1. A computer program product for executing a machine instruction, the computer program product comprising: a non-transitory computer readable storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising: obtaining, by a processor, a machine instruction for execution, the machine instruction being defined for computer execution according to a computer architecture, the machine instruction comprising: an opcode field to provide an opcode, the opcode to identify a perform pseudorandom number operation; and a register field to be used to identify a register, the register to specify a location in memory of a first operand to be used by the machine instruction; and executing the machine instruction, the executing comprising: obtaining a function code from a register associated with the machine instruction, the function code to specify a function to be performed; obtaining, based on the function code being a particular value, a modifier (M) field of the register associated with the machine instruction; based on the M field having a first value, performing a deterministic pseudorandom number generate operation, the deterministic pseudorandom number generate operation comprising: for each block of memory of one or more blocks of memory of the first operand, generating a hash value using a 512 bit secure hash technique and at least one seed value of a parameter block of the machine instruction, wherein the parameter block is located using another register associated with the machine instruction; and storing at least a portion of the generated hash value in a corresponding block of memory of the first operand, the generated hash value being at least a portion of a pseudorandom number.