whatsnew.txt

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    error recovery of the new P4 FFT introduced in the beta version 21.2.

New features in Version 21.2 of prime95.exe
-------------------------------------------

1)  The program now uses the SSE2 instructions introduced on the Pentium 4 CPU.
    This version is about 3 times faster than the previous version on a P4.
2)  The program now uses the prefetch instructions on the Celeron 2, Pentium 3,
    and all Athlon CPUs.  This results in about a 20% performance boost on
    these machines.
3)  Process priority is now set to idle.  Microsoft documentation says that
    an idle thread priority overrides process priority.  The program's
    priority scheme has always worked well.  However, several Win2K users
    have reported that the program works better if the process priority is
    also set to idle.
4)  The program now delays calculations until 90 seconds after bootup.  This
    lets your machine boot up as fast as possible.  This can be changed, see
    undoc.txt.
5)  The default crossover between double-check assignments and first-time
    tests has been increased to a 400 MHz PII.
6)  After 5 1/2 years, a help file now exists!  It is HTML Help which may
    have problems on older Windows machines.  If so, try downloading
    hhupd.exe from Microsoft's web site.
7)  The program used to do factoring and P-1 testing on new exponents before
    completing LL tests on older exponents.  This was confusing to many.
    The program now processes the worktodo.ini file in sequential order.
    See undoc.txt on how to restore the old behavior.
8)  Error messages such as ILLEGAL SUMOUT, SUMINP != SUMOUT, etc. are no
    longer sent to the server since the final result contains a count of how
    many errors occured during the LL test.
9)  Some of the FFT crossover points have changed slightly.
10) Test/Status now outputs the day of the week each work item will complete.
11) Interim output lines have changed - hopefully, so they are more useful
    especially to newbies.  By default, output lines no longer contain the
    clocks count.  Lines now contain a timestamp.  Benchmark timings are now
    output in milliseconds.  These defaults can be changed using options
    in undoc.txt.
12) A new welcome screen for new users will encourage stress testers
    to use the program without reserving exponents.
13) There is now a menu choice that lets you unreserve a specific exponent.
    This is for knowledgable users only.  You might do this if the server
    assigned a small exponent and you'd rather be testing larger ones.  Or
    the prime95 you set up on another machine had a hard drive failure.
14) The Windows 9x Service menu choice has been replaced by the more general
    Start at Bootup menu choice.  This choice now sets registry entries to
    autostart prime95 on any Windows machine.  WARNING:  Using this option
    will delete any StartUp menu shortcuts so the registry entry and startup
    menu do not both try to start prime95.
15) Prime95 will now ask for confirmation if you enter a CPU speed that
    differs from the computed CPU speed by more than 4%.
16) The self-test menu choice was deleted - use the torture test instead.
17) A benchmark menu choice has been added.
18) The torture test code now includes more FFT lengths including smaller
    ones that run completely in the L2 cache which may increase CPU
    temperatures.  Each FFT size is tested for 15 minutes by default.
    There are now several options in the undoc.txt for fine tuning the
    torture test's behavior.

New features in Version 20.6 of prime95.exe
-------------------------------------------

1)  A crash bug was fixed.  If you did P-1 factoring followed by trial
    factoring, then if you found a factor unallocated memory was accessed
    usually resulting in a crash.

New features in Version 20.5 of prime95.exe
-------------------------------------------

1)  A rare error was fixed.  When the memory settings changed during the
    GCD step in P-1 or ECM factoring, then a spurious "ERROR: Factor
    does not divide N!" error was raised.

New features in Version 20.4 of prime95.exe
-------------------------------------------

1)  If stage 2 of P-1 was postponed because of insufficient memory, the
    program did not restart stage 2 when nighttime started.  This bug was
    fixed.
2)  By default, PII-300's and faster get first-time LL tests, P-90 and faster
    get double-checking work, and all slower machines get factoring work.
3)  An ECM bug during stage 2 init on huge exponents caused false ILLEGAL
    SUMOUT errors.  This bug was fixed.

