COLOR_GREY1 = 2
COLOR_BLACK = 3
-;-------------------------------------------------------------------------------
; bios zp usage:
-;
-; 06/07 address of character set bitplane 1
-; 08/09 address of character set bitplane 2
-; 0a nmi $4800 echo
-; 0b irq counter
-; 0c nmi call cart nmi
-; 0e/0f/10/11 big endian irq counter
-; 15/16/17 ?/xpos/ypos
-;
-; e8 nmi reset to $ff
-;
-
ZP_NMI_4800 = $0a
-ZP_NMI_ENABLE = $0c
+ZP_IRQ_COUNT = $0b
+ZP_IRQ_CTRL = $0c
+
+ZP_IRQ_CNT1 = $0e
+ZP_IRQ_CNT2 = $0f
+ZP_IRQ_CNT3 = $10
+ZP_IRQ_CNT4 = $11
+ZP_NMI_FLAG = $e8