anchor.diff:  \	+6	checksum
   \ The checksum over the whole structure must equal $FFFF.
   \ 
  -\ findTag's parameters are as follows:
  -\	+0	Return PC
  -\	+1	Start address (must be even)
  -\	+2	End address (must be even)
  -\ Upon success, it returns:
  -\	+3	Address of tag
  -\	+4	0
  -\ Otherwise:
  -\	+3	undefined
  -\	+4	Reason code (non-zero)
  +\ To use, load fndtagsta with the starting address to check for, and fndtagend with the largest address to check.
  +\ If findTag succeeds, rsn will be 0, and fndtagsta will point to the tag found.  Otherwise, fndtagsta will be
  +\ undefined (usually, but not guaranteed to be, the same as fndtagend) and rsn set to indicate why.
   
   int, fndtagend
   int, fndtagsta
  
positive.code: 	then,
  	ENOTFOUND rsn !, ;,
  
  \ fmtmem formats a memory pool with the required metadata to support allocation requests.
  \ Arguments:
  \	+0	Return PC
  \	+1	Start of pool (must be even)
  \	+2	Size of pool
  \ No returns.
  \ 
  \ Beware: formatting a pool that's been previously used will, in effect, forcefully de-
  \ allocate everything from that pool.
  
negative.code: 
  \ Global state for all OS services.
  
  :, halt,	again, ;,
  :, crash	$C000 #, !,  $C000 #, @, -1 #, xor, $C050 #, !,  $AAAA #, $C0A0 #, !, ;,
  :, 0=		if, 0 #, exit, then, -1 #, ;,
  
  \ rsn stores the reason for a service's failure to deliver the expected results.
  \ Numerous system calls can fail for a number of reasons.  See the errors.fs file
  \ for a list of reasons and their most common circumstances.
  int, rsn
  
  \ fillRect draws very simple rectangular patterns on the screen.
  \ This can be used to clear the screen, or to let the user in on the current progress of something.
  