New features in Version 27.3 of prime95.exe
-------------------------------------------

1)  64-bit optimizations for AVX-capable computers.  Single core benchmarks on Intel Sandy
    Bridge computers should see a decent speed increase.  However, running on 4 cores
    runs into main memory bandwidth bottleneck.  Sandy Bridge-E CPUs with 4 memory channels
    should avoid this problem.

New features in Version 27.1 of prime95.exe
-------------------------------------------

1)  32-bit FFTs optimized for AVX-capable computers.  Intel Sandy Bridge computers should
    see a 25% speed increase.

New features in Version 26.6 of prime95.exe
-------------------------------------------

1)  For rare cases where the program cannot figure out the number of cores and hyperthreading,
    the NumPhysicalCores option may help.  See undoc.txt.
2)  Faster FFT implementations are now selected for Core 2 CPUs with 1MB L2 cache or less
    (marketed under the Celeron and Pentium label).
3)  New, slightly higher, trial factoring breakeven points.

New features in Version 26.5 of prime95.exe
-------------------------------------------

1)  Minor bug fixes.
2)  Starting in build 2, P-1 work will display the chance of finding a factor.
    The worktodo.txt line must include how_far_factored using the new syntax:
	Pminus1=k,b,n,c,B1,B2[,how_far_factored][,B2_start][,"factors"]
3)  Starting with build 3, at startup the program tries to determine which
    hyperthreaded logical CPUs comprise one physical CPU.  If this isn't working
    properly, see the AffinityScramble2 setting in undoc.txt.  The previous
    version's AffinityScramble setting is no longer supported!

New features in Version 26.4 of prime95.exe
-------------------------------------------

1)  The 64-bit version supports 64 threads (up from 32).
2)  Each on-screen window can now scroll back 1000 lines of output.
3)  ECM time estimates improved.  ECM may be a smidge faster.

New features in Version 26.3 of prime95.exe
-------------------------------------------

1)  A few crash bugs were fixed that affected only some CPU architectures and some
    FFT lengths.  Other minor bugs were fixed.

New features in Version 26.2 of prime95.exe
-------------------------------------------

1)  Faster FFTs for most SSE2-capable CPU architectures.
2)  More FFT lengths supported.
3)  Some of the new, faster FFTs don't let us do as much error checking on each iteration.
    If you don't want to lose this error checking, choose "SUM(INPUTS) error checking" from
    the Options menu.  This will slow down your tests by about 2-5%.
4)  When a possible hardware error occurs during a test, the error message would
    likely scroll off the screen unnoticed.  Now, all future progress updates to
    the screen will be followed by a message containing a count of the errors that
    have occurred during the test.
5)  Worker Windows now stagger their starts.  This improves timings for some
    CPUs and operating systems.  See undoc.txt to control this feature.

New features in Version 25.11 of prime95.exe
--------------------------------------------

1)  PRP of k*b^n+c where b > 2 will be faster in many cases.
2)  Zero-padded FFTs are about 3-4% faster.  These FFTs are used in projects
    like SeventeenOrBust.

New features in Version 25.10 of prime95.exe
--------------------------------------------

1)  A bug that caused pfactor save file names to begin with the letter p
    was fixed.  It now uses m like all other P-1 efforts.  Old save file
    names are automatically upgraded.
2)  Prime95 now recovers gracefully from more out-of-memory conditions
    when doing ECM or P-1.
3)  We now do P-1 factoring one bit level before the trial factoring limit.
    The previous version started P-1 two bit levels before the trial
    factoring limit.

New features in Version 25.9 of prime95.exe
-------------------------------------------

1)  Performance increases for the 64-bit version by taking advantage of the
    eight extra SSE2 registers.  The 32-bit version may also be a bit faster
    by taking advantage of the Core 2 architecture.  The FFT code was 
    originally optimized for the Pentium 4 where instructions like
    "movapd reg,reg" take 6 clocks and should be avoided, whereas on Core 2
    the same instruction uses just 1 clock cycle and improves scheduling.
    The 32-bit version may be slightly faster or slower on the Pentium 4, but
    not enough to worry about.  Preliminary benchmarks indicate:
	32-bit Pentium 4:	between 2% slower and 1% faster
	32-bit Core 2:		between 2% and 6% faster
	64-bit Pentium 4:	between 2% and 4% faster
	64-bit Core 2:		between 10% and 13% faster
	64-bit Core i7:		between 7% and 12% faster
	64-bit Phenom:		between 10% and 13% faster
	AMD64:			between 1% slower and 1% faster
2)  Intermediate save files were overhauled.  Trial factoring, P-1, and
    ECM now support multiple save files.  The backup save file uses a .bu
    extension.  While a new save file is being written a .write extension
    is used and renamed when successfully written (thus, briefly there are
    3 save files). NOTE #1: LL save files no longer use an initial letter
    of q and r.  The program will automatically use these obsolete files if
    necessary and delete them when no longer needed.  NOTE #2: ECM and P-1
    save files on k*2^n+1 no longer use file names beginning with d and l.
    The -An command line argument no longer appends an extension to save
    file names.  NOTE #3: The client now supports keeping three save files.
3)  Miscellaneous minor bug fixes.

