SDLSTL, SDLSTH Shadow register of pointer to display list
DLISTL, DLISTH Pointer to display list
SDMCTL Direct Memory Access (DMA) Control
VDSLST Pointer to Display List Interrupt routine
NMIEN to enable the Display List Interrupt
NMIST, NMIRES to check the status of NMIEN
WSYNC halts the CPU until end of scanline
VCOUNT Scanline counter
PENH, PENV horizontal and vertical position of the light pen
LPENH, LPENV shadow register of PENH and PENV
Display List Instruction table
see topic list, VBI Vertical Blank Interrupt
