Non-Maskable Interrupt (i.e., cannot be disabled by the 6502). The Display List Interrupt and the Vertical Blank Interrupt are both NMIs. These can be disabled with the ANTIC NMIEN register.
Non-Maskable Interrupt; used for video display and RESET. NMIs are processed by the ANTIC chip.
on- askable nterrupt. Unlike IRQs, you can't tell the 6502 to ignore this kind of interrupt. DLIs and V BLANK interrupts are both NMIs.