The Free On-line Dictionary of Computing (30 December 2018):

parallel random-access machine

    (PRAM) An idealised parallel processor consisting
   of P processors, unbounded shared memory, and a common
   clock.  Each processor is a random-access machine (RAM)
   consisting of R registers, a program counter, and a
   read-only signature register.  Each RAM has an identical
   program, but the RAMs can branch to different parts of the
   program.  The RAMs execute the program synchronously one
   instruction in one clock cycle.

   See also pm2.

   (1997-06-04)