self-test does not guarantee that you will not run into any hardware

problems later on, but it does give you some confidence that the program

is working properly.

The Torture Test choice will run a continuous self test. This is great

for testing machines for hardware problems.

The Tray Icon choice will cause prime95 to have a small icon on the taskbar

when it is minimized. You can activate the program by double-clicking on

the small icon. If you place the cursor over the small icon, a tooltip will

display the current status.

The No Icon choice is only enabled if the Advanced Menu is activated

with the password. Using this menu choice means there will be no

prime95 icon on the taskbar once you minimize the program (making it very

hard to reactivate!) If you turn this feature on and want to turn it

back off, edit prime.ini and change the line "HideIcon=1" to "HideIcon=0",

then reboot.

Checking the Windows 95 Service menu choice will install prime95

as a service. The program will be run automatically whenever

you reboot your machine. You will not need to place a shortcut to

prime95 in the startup menu.

COMMAND LINE ARGUMENTS

----------------------

These command line arguments can be used to schedule prime95.exe to

run only at certain times of the day or at a different priority. Note

that raising the program's priority will not make it run any faster

on an idle machine.

-Tdd:hh:mm This tells the program to terminate itself after

the specified number of days, hours, and minutes.

The days and hours are optional. For example,

use Windows 95 Plus Pack's scheduler to run the

program on your co-worker's machine for 12 hours

every evening with the -T12:00 argument.

-An This is used to run two or more copies of prime95

from the same directory. Using this switch causes prime95

to use a different set of filenames for the INI files,

the results file, the log file, and the spool file.

Just use a different value of n for each copy of

prime95.exe you start.

-Wdirectory This tells prime95 to find all its files in a different

directory than the executable.

POSSIBLE HARDWARE FAILURE

-------------------------

If the message, "Possible hardware failure, consult the readme file.",

appears in the results file, then prime95's error-checking has

detected a problem. Prime95 will continue from the last save file.

If you do not get the message, "Disregard last error...", then the

problem is not reproducible - a definite sign of hardware problems.

How can this be when none of your other programs have problems? The answer

is that prime95 stresses your machine more than any other program you

run. The operating system usually shuts down the floating-point unit

when no programs are using it. Prime95 continuously uses the FPU, consuming

more electricity and generating more heat. If the CPU is not properly cooled,

errors can occur. Prime95 also constantly accesses main memory - up to

60MB per second. This constant activity will detect memory problems that

other programs do not. This is why Cray Research has used a program similar

to this one as part of its supercomputer diagnostics package for over a decade.

Could it be a software problem? If the error is ILLEGAL SUMOUT, then

there is a good chance that this is a software problem. A device driver

or VxD may not be saving and restoring CPU state correctly. The good news

is that prime95 recovers very well from ILLEGAL SUMOUT errors.

Try seeing if the problem occurs only when a specific device is active

or a specific program is running.

How can you track down the hardware problem? Unfortunately, this is not

easy. To see if your CPU is overheating, run prime95 for several hours.

Open the box. Is the CPU too hot to touch? If so, a heat sink or

CPU fan should solve the problem. Memory problems are not as easy to

diagnose. My only advice is to try swapping memory SIMMs with a coworker's

or friend's machine. If the errors go away, then you can be confidant

that the original problems were memory related.

What can you do if you are unwilling or unable to find the hardware problem?

If you are only getting an error once in a while, then your results are

probably OK. The error-checking code is not infallible, so your results

will need to be double-checked. If you are getting several errors during

each primality test, then I would recommend using your machine to factor

Mersenne numbers.

LUCAS-LEHMER DETAILS

--------------------

This program uses the Lucas-Lehmer primality test to see if 2**p-1 is prime.

The Lucas sequence is defined as:

L[1] = 4

L[n+1] = (L[n]**2 - 2) mod (2**p - 1)

2**p-1 is prime if and only if L[p-1] = 0.

This program uses a discrete weighted transform (see Mathematics of

Computation, January 1994) to square numbers in the Lucas-Lehmer sequence.

DISCLAIMER

----------

THIS PROGRAM AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF

ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO

THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A

PARTICULAR PURPOSE.

THANKS

------

Happy hunting and thanks for joining the search,

George Woltman

woltman@magicnet.net

Welcome to the Great Internet Mersenne Prime Search!

In case you ever forget, the URL is http://www.mersenne.org/prime.htm.

My email address is woltman@magicnet.net.

For networking questions, contact Scott Kurowski at primenet@entropia.com.

