A software emulator for parallel random access machine (PRAM)
 is available at anonymous ftp site
  
     cs.joensuu.fi (128.214.14.19) 
  
 in directory
  
     /pub/pram
  
 Files
 
     emulator.tar.Z 
 
 in the above directory are compressed tar files containing the ANSI C 
 source code and the documentation in postscript form of the PRAM emulator.
 
 
 PRAM Emulator
  
 The PRAM model used is the following:
 A PRAM consists of P processors, an 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. The instruction set includes simple arithmetic and
 bitwise operations, conditional and unconditional jumps, shared memory
 read and write instructions, register-to-accumulator and accumulator-to-
 register data transfer instructions, and a halt instruction. All the 
 models EREW, ERCW, CREW, and CRCW and the CW variants WEAK, COMMON, 
 TOLARANT, COLLISION, COLLISION+, ARBITRARY, and PRIORITY are supported.
  
 The implementation places no fixed limits for the number of processors or  
 the number of registers. These and the size of the shared memory are, of 
 course, limited by the size of the memory space of the platform.
  
 The emulator is controlled with a simple assembly style language derived
 from the PRAM instruction set. The emulator system contains an assembler
 that converts a text form program to an easy-to-interpret binary form.
 The emulator program itself gets the binary form program as input. The 
 emulator contains an interactive monitor program for interactive 
 monitoring of the execution of the emulator.
  
 The emulator can be installed and used if an ANSI C compiler and a curses 
 terminal screen handling package are available. (At least curses packages 
 in UNIX systems and the public domain PDCurses should work. The emulator 
 can be changed to work without the curses package -- and without the
 interactive monitoring facility :-( -- with some programming effort.) 
 The language used to control the emulator is designed to be preprocessed 
 with a C preprocessor (cpp or equivalent). So, it is desirable that 
 a C preprocessor is available, but the preprocessor is not absolutely 
 necessary. (If the emulator is used to execute programs produced by the
 parallel modula-2 compiler then preprocessor is necessary because the
 output of the compiler contains macros etc.; when writing pram programs
 by hand the need for preprocessing can be avoided by not using macros,
 comments, file inclusion, or other nice preprocessor features.)
  
 Happy emulations! Comments are welcome.
  
 Pasi Hamalainen, University of Joensuu, FINLAND
 email: phamal@cs.joensuu.fi