New features in Version 25.8 of prime95.exe
-------------------------------------------

1)  Bug fixed in smart affinity on hyperthreaded CPUs.
2)  Bug fixed in setting a thread priority other than 1.
3)  Off-by-one-bit bug fixed in the benchmarking of trial factoring.
4)  In rare case an infinite loop could occur when the computer ID
    in the spool file did not match the current computer ID.
5)  The "days between checkin" value now has a range of 1 to 7 days.
    In version 24, the range was 1 to 60 days with a default of 28 days.
6)  Fixed bug where switching users on a Windows machine caused computer
    GUIDs to be erroneously regenerated.  You may need to suffer through
    one more regenerated GUID before the fix takes effect. 
7)  A bug where some low memory situations on a multi-core machine resulted
    in one or more worker threads sat idle has been fixed.
8)  A crash bug doing 61 and 62 bit trial factoring on Pentium CPUs that
    do not support the CMOV instruction was fixed.  On these same CPUs
    a bug was fixed when factors smaller than 2^60 was found.

New features in Version 25.7 of prime95.exe
-------------------------------------------

1)  Time= in ini files no longer supported.  A during/else syntax can be
    unsed instead for some ini file options.
2)  PauseWhileRunning enhanced to pause any number of workers.
3)  LowMemWhileRunning added.
4)  Ability to stop and start individual workers added.
5)  DayMemory and NightMemory in local.txt replaced with a single Memory
    setting.
6)  Memory can be set for each worker thread.
7)  Scheme to distribute available memory among workers needing a lot of
    memory has been completely revamped.
8)  MaxHighMemWorkers replaces delayStage2Workers option.
9)  The executable now defaults to talking to the PrimeNet v5 server.  To
    use the executable with the old v4 server, add "UseV4=1" to the top
    of prime.txt.

New features in Version 25.5 of prime95.exe
-------------------------------------------

1)  Multiple LL tests can be run within a single prime95 instance.  There is
    no longer a need to run multiple instances of prime95 on multi-cpu
    machines.
2)  Uses a new version of the Primenet server.  Features include user IDs that
    are different than team IDs.  New work types.  Ability to set some client
    options using web-based forms.
3)  Communication with the server runs in a separate thread.
4)  The CURL library is used for communication with the server.  Hopefully
    this will support a wider variety of client networking configurations.
5)  Supports using multiple logical or physical CPUs on a single LL test.
    Except for some hyperthreaded CPUs and only on some FFT sizes, this is
    not recommended as you will get more throughput by giving each CPU
    its own number to test.
6)  ECM and P-1 now support B1 and B2 values above 4.29 billion.  ECM now
    pays attention to the memory settings in the Options/CPU dialog box.
7)  Several files have been renamed so that they are not changed by Windows
    save/restore.  Prime.ini is now prime.txt.  Local.ini is now local.txt.
    Worktodo.ini is now worktodo.txt.  The primenet.ini file has been
    deleted - it is now a section within the prime.txt file.
8)  It is now legal to put comment lines in the prime.txt, local.txt, and
    worktodo.txt files.
9)  In older versions, editing the worktodo.ini file while prime95 was running
    sometimes had the desired effect.  That is no longer the case.  You can
    create a worktodo.add file to add work to a running prime95.
10) WARNINGS:  Previous versions of prime95 will not be able to read save files
    generated by this version.  This version will not be able to continue from
    P-1 save files generated by the previous version in the middle of stage 2.
    This version cannot read a prime.spl file generated by a previous version.
11) Program can now do PRP tests of (k*b^n+c)/f.  Add a line worktodo.txt that
    looks like this:
	    PRP=k,b,n,c[,how_far_factored,tests_saved][,known_factors]
    The optional how_far_factored (in bits) and tests_saved values are used
    to determine if P-1 factoring prior to the PRP test would be beneficial.
    The optional known_factors list is a quoted comma separated list of
    known factors of k*b^n+c. 
12) The program no longer does a one-hour self-test before testing an exponent
    with a new FFT length.
13) You can now copy the contents of a window to the clipboard.
14) New icon colors.  Green means "go".  Red means "stopped".
15) The torture test dialog box lets you choose how many CPUs or cores you
    want to torture test.
16) The benchmark times both single-threaded and multi-threaded FFTs.
17) The Advanced menu no longer needs a password.