FILE LIST

---------

readme.txt This file.

prime95.exe The program to factor and run Lucas-Lehmer tests on

Mersenne numbers.

rpcnet.dll Communicates with the Internet PrimeNet server using RPCs.

httpnet.dll Communicates with the Internet PrimeNet server using HTTP.

whatsnew.txt A list of new features in prime95.exe.

prime.ini A file containing your preferences. The menu choices

and dialog boxes are used to change your preferences.

local.ini Like prime.ini, this file contains more preferences.

The reason there are two files is discussed later.

worktodo.ini 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

qnnnnnnn computation where it left off.

database This optional binary file is downloaded separately. You only

need this file if you are not using the PrimeNet server.

It contains all the Mersenne exponents that still need testing.

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. Anyone with Internet access, including AOL,

CompuServe, and dial-up ISP users should use this method. 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 should

first GET PERMISSION from your network administrator or boss. This is

especially true if you are installing the software on several machines.

Some companies are reluctant to run any software they are not familiar with.

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.

3) Run prime95.exe. You will see 3 dialog boxes:

3a) In the first dialog box, enter your name and email address.

Optionally enter a user ID and password. 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. If you do not enter a user ID or if

you pick a user ID that is already in use, then the server will assign

a user ID.

3b) In the second dialog box, change the CPU type and speed if necessary.

Fill in roughly how many hours a day you leave your computer running.

Click OK.

3c) In the third 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.

4) If you cannot contact the PrimeNet server, then a firewall may be

preventing the RPCs from getting to the server. In this case, you

may want to try the HTTP-based DLL. Choose "Use HTTP-based DLL"

from the Test/Primenet dialog.

4a) If you now get the error message "Unable to load HTTPNET.DLL", then

you are probably missing WININET.DLL. This DLL is shipped with

Microsoft's Internet Explorer. It is also installed by default in

later versions of Windows 95 and Windows NT. You can download and

install WININET.DLL from Scott Kurowski's web site. See

http://entropia.com/ips/faq.html#wininet for details.

4b) If the http-based DLL will not connect to the server, then

you will have to use the manual method described below. There have

been reports that the http-based DLL does not work in all

MS IE 3.0 environments - we are working on making this DLL work in

as many different environments as possible.

4c) If a proxy server is the cause of your connection troubles, see the

later section on "SETTING UP A PROXY SERVER".

5) Create a shortcut to prime95.exe and place it in the startup folder.

Alternatively, you can install prime95.exe as a Windows 95 service

using the Options menu. Prime95 will now run every time you boot

your computer.

MANUAL METHOD INSTRUCTIONS #1

-----------------------------

1) Use the Web (http://entropia.com/ips/manualtests.html) to create

a userid for yourself and to get a set of exponents to work on.

Copy these exponents to a file called worktodo.ini

2) Run prime95.exe. You will see 3 dialog boxes:

2a) In the first dialog box, enter your name and email address. Click OK.

2b) In the second dialog box, change the CPU type and speed if necessary.

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) Create a shortcut to prime95.exe and place it in the startup folder.

Prime95 will now run every time you boot your computer.

4) Once a month or when done with your exponents, use the web pages

again to send the file "results.txt" to the PrimeNet server.

It is important to do this so the exponents you are testing are

not reassigned to someone else.

MANUAL METHOD INSTRUCTIONS #2

-----------------------------

1) Download and unzip database.zip (http://www.mersenne.org/range2.htm).

2) Use the Web (http://www.mersenne.org/range2.htm) to select a range of

exponents to test. Send me e-mail on the range you've chosen.

This prevents others from testing the same range.

3) Run prime95.exe. You will see 3 dialog boxes:

3a) In the first dialog box, enter your name and email address. Click OK.

3b) In the second dialog box, change the CPU type and speed if necessary.

Fill in roughly how many hours a day you leave your computer running.

Click OK.

3c) In the third dialog box, uncheck "Use PrimeNet to get work and report

results", click OK.

4) Choose Test/Manual Operation from the menus. Enter the type of work

and range of exponents you selected in step 2.

5) Create a shortcut to prime95.exe and place it in the startup folder.

Prime95 will now run every time you boot your computer.

6) Once a month or when done with your range, send the file "results.txt" to

woltman@magicnet.net. It is important to do this so the exponents

you've tested can be removed from the master list.

NOTES

-----

Let prime95.exe run at all times. It runs at the lowest possible priority,

making use of all your idle CPU cycles. It should not interfere with your

normal work. Let the program run overnight and on weekends. Never turn

your computer off. Turn off your monitor to conserve energy. NOTE:

Running your computer non-stop could increase your electric bill by $30

per year or more.

It can take many CPU days 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.

To fully utilize a dual Pentium machine, you must run two copies of

prime95.exe. Run one copy of prime95 as described above. Run the second

copy of prime95.exe with the -A1 switch. Place two shortcuts in the