+#define A3800_KEYPAD_STROBE 0x04
+#define A3800_DISPLAY_WRITE 0x08
+#define A3800_MOTOR_DATA 0x10
+#define A3800_MOTOR_COL8_ENABLE 0x20
+#define A3800_MOTOR_COL9_ENABLE 0x40
+
+/******* from main.c *******/
+int __attribute__((noreturn)) main (void);
+void __attribute__((interrupt)) rti (void);
+void __attribute__((interrupt)) sci_interrupt_serial (void);
+void __attribute__((interrupt)) sci_interrupt_coinmech (void);
+void __attribute__((interrupt)) uart_interrupt (void);
+
+/* other one liners */
+extern inline bool door_open() { return switch_input & A1800_DOOR_OPEN; }
+extern inline void spi_enable() { bset((void*)&_io_ports[M6811_SPCR], M6811_SPE); }
+extern inline void spi_disable() { bclr((void*)&_io_ports[M6811_SPCR], M6811_SPE); }