New features in Version 24.15 of prime95.exe
--------------------------------------------

1)  To limit prime95's impact on computer responsiveness on a hyperthreaded
    machine the program now pauses for 30 seconds if two successive iterations 
    take 40% longer than a typical iteration.  You can adjust this feature
    using the HyperthreadingBackoff setting described in undoc.txt.

New features in Version 24.14 of prime95.exe
--------------------------------------------

1)  A bug that caused the torture test to hang on 256K FFTs on SSE2 machines
    with 128K of L2 cache was fixed.

New features in Version 24.13 of prime95.exe
--------------------------------------------

1)  Celeron D (256K L2 cache) and Willamette (also 256K L2 cache) now have
    different implementations for several FFT sizes.  This results in an
    improvement of several percent for the Celeron D.
2)  A bug that caused some machines to generate "Error 2252" when communicating
    with the server was fixed.
3)  SSE2 trial factoring code had a bug when factoring very large exponents.

New features in Version 24.12 of prime95.exe
--------------------------------------------

1)  For SSE2 machines the larger FFTs have been changed to more effectively
    use a wide variety of L2 cache sizes.  The previous version was optimized
    for a 256KB L2 cache only.  Depending on your CPU and FFT size, you could
    see an improvement of several percent.
2)  As a side "benefit" even larger FFT sizes are now supported.  This allows
    testing of exponents up to 596 million.  Not recommended.
3)  The factoring breakeven points have been recalculated using my 2 GHz P4.
    This version of prime95 will do less trial factoring.
4)  Since server database crashes cause spurious error 3 messages, prime95
    will now ignore error 3 messages from the server for 72 hours.  This should
    workaround the problem whereby a result is reported but no CPU credit is
    given and the reservation is not cleared.
5)  Fixed crash bug trial factoring exponents above 286 million.

New features in Version 24.11 of prime95.exe
--------------------------------------------

1)  Faster FFTs for AMD64 using prefetchw in both 32-bit and 64-bit mode.
    You can expect about a 15% speed improvement.
2)  Prime95 now detects support for 3DNow! instructions.  See undoc.txt
    for overriding this detection with CpuSupports3DNow=n in local.ini.
3)  Factoring entries in worktodo.ini now accept exponents up to 2 billion.
4)  Improved checking for memory allocation errors during a torture test.
    Better guessing of amount of memory to use in a blend test.
5)  Added timeouts to PrimeNet communications in hopes of avoiding rare hangs
    when contacting the PrimeNet server.
6)  Fixed rare bug where P-1's GCD could miss a factor.
7)  Added trial factoring to the benchmark.
8)  Fixed bug in ECM when using zero-padded FFTs.
9)  SSE2 macros optimized for an additional 1-3% improvement on P4 and AMD64
    CPUs.

New features in Version 24.10 of prime95.exe
--------------------------------------------

1)  64-bit version of prime95 available for 64-bit Windows.

New features in Version 24.9 of prime95.exe
-------------------------------------------

1)  Fixed crash when running on machines with "no-execute" protection.
2)  Fixed mis-detection of some P3 and Celeron CPUs.

New features in Version 24.6 of prime95.exe
-------------------------------------------

1)  Athlon users should see a 20% to 30% speed increase.
2)  Pentium, Pentium II, Pentium III users should see dramatically WORSE
    performance.  Run version 23 instead.
3)  P-1 and ECM now support numbers of the form k*b^n+c.  This cannot be done
    from the menus.  Add these entries to worktodo.ini:
	Pminus1=k,b,n,c,B1,B2
	ECM2=k,b,n,c,B1,B2,curves_to_do[,specific_sigma]

New features in Version 23.9 of prime95.exe
-------------------------------------------

1)  The blend torture test now uses less memory by default to prevent
    thrashing.  The in-place torture test is now the default more cases
    to reduce complaints dealing with memory allocation issues (no pagefile,
    thrashing, etc.)
2)  A bug in continuing after finding a factor when using AdvancedFactor was
    fixed.

New features in Version 23.8 of prime95.exe
-------------------------------------------

1)  A communication bug, Primenet Error 1, was fixed in the case where
    proxy software inserted the text "NetAnts: MaxConnection=1" in the HTML
    response from the Primenet server.
2)  Fixed memory allocation bug in torture test when using 926MB of memory
    on the 20K FFT size.
3)  The program will now try both full and a relative URL in trying to
    contact the PrimeNet server.  Some rare setups only work with full URLs
    and some only work with relative URLs.  The small downside is there might
    be an increase in network traffic when the server is down.  If this is
    a concern you can use the UseFullURL option described in undoc.txt.    