New features in Version 20.3 of prime95.exe
-------------------------------------------

1)  Another fairly uncommon ECM bug was fixed.  The bug caused "Factor does
    not divide N!" errors.
2)  A couple of minor bugs in computing the optimal P-1 bounds to use prior
    to a Lucas-Lehmer test were fixed.  The program now does a better job at
    estimating the memory required in P-1 stage 2.  Finally, although P-1
    stage 2 working set size is unchanged, the program allocates less memory
    in stage 2.
3)  Prime95 no longer searches for a smaller factor when trial factoring
    discovers a factor.  The reasons are two-fold.  1)  Version 19 had a
    bug where stopping and restarting the program bypassed the search for
    smaller factors.  Thus, my database may already be missing smaller
    factors.  2) As we factor larger exponents to a deeper depth it may
    no longer be a quick job to determine if there are smaller factors.
    Note, that version 20 will still look for smaller factors if you are
    looking for factors below 2^60 with the FactorOverride option in undoc.txt.
4)  The undocumented AMPM feature controls how times are formatted in the
    Options/CPU dialog box.

New features in Version 20.2 of prime95.exe
-------------------------------------------

1)  If P-1 stage 1 completed and there was not enough memory to start
    stage 2 immediately, then an incorrect save file was generated.  This
    bug was introduced in version 20.1.  Upon restart of the P-1 factoring
    job a crash or other unpredictable behavior was possible.  This bug was
    fixed and this version has special code to properly read these
    incorrect save files.
2)  P-1 will restart any time the memory settings change.  This is done
    so that the optimal P-1 bounds can be computed with the new memory
    settings.
3)  A bug in ECM testing was fixed.

New features in Version 20.1 of prime95.exe
-------------------------------------------

1)  A bug in the new GCD code was fixed.
2)  Timings in the P-1 stage are no longer cumulative.  There is a new
    feature in undoc.txt for those that prefer cumulative timings.
3)  Messages are now output prior to beginning the lengthy GCD.
4)  The FactorOverride undocumented feature (not for use with PrimeNet) now
    supports factoring to a deeper level than prime95 would ordinarily factor.
5)  A bug where the worktodo.ini entry was not removed if P-1 found a factor
    was fixed.
6)  If P-1 finds a factor it now deletes any Lucas-Lehmer intermediate files.
7)  A crash bug when continuing from a P-1 stage 2 save files with
    different available memory parameters was fixed.
8)  Resuming an LL test now outputs a line to the screen,
9)  The Test/Status display now correctly calculates the estimated completion
    time for an LL test when P-1 factoring is in progress.
10) Advanced/Factor menu choice was deleted.
11) A bug in computing P-1 stage 2 percentage complete was fixed.

New features in Version 20.0 of prime95.exe
-------------------------------------------

1)  The program now does some P-1 factoring prior to running first time
    and double-checking Lucas-Lehmer tests.  This will increase overall
    GIMPS throughput.  If you install version 20 in the middle of an LL test
    the program will run the P-1 step if the LL test is less than 50%
    complete.
2)  The Options/CPU dialog box now asks how much memory the program can
    use during the P-1 factoring.  See the "Setting Available Memory"
    section in the readme.txt file.
3)  Stage 1 of P-1 factoring is now faster.
4)  The GCD used in P-1 and ECM factoring is now faster.
5)  The Test/Manual Operation menu choice has been deleted.
6)  The memory options in P-1 and ECM dialog boxes have been deleted.
7)  The "send new completion dates" checkbox was moved from the Test/Primenet
    dialog box to the Advanced/Manual Communication dialog box.
8)  A bug in estimating time remaining for a factoring job was fixed.
9)  AdvancedFactor now writes a line to the worktodo.ini - just like all
    the other work types.
10) ECM and P-1 are now consistent with Lucas-Lehmer testing in the use
    of the "Iterations between screen outputs" setting.  An iteration is
    defined as the time it takes to do a squaring.  If you are doing ECM
    on small exponents you will probably want to increase this setting.

New features in Version 19.2 of prime95.exe
-------------------------------------------

1)  A bug in factoring exponents above 35.79 million was fixed.

New features in Version 19.1 of prime95.exe
-------------------------------------------

1)  A new undocumented feature, Stage1GCD, lets you speed up P-1 tests
    on large exponents - see undoc.txt for details.
2)  K6 CPUs now default to the Pentium code path instead of the Pentium
    Pro code path.  This is faster on the K6.
3)  The rolling average formula was adjusted to work better on machines
    that are not on 24 hours a day.

