Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Park Miller random number generator also known as the Lehmer random number generator is a variant of linear congruential generator that operates in multiplicative group of integers modulo n. In 1988, Park and Miller suggested RNG with particular parameters n=231 1 = 2,147,483,647 (a Mersenne prime M31) and g=16,807 (a primitive root modulo M31), now known as MINSTD. Despite that MINSTD was later criticized by Marsaglia and Sullivan, it is still in use today (in particular, in CarbonLib). ZX Spectrum uses the Park Miller RNG with parameters n=216+1 = 65,537 (a Fermat prime F4) and g=75 (a primitive root modulo F4). The CRAY random number generator RANF is a Park Miller RNG with n=248 and g=44,485,709,377,909. Another popular pair of parameters is n=232 5 = 4,294,967,291 and g=279,470,273. The GNU Scientific Library includes several random number generators of the Park Miller form, including MINSTD, RANF, and the infamous IBM random number generator RANDU.