New features in Version 23.7 of prime95.exe
-------------------------------------------

1)  A bug was fixed where the torture test used more virtual memory than
    necessary, sometimes resulting in an "Out of memory" error.

New features in Version 23.6 of prime95.exe
-------------------------------------------

1)  Several changes have been made to the torture test.
    a) Machines faster than 1 GHz will use new test data that runs a lot more
       iterations.  This will reduce time spent in initialization code,
       hopefully increasing stress on the CPU.
    b) The torture test stops after 100 ILLEGAL SUMOUT errors.
    c) There are now 3 flavors of torture testing.  One that operates on small
       FFTs only, theoretically maximizing FPU stress.  One that operates 
       in place on large FFTs only, maximizing heat and power drain.  One that
       runs a blend of tests using lots of memory, possibly catching errors
       that might only occur at a specific memory address.

New features in Version 23.5 of prime95.exe
-------------------------------------------

1)  Four changes have been made after GIMPS' first false positive report
    in 7 1/2 years of operation.
    a) The program now returns the number of errors that occurred when the
       result is prime.  A non-zero value will make us more suspect of the
       reported prime.
    b) The save files will not be deleted.  The user can then email these to
       me and we can rerun the last 30 minutes of the LL test.  It is hard
       to imagine a second false positive report in this mini LL run.
    c) The shift counter is now checked every iteration.  If this variable
       AND the FFT data was corrupted, then and endless loop of LL iterations
       generating zero is possible - resulting in a false prime report.
    d) Every iteration the FFT data is checked to see if the data has been
       zeroed.
    e) The is-this-a-prime check now makes sure the FFT data is not NaN.
       NaN stands for not a number and means the data is corrupt.  The
       previous version checked for zero and my C compiler returns TRUE for
       the test NaN == 0.0!
2)  I restored the old behavior sending relative URLs.  Some users had trouble
    with this feature introduced in 23.4.  So, UseFullURL=0 is now the default.
3)  Some prefetching improvements were made for the Athlon, Pentium 3, and 
    Celeron 2 processors.  You can expect speed improvements between 3%
    and 10% for most FFT sizes.  Warning: the new code is slower for Durons
    and Celeron's with small L2 caches for FFT sizes 1024K and above.

New features in Version 23.4 of prime95.exe
-------------------------------------------

1)  Further performance improvements in the SSE2 FFT code.  I've tried to
    do more work while data is in the L1 data cache.
2)  The program should now work with a "redirected proxy server".  This was
    done by sending full URLs in Primenet requests.  While I don't anticipate
    any problems, the old relative URL functionality can be had by setting
    UseFullURL=0 in primenet.ini.
3)  A bug in the assembly language add and subtract routines was fixed.  The
    bug could affect ECM on exponents just below
    MAXIMUM_EXPONENT_FOR_FFTLEN - FFTLEN/2.

New features in Version 23.3 of prime95.exe
-------------------------------------------

1)  Further performance improvements in the SSE2 code for FFTs larger than
    640K.  You should see about a 4% improvement in LL tests on a P4.  However,
    FFTs between 40K and 512K might be a tiny bit slower.
2)  Stage 2 of P-1 factoring has been recoded for more speed.  WARNING: when
    continuing from a save file created in stage 2 by a previous prime95
    version, this version will restart stage 2 from the beginning.  ALSO:
    the stage 2 P-1 save file format has changed - in dual boot scenarios
    you must upgrade mprime and prime95 at the same time.

New features in Version 23.2 of prime95.exe
-------------------------------------------

1)  Further performance improvements in the SSE2 code.  You can expect about
    a 5% improvement in LL tests on a P4.

New features in Version 23.1 of prime95.exe
-------------------------------------------

1)  Big SSE2 FFTs now take the L2 cache size into account.  P4 Celeron (128KB
    L2 cache) is faster for FFTs between 512K and 2M.  P4 Northwood (512KB
    L2 cache) is faster for FFTs larger than 1M.
2)  Benchmark no longer times 256K and 320K FFTs, but does time 2048K FFT.
3)  Support for torture testing FFT sizes from 1280K to 4096K added.
4)  A 900 MHz P-III is now required to get first time LL tests by default.
5)  Slightly faster SSE2 FFTs for lengths of 5*2^N and 7*2^N (e.g. 640K, 896K).

New features in Version 22.13 of prime95.exe
--------------------------------------------

1)  A P-1 and ECM QA suite was implemented.  A bug in ECM for exponents
    below 172,700 and near the limit of an FFT size and using SSE2 code
    was fixed.

New features in Version 22.12 of prime95.exe
--------------------------------------------

1)  A bug was fixed that caused some factors to be missed in stage 2 of P-1
    when the available memory did not let the program allocate 12 temporary
    variables.  If testing a number in the 16 millions using an FFT size of
    768K, then each temporary takes 768K * 8 bytes or 6MB.  If your memory
    setting was less than 72MB (6MB * 12 temporaries) then you were affected
    by the bug.  Actual the program allocates some fixed tables so anything
    less than about 75MB triggered the bug.

