Command: mem_copy
  
Syntax: 
  mem_copy(a1, a2, i)
  
Description: 
  Copy a block of i bytes of memory from address a2 to address a1. 
  
Comments: 
  The bytes of memory will be copied correctly even if the block 
  of memory at a2 overlaps with the block of memory at a1.
  
  mem_copy(a1, a2, i) is equivalent to: poke(a1, peek({a2, i})) 
  but is much faster.
  
Example: 
     dest = allocate(50)
              src = allocate(100)
              poke(src, {1,2,3,4,5,6,7,8,9})
              mem_copy(dest, src, 9)
 
See Also: 
  mem_set, peek, poke, allocate, allocate_low
  
