CopyToVDP:
; Copies data to the VDP
; Parameters: hl = data address, bc = data length
; Affects: a, hl, bc
-:  ld a,(hl)    ; Get data byte
    out (VDPData),a
    inc hl       ; Point to next letter
    dec bc
    ld a,b
    or c
    jr nz,-
    ret