New features in Version 22.11 of prime95.exe
--------------------------------------------

1)  A bug that caused factors to be missed in the last stage of P-1 and ECM
    factoring was fixed.  The bug was introduced in executables built after
    Sept. 28, 2002.

New features in Version 22.10 of prime95.exe
--------------------------------------------

1)  When running a double-check assignment the preferred trial factoring
    depth is reduced one bit.  This is done because finding a factor will
    save one LL test instead of the usual two LL tests.
2)  On a Windows NT/2000/XP system, if prime95 is run by a user without
    administrator privileges then prime95 cannot install itself as a service.
    Thus, the Start at Bootup option will set prime95 to run at login time
    rather than bootup time.
3)  A crash bug when selecting "Start at Bootup" on Windows NT3 and Windows NT4
    systems was fixed.
4)  Bug in starting more than one prime95 as NT services on multi-processor
    machines was fixed.

New features in Version 22.9 of prime95.exe
-------------------------------------------

1)  Error rate for a clean run is now estimated at 1.8% raising your chances
    of finding a Mersenne prime while double-checking.
2)  You can now stop and continue testing from the system tray menu.
3)  You can now pause prime95 when another program starts running.  See the
    PauseWhileRunning option in undoc.txt.
4)  Fixed bug introduced in 22.8 where No Icon did not work if Start at Bootup
    was also specified in Windows 98.
5)  A bug in unscrambling the proxy server password in primenet.ini was fixed.

New features in Version 22.8 of prime95.exe
-------------------------------------------

1)  Soft FFT crossovers have been implemented.  If you test an exponent that
    is within 0.2% of the old hard FFT crossover point, then 1000 test
    iterations are run to determine if the smaller or larger FFT is
    appropriate for the exponent.  Although not recommended, you can adjust
    prime95's behavior to be more aggressive using the SoftCrossover and
    SoftCrossoverAdjust features discussed in undoc.txt.
2)  To better stress main memory, the torture test will now use up to the
    amount of memory specified in the Options/CPU dialog box.
3)  Iterations with roundoff checking are a little faster for non-SSE2 CPUs.

New features in Version 22.7 of prime95.exe
-------------------------------------------

1)  Trial factoring above 2^64 on a P4 now uses the SSE2 instructions.
    This is more than four times as fast as the previous version.
2)  Old Advanced/Factoring save files are not compatible with this version.
    They are named p0000000 and should be deleted.  This should not be a
    problem as no one should be using this obsolete and unsupported feature.
3)  Four more x87 FFT crossover changes as suggested by Brian Beesley's
    research.
4)  You can now change the NT/2000/XP service name and service display name.
    See undoc.txt for details.
5)  Bug where found factors were silently truncated to 200 digits was fixed.

New features in Version 22.6 of prime95.exe
-------------------------------------------

1)  The Start At Bootup option now runs prime95 as a Windows NT/2000/XP
    service!!  Normally Windows NT/2000/XP will not run GUI programs as
    services, but several tricks have allowed us to get this working
    almost flawlessly.
2)  To reduce spurious error reports on x86 LL tests near the crossover
    points, the program now allows roundoff errors less than 0.40625
    rather than less than 0.4.

New features in Version 22.5 of prime95.exe
-------------------------------------------

1)  A bug in P4 roundoff error recovery was fixed.  Bug was present in
    version 22 executables dated between May 22 and June 18.
2)  Prime95 now properly detects if the program is running by another
    logged in Windows XP user.
3)  When Tray Icon or Hide Icon is set, the "X" in the upper right corner
    no longer closes prime95 rather it minimizes it.  Also right clicking
    the tray icon now brings up a popup menu.
4)  Changed the way prime95 shuts down.  Logoff in WinXP used to hang.

New features in Version 22.4 of prime95.exe
-------------------------------------------

1)  A little more tweaking of the FFT crossovers.
2)  A GCD hang bug was fixed in case where there were a large number of
    entries in the lowm.txt file.  Another GCD bug affecting ECM on F18
    was fixed.

New features in Version 22.3 of prime95.exe
-------------------------------------------

1)  Given more data, the roundoff error checking is now done on every
    iteration for exponents within 0.5% of the maximum that can be tested
    by the current FFT length.  If a roundoff error above 0.4 occurs,
    then the iteration is now repeated without any change to the shift count.
    It now takes a roundoff error greater than 0.6 to corrupt the results.
2)  Many of the FFT ranges have changed.  Version 21 was too aggressive
    in choosing FFT sizes for the P4.  The new handling of roundoff
    errors above 0.4 lets us be more aggressive with the non-P4 code.
3)  Result lines are now WYn rather than WXn.
4)  A crash bug affecting P-1 and ECM using the 2^N+1 option for large N was
    fixed.
5)  A rare memory corruption and possible crash bug in the GCD code was
    fixed.
6)  The -t command line argument will run the torture test.
7)  To reduce wild fluctuations in the RollingAverage, it will be updated
    roughly twice per day.