New features in Version 19.0 of prime95.exe
-------------------------------------------

1)  Faster - in some cases as much as 10% faster!.  The FFTs were recoded
    for improved memory and TLB efficiency.  Furthermore, optimizations
    specific to the Pentium Pro and later processors were added.
2)  New FFT lengths.  The program can now test exponents as large as
    79.3 million.  Also, smaller FFT lengths are supported for use in
    ECM and P-1 factoring.
3)  More conservative FFT breakpoints.  This could actually result in
    some exponents being slower to test in this version.  However, the
    chance of a fatal rounding error has been reduced.
4)  P-1 factoring has been added.  Although it is not very practical for
    large exponents because of a slow GCD routine, it can be used to
    find new factors of exponents below a few million or so.
5)  ECM can now run on large exponents.  Once again, the slow GCD routine
    and high memory requirements might make this impractical for large
    exponents.
6)  ECM and P-1 factoring now support save files.  Very handy on lengthy runs.
    The count of completed ECM curves is maintained in the save file instead
    of the worktodo.ini file.
7)  ECM and P-1 factoring lets you specify the amount of memory to use.
    In some cases, more memory can improve execution speed slightly.
8)  A bug in guessing the CPU speed on initial install has been fixed.
9)  The preferences dialog now has an option to pause prime95 when a laptop
    is running on its battery.
10) Error checking has been improved slightly.
11) Factoring is now "layered".  That is, prime95 now factors to 2^50, then
    2^51, 2^52, and so forth up to the appropriate limit.  The factoring
    output lines have been changed to show percent complete in the current
    "layer".
12) A bug in running two or more self or torture tests in the same directory
    has been fixed.
13) Trial factoring above 2^64 is now supported.
14) More trial factoring is now done to take into account the cost of
    double-checking.
15) Title now contains percent complete when LL testing.  By default, the
    percent complete value is now displayed to 2 decimal places.  You can
    change this by setting PercentPrecision in prime.ini to a value
    between 0 and 6.
16) Affinity and service name settings moved from prime.ini to local.ini file.
    Prime95 will automatically move these settings for you.
17) An option to get only 10,000,000 digit numbers to run primality tests
    on has been added to the Test/Primenet dialog box.  See
    http://www.mersenne.org/prize.htm for rules on claiming the EFF award
    for finding a 10,000,000 digit prime.
18) The Advanced/Clear primes menu choice has been deleted.
19) The prime95 icon turns yellow when the program is idle.  After an
    error such as ILLEGAL SUMOUT, the icon will blink for 10 seconds.
20) The User Information dialog box allows you to request newsletters and
    form a team user ID where the team members cannot alter the team name.
21) A bug in the reporting of error counts in the results.txt file has
    been fixed.
22) The server can now broadcast important messages to the prime95 client.
    Prime95 will blink the icon until prime95 is activated and then it will
    display the message.
23) A computer ID will be generated for computers that do not have one.  If
    you want to assign your own computer ID, please try to make each
    computer ID using the same user ID unique.

New features in Version 18.1 of prime95.exe
-------------------------------------------

1)  Added code so that server can distinguish between a v17 and v18 client.
2)  Only v17 save files above 4194304 are deleted.

New features in Version 18.0 of prime95.exe
-------------------------------------------

1)  Bug fixed in Lucas-Lehmer testing of exponents above 4194304.

New features in Version 17.2 of prime95.exe
-------------------------------------------

1)  Faster 2^N+1 ECM factoring.

New features in Version 17.1 of prime95.exe
-------------------------------------------

1)  The -T command line switch has been deleted.
2)  You can now fine tune your control of the program by adding Time=
    lines to your prime.ini file - see the readme.txt file.
3)  ECM factoring for 2^N+1 is now available.
4)  By default, ECM factoring stops if a factor is found for exponents
    above 5825 and continues (if the cofactor is composite) for exponents
    below 5825.  You can override this behavior by setting ContinueECM=0
    or 1 in prime.ini.

New features in Version 17.0 of prime95.exe
-------------------------------------------

1)  Prime95 can now be used to double-check its own results.
2)  Machines less powerful than a P133 will default to double-checking
    assignments.
3)  The total number of errors that occur during the Lucas-Lehmer test
    are now output in results.txt.

New features in Version 16.5 of prime95.exe
-------------------------------------------

1)  A new httpnet.dll can provide Scott Kurowski with debugging information.
    Simply create a primenet.ini file with these lines:
	[Debug]
	PacketLog=1
    Output file is pnHttp.txt.
2)  The old network retry time has been replaced by two settings.
    The modem retry time (default 2 minutes) controls how often prime95
    polls your modem to see if you are connected to the Internet.
    The network retry time (default 60 minutes) controls how long prime95
    waits after a failed attempt to contact the server.
3)  A timestamp and program version number is written to the prime.log file.