are running a slow computer and don't mind waiting several months for
a single Lucas-Lehmer test to complete OR you are running a faster
computer and would rather do factoring, then uncheck this box and
choose a different type of work to do. The "Days of work to get" should
be changed based on how often you connect to the Internet. As long as
you connect at least once in the given time period, prime95 will have
an uninterrupted stream of work. However, the program will not checkout
more than 20 exponents no matter what "Days of work to get" is set at.
The Manual Operation menu choice allows you to select a range of
exponents to work on. You may also use this menu choice to add
to your existing work (e.g. when you are running low on exponents
to test).
The User Information menu choice lets you change your name and email
address. Your name will be used in credits and "top producers"
web pages. Your email address will be used to send you warnings if
an exponent you have reserved is about to expire and to send you a
newsletter once every few months. Select the no email checkbox to
stop the server from sending expiration warnings. The userid you
use will appear in the status pages on the PrimeNet server. You can
also set the ComputerID field if you have several computers and want
to keep track of which computers produced which results.
The Vacation/Holiday menu choice lets prime95 update the expected completion
dates on the PrimeNet server. This will prevent one of your exponents
from being reassigned while you're gone. Also, if you are taking a
long vacation, prime95 will get extra exponents to test. For example,
if you are leaving immediately for a 6 week vacation, connect to the
Internet and choose 42 days. If you are leaving in two days for a 6
week vacation, then set choose 44 days. Primenet will send the new
completion dates whenever you connect to the Internet over the next 2 days.
The Status menu choice will tell you what exponents you are working on.
It will also estimate how long that will take and
your chances of finding a new Mersenne prime.
The Continue menu choice lets you resume prime95 after you have stopped it.
The Stop menu choice lets you stop the program. When you continue,
you will pick up right where you left off. This is the same as hitting
the ESC key.
ADVANCED MENU
-------------
You should not need to use the Advanced menu. This menu choice is
provided only for those who are curious to play with. To avoid confusion
for novice users, all the choices in the Advanced menu have been grayed.
Please read this section if you want to know what the Advanced menu choices
do. To turn on the Advanced menu, use the Advanced Password dialog box
and enter a value of 9876. Also note that many of the menu choices are
grayed while testing is in progress. Choose Test/Stop to activate
these menu choices.
The Test choice can be used to run a Lucas-Lehmer test on one Mersenne
number. Enter the Mersenne number's exponent - this must be a prime
number between 7 and 5259999.
The Time choice can be used to see how long each iteration of a Lucas-Lehmer
test will take on your computer and how long it will take to test a
given exponent. For example, if you want to know how long a Lucas-Lehmer
test will take to test the exponent 876543, choose Advanced/Time and
enter 876543 for 100 iterations. A Pentium will automatically time
and compute the results. 486 owners will need to time how long the operation
takes by hand, divide that time by 100 and multiply by 876543 to compute how
long a full Lucas-Lehmer test will take.
The ECM choice lets you factor small Mersenne exponents using the
Elliptic Curve Method of factoring. Select a few exponents and bounds
to factor from the http://www.mersenne.org/ecm.htm web page.
Note: You do not reserve exponents to work on, several people can
do ECM factoring on the same exponent. The program uses a random
number generator to select elliptic curves to test. You must email
results to me at woltman@magicnet.net - primenet does not support ECM
factoring. You can also edit the worktodo.ini file directly. For example:
ECM=751,3000000,0,100,0,0,0
The first value is the exponent. The second value is bound #1. The
third value is bound #2 - leave it as zero. The fourth value is the
number of curves to test. The fifth value is the number of curves completed.
The sixth value is the specific curve to test - it is only used in
debugging. The seventh value is 0 for 2^N-1 factoring, 1 for 2^N+1
factoring.
The Clear Primes choice can be used to remove one or more exponents from the
database. You might do this for two reasons:
1) Let's say you're testing range 1234000 to 1234999. If I send you some
mail saying that a factor has been found for M1234567, then you use
Clear Primes to remove 1234567 from your database so that you
won't have to run a Lucas-Lehmer test on it.
2) You downloaded a new database after checking all the exponents
between 1234000 and 1234300. You can use Clear Primes
to remove the exponents between 1234000 and 1234300.
Do not use the Factor menu choice. If you're running Lucas-Lehmer tests
on a range or just factoring a range - use Test/Manual Operation.
The program will know the optimal amount of factoring to perform. Having
said that, if you insist on using this menu choice, you can look for factors
less than 2^62 of any Mersenne numbers with an exponent less than 10,000,000.
Let's say you're writing a factoring program for a UNIX machine and want to
check its results. Use both this menu choice and your UNIX program to
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.