New features in Version 22.2 of prime95.exe
-------------------------------------------

1)  Factoring assignments go to machines slower than a 233 MHz Pentium.
    Double-checks are assigned machines slower than a 500 MHz P-III.
2)  The speed of the GCD has been improved.
3)  Some of the P4 FFT ranges have changed.  Version 21 was too aggresive
    in choosing FFT sizes for the P4.
4)  Roundoff error checking is now done on every iteration for exponents
    within 2% of the maximum that can be tested by the current FFT length.
    See undoc.txt for ways to disable this new feature.
5)  The previous version would get into an infinite loop if a repeatable
    roundoff error larger than 0.48 was discovered.  Now if a repeatable
    roundoff error greater than 0.45 is found, then the iteration is
    repeated after shifting the FFT data.

New features in Version 22.1 of prime95.exe
-------------------------------------------

1)  Some bugs in error handling when communicating with the server have
    been fixed.
2)  Communicating with the server by RPC is no longer supported.  The
    HTTPNET.DLL and RPCNET.DLL have been deleted.  Only "Basic" Proxy server
    authentication is supported.  Version 21 may have supported MS Proxy
    Server 2.0's NTLM (NT Lan Manager) challenge/response authentication.
3)  The program now uses a high resolution timer rather than the RDTSC
    instruction to time events.  This should help the program display accurate
    timings on laptops with SpeedStep or desktops that can hibernate.  You can
    force the program to use the old RDTSC timing method with the RdtscTiming
    option described in undoc.txt.
4)  The program uses a updated algorithm to automatically detect CPU type and
    speed.  The Options/CPU dialog box no longer let's you set this
    information.  Instead, the Options/CPU dialog displays the detected
    CPU type and speed.  This new feature helps prevent incorrect settings
    when users upgrade or try several overclocking speeds.  If the new
    algorithm fails, you can overide the settings as described in undoc.txt.
5)  Benchmark now writes the program version, timing methodology, cpu type
    and speed, L1 and L2 cache information to results.txt.  It will refuse to
    benchmark if rdtsctiming is 10.

New features in Version 21.4 of prime95.exe
-------------------------------------------

1)  Exiting the Torture Test now prints out how long it ran.
2)  P4 error checking was relaxed slightly to reduce false alarms.

New features in Version 21.3 of prime95.exe
-------------------------------------------

1)  The program will now skip the P-1 factoring stage if another user has
    already performed this step.
2)  The Advanced/Quit GIMPS menu choice now lets you quit after current
    work completes or quit immediately.
3)  A bug was fixed in the error recovery code.  After getting a "Disregard
    last error" message, the user was treated to a new error on every
    iteration.  The end result was incorrect.  The bug only affected the
    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.
4)  You can now switch between HTTP-based and RPC-based PrimeNet protocols
    from the Test/Primenet dialog box.

New features in Version 16.4 of prime95.exe
-------------------------------------------

1)  Lucas-Lehmer testing output now shows percent complete.
2)  Windows NT users can now set processor affinity on multi-CPU systems.
3)  ECM factoring is available for small exponents.  See
    http://www.mersenne.org/ecm.htm for a list of exponents that
    need factoring.
4)  A bug that prevented 486 & Cyrix machines from factoring above 2^62
    has been fixed.
5)  The LockUserInfo feature no longer sends user info every time prime95
    starts up.
6)  A bug in setting minimized or maximized window in a shortcut to prime95
    is fixed.
7)  Test/Status now shows expected completion dates.


New features in Version 16.3 of prime95.exe
-------------------------------------------

1)  The LockUserInfo=1 setting is now sent to the server so that no
    member of a team can accidentally transfer the credit for work
    previously performed by the team.

New features in Version 16.2 of prime95.exe
-------------------------------------------

1)  Bug in calculating estimated time to factor a number has been fixed.

