# Download Prime95 30.19

The distributed computing project Gimps, which stands for Great Internet Mersenne Prime Search, searches for Mersenne prime numbers. These are prime numbers that are exactly one smaller than a power of two, or 2n – 1. The first four n numbers to form the first four Mersenne prime numbers are 2, 3, 5 and 7, where 3, 7, 31 and 127 come out. The required program is called Prime95 and is listed under a own license released. Version 30.19 build 13 has been released for FreeBSDLinux (32-, 64bit) and Windows (32-, 64bit); Of course you can also use the source code fishing in. The announcement and list of improvements look like this:

**Prime95 version 30.19 released**

Version 30.19 is now available. ECM stage 2 is now much faster if you can give prime95 lots of memory to use. This is similar to the improvements to P-1 stage 2 in version 30.8. There are other minor bug fixes and tweaks. This is not a required upgrade — version 30.3 and later can be used to hunt for new Mersenne primes. Should you decide to upgrade, if any workers are currently in ECM or P-1 stage 2 wait for ECM or P-1 to finish before upgrading. If you have any upgrade questions, ask in this thread at Mersenne Forum.

**New features in Version 30.19 of prime95.exe**

- Edwards ECM curves. Given a reasonable amount of memory, Edwards ECM curves are roughly 10% faster than Montgomery ECM curves used in all earlier prime95 versions.
- Added support for running ECM stage 2 given a resume file from GMP-ECM. Especially useful when GMP-ECM uses a GPU to run ECM stage 1. Syntax for worktodo entries are:

ECMSTAGE2=k,b,n,c,filename[,B2-or-zero][,skip_curves][,num_curves][,”known-factors”]

ECMSTAGE2N=filename[,B2-or-zero][,skip_curves][,num_curves][,”known-factors”] - New timestamp options in undoc.txt.
- Manual communication menu choice will also start proof uploads.
- From the Test/Primenet… dialog box, turning on Use Primenet will bring up the Test/Worker Windows… dialog box to allow changing work preferences prior to contacting the PrimeNet server.
- The P-1 and ECM stage 2 vs. stage 1 runtime estimate used for optimal B2 calculations is now compared to the actual so that future estimates will hopefully be more accurate.
- Advanced/Test now creates a PRP worktodo.txt entry for large exponents.

**New features in Version 30.18 of prime95.exe**

- Faster generic mod. This is more useful for programs like PFGW than prime95.

**New features in Version 30.16 – 30.17 of prime95.exe**

- Smaller executable. Many SSE2 FFTs optimized for CPUs made before 2010 were removed. These CPUs will still be able to run all FFT sizes, but 30.15 might have a more efficient implementation available.

**New features in Version 30.11 – 30.15 of prime95.exe**

- Settings are no longer stored in local.txt. Settings are automatically moved to prime.txt. In addition, settings within prime.txt are now organized into several sections for enhanced readability.

**New features in Version 30.9 – 30.10 of prime95.exe**

- ECM stage 2 using fast polynomial multiplication similar to the GMP-ECM program. If lots of memory is available for stage 2 this implementation will be substantially faster.
- Proof files start uploading within a minute of sending a PRP result to the server. Previously it could take up to an hour for proof uploading to begin.
- Worktodo.add files are now processed without stopping all workers.
- Settings from local.txt have been moved to prime.txt. Settings in prime.txt grouped for clarity.

**New features in Version 30.8 of prime95.exe**

- P-1 stage 2 using fast polynomial multiplication similar to the GMP-ECM program. If lots of memory is available for stage 2 this implementation will be substantially faster.

**New features in Version 30.7 of prime95.exe**

- Better prime pairing in stage 2 or ECM/P-1/P+1. This usually results in slightly better stage 2 timings or less memory used. Save file formats changed – upgrading to 30.7 while ECM/P-1/P+1 work is in stage 2 will result in stage 2 being restarted from scratch.
- P-1 converted to use P+1 style stage 2. From the users perspective there is no difference. Internally a modular inverse is required at stage 2 init, but there is one multiplication saved for every D-block processed. For all common P-1 cases, this is a little faster.
- ECM/P-1/P+1 no longer use a bit map for prime pairs. Instead a compressed pairing folder is created to save memory. For large B2 values this also results in fewer calls to generate pairing maps. It also makes stage 2 save files smaller.
- Some minor changes in AVX-512 FFT crossovers. ECM/P-1/P+1 all changed to rollback to the last saved file and switch to a larger FFT size should an excessive roundoff error be encountered.
- Support for asymmetric processor architectures such as Intel's Alder Lake.
- Torture test dialog now asks for number of cores to test along with a “Use hyperthreading” checkbox. Previously, the dialog box asked for total number of torture threads to execute.
- Versions 30.4/30.5/30.6 were underestimating the cost of P-1 stage 2 relative to P-1 stage 1. Expect this version to use lower stage 2 bounds in P-1.

**New features in Version 30.6 of prime95.exe**

- P+1 factoring. A worktodo.txt entry looks like this:

Pplus1=k,b,n,c,B1,B2,nth_run[,how_far_factored][,”known_factors”]

Unlike P-1, the fact that factors of Mersenne numbers is 1 mod 2p is of no value. Thus, P-1 is vastly more effective at finding factors. A P+1 run is about as valuable as running one ECM curve. P+1 stage 1 is 50% slower than P-1 stage 1 but several times faster than ECM stage 1. P+1 stage 2 is a little faster than P-1 stage 2 which in turn is a little faster than ECM stage 2 Unlike P-1, P+1 has only a 50% chance of finding a factor if factor+1 is B1/B2 smooth. Thus, it makes sense to do 1 or 2 (maybe 3) runs. That's what the nth_run argument is for. There are two special starting values for P+1 that have a slightly higher chance of finding a factor. These special starting values correspond to nth_run=1 and nth_run=2. Like P-1, if how_far_factored is specified, prime95 will ignore B2 and calculate the best B2 value for the given B1. - Faster ECM stage 1 when factoring exponents near the limit of an FFT size.
- Gwnum library new functions give a programmer more tools to reduce normalized adds. A tutorial.txt file (download the prime95 sources) is now available to help a programmer use the gwnum library.

**New features in Version 30.4/30.5 of prime95.exe**

- Faster P-1 stage 2.
- Faster ECM stage 1 and stage 2.
- Gwnum library overhauled. Many functions deprecated. Replaced by more powerful gwmul3. New functions that compute (a+b)*c and (ab)*c with less memory accesses. Faster conversion to and from binary.
- ECM and P-1 can find the best B2 value for the amount of memory prime95 is allowed to use. For ECM, this happens when the worktodo.txt line sets B2=100*B1 which is the default assignment from the PrimeNet server. For P-1, the best B2 is chosen when the worktodo.txt line specifies the trial factoring depth. For example, “Pminus1=1.2,20000003,-1.500000,0.70” chooses the best B2 bound for B1=500000 given that M20000003 has been trial factored to 2^70.

Version number | 30.19 |

Release status | Final |

Operating systems | Windows 7, Linux, BSD, macOS, Windows Server 2012, Windows 10, Windows Server 2016, Windows Server 2019, Windows 11 |

Website | GIMPS |

Download | https://www.mersenne.org/download/ |

License type | Prerequisites (GNU/BSD/etc.) |