+ 000xxx - reserved
+ 001xxx - print functions
+ 1000 ----- print string from stack (stdio.pvvs)
+ 1001 ----- print string from heap (stdio.pvvs)
+ 1010 ----- print number from stack (stdio.pvvs)
+ 010xxx - math functions
+ 10000 ----- random (math.pvvs)
+ 10001 ----- absolute value (math.pvvs)
+ 011xxx - heap functions
+ 11000 ----- memset (heap.pvvs)
+ 11001 ----- memcpy (heap.pvvs)
+ 11010 ----- memrand (heap.pvvs)
+ 11011 ----- memcmp (heap.pvvs)
+ 11100 ----- memsrch (heap.pvvs)
+ 11101 ----- <empty>
+ 11110 ----- slurp (heap.pvvs)
+ 11111 ----- spew (heap.pvvs)
+ 100xxx - string functions
+ 100000 ----- strlen (string.pvvs)
+ 101xxx - unassigned
+ 110xxx - conversion functions
+ 111xxx - debug functions
+ 111000 ----- dump heap (debug.pvvs)
+ 111001 ----- dump stack (debug.pvvs)
+ 1xxxxxx - reserved for less common entry points
+ 1000000 ----- slurp registers (heap.pvvs)
+ 1000001 ----- spew registers (heap.pvvs)
+ 1000010 ----- print sign of number (stdio.pvvs)
+ 1000011 ----- print magnitude of number (stdio.pvvs)
+ 1000100 ----- print string from stack (stdio.pvvs)
+ 1000101 ----- print string from heap (stdio.pvvs)