New features in Version 16.1 of prime95.exe
-------------------------------------------

1)  Prime95 can now test exponents up to 20.5 million.
2)  Prime95 can now find factors up to 2^64.
3)  The program now reports to the PrimeNet server new completion dates
    every 28 days (actually user adjustable from 1 to 60 days).  This will
    improve the reclaiming of exponents that are not being actively tested.
4)  The program now reports the current iteration number to the server
    for more informative status reports.
5)  Intermediate files are now less likely to fail.  If an error occurs
    during the writing of an intermediate file, the program continues on
    trying to write the intermediate file every 10 minutes.
6)  A bug in the rolling average code has been fixed.  Prime95 now modifies
    the rolling average when factoring too.
7)  The prime.log file is now limited in size to 256K bytes.
8)  The user information dialog box now has a checkbox to tell the server
    not to send email.
9)  Setting LockUserInfo=1 in prime.ini will make the user information
    dialog box inaccessible.
10) Trying to run a second copy of prime95 will now start the already
    running copy of prime95.  This makes the Hide Icon feature a bit more
    useful.

New features in Version 15.4 of prime95.exe
-------------------------------------------

1) Quit GIMPS choice moved to the Advanced Menu (so novice users do
   not confuse it with exit).
2) A bug in httpnet.dll was fixed.  It now works for even more
   proxy servers and firewalls.

New features in Version 15.3 of prime95.exe
-------------------------------------------

1) More errors in detecting whether you are connected to the Internet have
   been fixed.
2) Minor bugs fixed.

New features in Version 15.2 of prime95.exe
-------------------------------------------

1) A new primenet.dll that uses HTTP to communicate with the server is
   available.  This should allow prime95 to work in environments that
   have firewalls installed.
2) An option that allows you to write a progress line to the results file
   every N iterations is available.
3) A dialog box lets you tell prime95 when you go on vacation.  This
   will prevent the server from reassigning your exponents when you're
   on an extended vacation.
4) Some errors in detecting whether you are connected to the Internet have
   been fixed.
5) An option for you to initiate all contact with the Primenet server
   is now available (in case I didn't find all the problems mentioned
   in number 4 above!)
6) Support for Windows 95 services has been added.
7) To get Windows 95 service support to work, prime95 now changes its
   working directory to the same directory that prime95.exe is located.
   If you must run prime95 from a different directory than the rest of the
   files, then use new -W switch.

New features in Version 15.1 of prime95.exe
-------------------------------------------

1) Better support for dial-up users to the Internet.
2) Prime95 no longer contacts the PrimeNet server at startup.
3) Prime95 will no longer let you select Pentium Pro or Pentium CPU type
   unless your CPU supports the process-specific instructions.
4) Bug where AMD-K6s were using the Pentium Pro factoring code (and
   crashing because of it) is fixed.

New features in Version 15.0 of prime95.exe
-------------------------------------------

1)  Prime95 can now contact a central server to get exponents to test,
    report results, and change your email address.  No database is required!
    The old manual reservation system is still supported.
    This has led to a major reworking of the user interface.
    See the readme file for more details.
2)  The Pentium factoring code (up to 60 bit factors) is about 4.5% faster.
3)  You can now change how often prime95 saves intermediate files to disk.
4)  You can now select one save file or two.
5)  The auto-continue option is gone.  The program now does an auto-continue
    by default.
6)  -Q switch removed.  The preferences dialog box lets you select whether
    the program should be quiet if a new Mersenne prime is found.
7)  -H switch removed.  Use the Hide Icon menu choice instead.
8)  -P switch removed.  The advanced menu now has a dialog box
    that lets you change the priority.
9)  -A switch added.  This allows you to run multiple copies of prime95
    from the same directory.  This is useful on multi-processor machines.
10) Prime95 no longer uses a prime95.ini file in the Windows directory.
    All information is kept in 3 local ini files:  prime.ini, local.ini,
    and worktodo.ini.  Eventually, all ports to other operating systems
    will use these same ini files.
11) The CPU dialog box now has an entry for the AMD K6 and an entry
    for how many hours per day you expect to be running the program.
12) The time estimate in the Status dialog box now takes into account
    the time you've invested in the current Lucas-Lehmer test.  It also
    takes into account how many hours per day you are running the program.
    It also adjusts its time estimate if your computer seems to be running
    faster or slower than expected.
13) Timestamps in the results.txt file.  
14) The results file is now named results.txt, not results.  

New features in Version 14.3 of prime95.exe
-------------------------------------------

1)  The Pentium Pro factoring code is nearly twice as fast compared
    to version 14.2.

New features in Version 14.2 of prime95.exe
-------------------------------------------

1)  Corrected floating point round-off bugs in the factoring code that
    affected testing factors larger than 2^59.
2)  The Pentium factoring code is 5-10% faster.
3)  When an error is detected the program now waits 5 minutes before
    restarting from the last save file.
4)  The detection of corrupt save files has improved.
5)  The Advanced/Time feature now displays the estimated time to test
    an exponent.

New features in Version 14.1 of prime95.exe
-------------------------------------------

1)  The Pentium factoring code is 5% faster.

