                             DIO Virtual Processor (VP)

DIO in run mode (-run) executes the given input file
as a VP program.

Features of VP:

* Virtual 32 bit RISC processor
* Has a 64 bit FPU
* Multithread support
* Fix 16 bit wide instuctions
  1. byte : Selects the instruction
  2. byte : Parameter of the instruction
* Builtin system calls, library functions

VP registers (32 bit):

  FL   : Flags
         bit0 : Zero
         bit1 : Sign
         bit2 : Carry
         bit3 : Overflow

         bit4: Error
         bit5: Halt
         bit6: multiTask

  IP   : Instruction pointer
  SP   : Stack pointer
  BP   : Base pointer

  Tim  : Time slice (clocks)
  Clk  : Clock (instruction) counter
  Env  : Environment pointer
  Dat  : User data

The main instructions are implemented in OPFN.H/C
and documented in OPFN.TXT.

The real number instructions are implemented in VFPU.H/C
and documented in VFPU.TXT

The system calls are implemented in SYS.H/C
and documented in SYS.TXT.

The library functions are implemented in LIB.H/C
and documented in LIB.TXT.

===========================================================================
