Star Battle Expanded Pattern

Star Battle uses the Magic Register's Expander function to pack its fighter patterns in half the ROM space. The XOR function 'merges' the fighter with the background.

; XPAND load (code portions omitted for clarity)
; [...]
L2650:    LD      A,$08         
          OUT     ($19),A       ; write 00001000B to XPAND (foreground color = 10, background = 00)
 
; [...]
 
SYSSUK  WRITP                   ;  UPI WRITe with Pattern size lookup
          DB      $7C           ;  ... X = 124
          DB      $00           ;  ... Y = 0
          DB      $28           ;  ... Magic Register = 0010 1000B (XOR, Expand)
          DW      $26EC         ;  ... Pattern Address
 
; [...]
 
; Small H-Fighter Graphic
L26EC:    DB    10000100B            ;   X . . . . X . .
          DB    10110100B            ;   X . X X . X . .
          DB    11111100B            ;   X X X X X X . .
          DB    10110100B            ;   X . X X . X . .
          DB    10000100B            ;   X . . . . X . .
 
; [...]