The Oberheim Matrix 1000 is an MC6809-based synthesiser that is just begging to be reverse engineered.

http://www.vintagesynth.com/oberheim/mat1000.php

https://github.com/8BitPimp/OberheimMatrix1000

DASMx is a disassembler for a range of common microprocessors.

http://myweb.tiscali.co.uk/pclare/DASMx/

This page have been made to give general information about Motorola's 6809 and Hitachi's 6309 mikroprosessors: instructions, emulators, tools, debuggers, disassemblers and assemblers.

Includes Arto's DASM09 disassembler

http://atjs.mbnet.fi/mc6809/

Based on Arto Salmi's C core that can be found somewhere on the 'net I built a complete 6800/6809/6309 disassembler that can handle input files in a variety of formats (Intel Hex / Motorola S09 / Flex9 Binary / Binary). Since disassembly without guidance produces measly results, it can load information files with quite a lot of directives, too.

https://github.com/Arakula/f9dasm

Radare is a portable reversing framework

http://radare.org/r/

Gareth is working on a 6809 plugin for radare2 specifically for this project.

0x0000
    I/O*
    U819: {
    0x0000 T1*
    0x0400 T2*
    0x0800 T3*
    0x0c00 T4*
    0x1000 DAC
        0x1000
            $ U712 - 74LS374 - DAC HI 7
            b00000001 - DAC 5
            b00000010 - DAC 6
            b00000100 - DAC 7
            b00001000 - DAC 8
            b00010000 - DAC 9
            b00100000 - DAC 10
            b01000000 - DAC 11
            b10000000 - FASTX

        0x1010
            $ U713 - 74HC138 - DAC LO 5
            b00000100 - U715 - 74HC138 - S&H Enable
            b00001000 - DAC 0
            b00010000 - DAC 1
            b00100000 - DAC 2
            b01000000 - DAC 3
            b10000000 - DAC 4

    0x1400 UORV*
        $ U809 - 68850 - UART
    0x1800 SW*
    0x1c00
        U820: {
        0x1c00 L1*
        0x1c20 L2*
        0x1c40 L3*
        0x1c60 MISC*
            $ U818 - 74LS174 - 6bit latch {
                b000001 - VA13
                b000010 - VA14
                b000100 - VA15
                b001000
                b010000
                b100000
            }
        0x1c80 LED1*
        0x1ca0 LED2*
        0x1cc0 LED3*
            (LED1 to 3 are 7-segment displays labelled DISP 1 to 3 respectively. Segment mapping tbd)
        0x1ce0 LED4*
            6 single LEDs {
                0x01 - CHANNEL
                0x02 - UNITS
                0x04 - DATA D
                0x08 - EXT. F
                0x40 - FINE T
                0x80 - PITCH
                (bits 4 and 5 not connected)
            }
        }
    }

0x2000
    $ U803 - 27512 (Patches) {

        Bank Select - VA13, VA14, VA15
    }
The code rom is
0x4000
    $ U802 - 27512 (Expansion) {

        Bank Select - VA13, VA14, VA15
    }

0x6000
    $ U8012B - 43256 {
        RAM
        Bank Select - VA13, VA14
        0x7fff - Initial stack location (set at PC 0x800E)
                 (Bank 0 only?)        
    }

0x8000
    $ U809 - 27256 {
        0x8000 Rom Base (27256)
        0x8003 Reset Handler
        0x84b4 IRQ Handler
        0x85e3 FIRQ Handler (Serial IRQ)
        0xFFF0 Vector Table
    }