The x-coordinate is a hardware coordinate from 0 to 448. Since the Amiga is only capable of performing this test every four screen points, this coordinate is rounded to the nearest multiple of four.
The y-coordinate can be any value from 0 to 312. Normally, coordinates from 256 to 312 require special programming, but AMOS Professional generates the correct instructions automatically, so there is no need for concern! Here are some examples:
X> Cop Wait 0,130: Rem Wait for screen to reach hardware coords 0,100 Cop Wait 0,300: Rem Wait for line 300 Cop Wait 12,10: Rem Wait for coordinates 12,10 to arrive
The optional xmask and ymask parameters are bit-mask values which allow for a pause until the screen coordinates satisfy a specific combination of bits. The default value is $1FF. For example:
X> Cop Wait 0,2,$1FF,%11 : Rem Await next EVEN scan line
instruction: re-set copper list pointer
This command is used to add a pair of MOVE commands, forcing the copper list to re-start from the very first instruction. This may be used to generate simple loops.
instruction: swap logical and physical copper lists
The COP SWAP command switches over the logical and physical copper lists. The new copper list will now be flicked into place, and the results will be shown after the next vertical blank period. For example:
X> Cop Swap : Wait Vbl
instruction: give address of logical copper list
This command returns the absolute address of the logical copper list in memory. It can be used to manipulate the copper list directly from AMOS Professional Basic. Lists can also be generated by using assembly language.