New features in Version 14.0 of prime95.exe
-------------------------------------------

1)  The program can now check exponents up to 5.26 million!  To test
    these big exponents, you will need a new database and great patience.
2)  The per-iteration error checking code has been improved.  It will
    detect more errors and automatically restart from the previous save
    file.
3)  Options/Tray Icon can be used to have prime95 occupy just a small
    part of the taskbar.
4)  Options/No Icon can be used to have prime95 removed from the taskbar.
    Read the warnings in the readme file before using this feature.
5)  Options/Preferences now has a checkbox to let you send results to
    a file called "results.txt" rather than "results".
6)  Options/CPU now has a Cyrix checkbox.  There is no Cyrix-specific
    code.  This change provides better estimates in Range/Status.
7)  Options/Torture Test runs a continuous Self Test.  This is great
    for "burning in" a new machine.
8)  The Round-off checking menu choice (which should be turned off)
    was moved to the Advanced menu.
9)  The estimates in Range/Status have been changed slightly.  Hopefully,
    these new estimate are a little more accurate.
10) The Options/Self Test option now takes nine hours.

New features in Version 13.2 of prime95.exe
-------------------------------------------

1)  Minor adjustments made to the per-iteration error checking code.
    It was occasionally raising a FATAL ERROR when it should not have been.

New features in Version 13.1 of prime95.exe
-------------------------------------------

1)  Faster!  Prime now supports a wider variety of FFT run lengths.
    This means Lucas-Lehmer tests on exponents between 1.33M and 2.33M
    will be 13 to 40% faster.

New features in Version 12.4 of prime95.exe
-------------------------------------------

1)  A minor bug in the Pentium factoring code has been fixed.
2)  When creating an intermediate file, instead of deleting the previous
    intermediate file it is renamed just in case there is a machine crash
    before the new intermediate file is written to disk.
3)  Factoring is now 6% faster.
4)  The program is now "network-enabled".  See network.txt for more details.

New features in Version 12.3 of prime95.exe
-------------------------------------------

1)  The -h command line argument is now available.

2)  Save files are generated every half-hour when factoring.

New features in Version 12.2 of prime95.exe
-------------------------------------------

1)  A minor bug in the factoring code has been fixed.

New features in Version 12.1 of prime95.exe
-------------------------------------------

1)  Command line arguments are now available to help you run the program
    on your co-worker's machines!


New features in Version 12 of prime95.exe
-----------------------------------------

1)  The program is faster!  Expect to see improvements of 8 to 15%.
    The faster your CPU, the more improvement you should notice.
    The program also uses less memory.
2)  There are now 5 separate hour-long self tests - one for each
    possible FFT length.  You will run one of the new one-hour
    self tests even if you passed the self test in the previous version.
3)  The program can now test exponents as high as 2,630,000!
4)  The user interface has changed.
	a) You no longer enter a 3 or 4 digit range.  Rather you enter
	   an explicit starting and stopping point.  For example, in
	   the previous version you would enter 1234 for the range.
	   In this version you enter a starting point of 1234000 and
	   an ending point of 1234999.
	   This makes it much easier to "check out" just part of a range.
	   It also makes it easier to split a range among two or more
	   machines.
	b) The "Only Find Factors" checkbox has been replaced.  Use
	   the Range / Factor menu choice instead.
	c) The Range / Double Check menu choice has been added for those
	   of you who are double checking previously checked exponents.
	d) The Advanced / Password menu choice is now used to activate
	   the rest of the Advanced menu.
5)  The program now performs two new error checks every iteration!  These
    will help guard against memory errors or "cosmic ray" errors.
    These new checks will not catch all such problems but should catch the
    vast majority.


New features in Version 10 of prime95.exe
-----------------------------------------

1)  The program will now undergo an hour long self-test before
    running any Lucas-Lehmer tests in your selected range.
    This self-test is also available from the menus.  You might
    want to run this when you install new hardware or device
    drivers.
2)  You can now get a status report on your range.  Choose Range
    Status from the menus to get a report on the number of Mersenne
    numbers left to test, expected time to completion, etc.  This
    information is also displayed whenever you choose a new range
    with Range Start or Range Next.
3)  The File menu has been renamed Range - it seems clearer to beginners.
4)  The Advanced menu has been disabled.  You must read the readme.txt
    file to learn how to activate it.  This is designed to keep novice
    users out of trouble.  There is no reason, other than curiosity, for
    you to use any of the Advanced menu choices.
5)  A bug in stopping and continuing when factoring in Version 8 has
    been fixed.


New features in Version 8 of prime95.exe
----------------------------------------

1)  Factoring speed has been doubled for Pentiums.  486 machines will
    notice a 15% improvement when factoring.
2)  The program will now automatically determine your CPU type and speed.
    This information is used in choosing the optimal factoring algorithm.

