Symsyn is a simple syntax, back-to-basics, minimalist programming language which resembles a sort of assembly language for a Pascal Virtual Machine (PVM).  Assemblers provide a one to one relationship between a mneumonic instruction and a hardware opcode. Similarly, Symsyn establishes a one to one relationship between an instruction and a Pascal procedure.  The instruction set is, therefore, open ended and can grow into any operating environment.

It is implemented by a compiler, SSL which generates version specific PVM code from a text file; and a runtime executive/emulator, SSX which processes the code. Both are written in Pascal.  SSX has program (prog) monitoring and log functions. It is capable of running 99 progs concurrently.  Multitasking is enhanced with several inter-program communication instructions which provide synchronization and data passing functions.

The single task runtime SSS is simpler, smaller, and faster than SSX.  It runs from the command line, has no window, no commands, and no log file.  It runs a single prog to completion and then ends.

The intended user is a novice programmer or a non programmer who doesn't have the time or interest to learn the conceptual niceties and abstract concepts of a more advanced and rigorous language, but needs to accomplish a given task. Symsyn's simplicity and potential could provide much of the functionality of Pascal without all of Pascal's discipline and could be an on ramp to learning Pascal.



A compiler and emulator were written for the PC under DOS to enable it to run multitasking software originally written for a minicomputer. The software drove legacy data communications protocols, code translation, encryption support, and transaction flow control for a real time banking application involving ATM's, teller terminals, and regional switches. This front end and a host computer were capable of controlling hundreds of devices.  While Symsyn is decidedly different from that source code, major portions of that compiler and emulator were used here.




As much as possible examples will be used to explain the syntax.  But first, some basic principles.

• A prog consists of one or more instructions.
• One instruction or data declaration per line.
• All data declarations precede instructions.
• Labels start in column one.
• Data and instructions are free form after column one.
• Data items may be declared or just used in instructions.
  
• Instructions consist of a command (opcode) followed by zero or more operands.
• If the first item after the optional label is not a valid command, MOVE is assumed.
  
• Items are separated by one or more spaces.
  
• Action flows from left to right, rightmost item usually receives result.
• Arithmetic is 64 bit.
• Text after '|' on a line is comment.
  
• The prefix '#' means size of.
• The prefix '@' means address of.

There are three data types.

• Word - a 64 bit binary object residing in the program space which can be an Integer or a Real (floating point) variable.  The Integer can be declared as a data item or just used in an instruction.   Bits can be addressed by number.  They are numbered 63 to 0, left to right (msb to lsb).  The Real must be declared by giving it a value with a decimal point.  Either Integer or Real array index begins at 0.
  

• Character String - an unstructured list of one or more characters residing in the program space.  It can be declared as a data item or just used in an instruction as a literal string.  Index begins at 0.
  

• Ansi String - a structured list of characters of any length residing outside the program space. It is never declared. All Ansi String identifiers begin with a '$'.  Index begins at 1.
  

In the following examples, identifiers starting with

• C, D, E, are character strings 
• X, Y, Z, are words
• I, J, K, are index words
• N is a count word (number of characters)
  
• $R, $S, $T, are ansi strings