---------------------------------------------------------- This information is provided to help with board debug, and is not intended to be an attempt to reverse engineer the hardware. Use at your own risk, this information may be incorrect. Source : forgotten, probably schematics, not verified with disassembly. DIG DUG MEMORY MAP ================== -----------+---+-----------------+------------------------- hex |r/w| D D D D D D D D | location | | 7 6 5 4 3 2 1 0 | function -----------+---+-----------------+------------------------- 0000-3FFF | R | D D D D D D D D | CPU 1 rom (16k) 0000-1FFF | R | D D D D D D D D | CPU 2 rom (8k) 0000-0FFF | R | D D D D D D D D | CPU 3 rom (4k) -----------+---+-----------------+------------------------- 6800-680F | W | - - - - D D D D | Audio control 6810-681F | W | - - - - D D D D | Audio control -----------+---+-----------------+------------------------- 6820 | W | - - - - - - - D | 0 = Reset IRQ1(latched) 6821 | W | - - - - - - - D | 0 = Reset IRQ2(latched) 6822 | W | - - - - - - - D | 0 = Reset NMI3(latched) 6823 | W | - - - - - - - D | 0 = Reset #2,#3 CPU 6825 | W | - - - - - - - D | custom 53 mode1 6826 | W | - - - - - - - D | custom 53 mode2 6827 | W | - - - - - - - D | custom 53 mode3 -----------+---+-----------------+------------------------- 6830 | W | | watchdog reset -----------+---+-----------------+------------------------- 7000 |R/W| D D D D D D D D | custom 06 Data 7100 |R/W| D D D D D D D D | custom 06 Command -----------+---+-----------------+------------------------- 8000-87FF |R/W| D D D D D D D D | 2k playfeild RAM -----------+---+-----------------+------------------------- 8B80-8BFF |R/W| D D D D D D D D | 1k sprite RAM (PIC,COL) 9380-93FF |R/W| D D D D D D D D | 1k sprite RAM (VPOS,HPOS) 9B80-9BFF |R/W| D D D D D D D D | 1k sprite RAM (FLIP) -----------+---+-----------------+------------------------- A000 | W | - - - - - - - D | playfield select A001 | W | - - - - - - - D | playfield select A002 | W | - - - - - - - D | Alpha color select A003 | W | - - - - - - - D | playfield enable A004 | W | - - - - - - - D | playfield color select A005 | W | - - - - - - - D | playfield color select A007 | W | - - - - - - - D | flip video -----------+---+-----------------+------------------------- B800-B83F | W | D D D D D D D D | write EAROM addr, data B800 | R | D D D D D D D D | read EAROM data B840 | W | D D D D | write EAROM control -----------+---+-----------------+------------------------- Notes : Audio1,6810 is write control for a 32x4 bit ram that (maybe) controls the sound volume envelope, via IC 2L(4066 cmos switch). This controls a resistive mixing network. Bit0=10k,bit1=2.2k, bit2=4.7k,bit3=100k. Audio0,6800 is write control for a 32x4 ram that controls a multi frequency generator circuit. ----------------------------------------------------------------