HUMBUG

HUMBUG for the 6809 and 68000 is free for non-commercial use by accepting this agreement.

Commands
  AD   FORMATTED ASCII DUMP
  AI   ASCII INPUT
  AO   ASCII OUT
  BA   BASIC
  BP   PRINT BP LOCATIONS
  BR   SET/RESET BPS
  CO   CONTINUE AFTER BP
  CS   FOUR-BYTE CHECKSUM
  FD   REGULAR DISK BOOT
  FI   FIND BYTES COMMAND
  FM   FILL MEMORY
  HA   COMBINED HEX AND ASCII DUMP
  HD   HEX DUMP ROUTINE
  HE   HELP
  IS   SETUP FDC AND DRIVE DATA
  JS   JUMP TO SYSTEM PROGRAM
  JU   JUMP TO USER PROGRAM
  LO   LOAD S1S9 FORMAT TAPE
  MC   MEMORY COMPARE
  ME   MEMORY EXAMINE
  MO   MOVE MEMORY CONTENTS
  MS   MEMORY STORE W/O READING
  MT   MEMORY TEST
  RC   REGISTER CHANGE
  RD   RETURN TO DOS
  RE   REGISTER EXAMINE
  SS   SINGLE-STEP
  ST   START SINGLE-STEPPING
  WA   WINCHESTER WX1 DRIVE A
  WB   WINCHESTER WX1 DRIVE B
  WH   WINCHESTER HDO CONTROLLER

Serial support: 68681

Pro: Peter Stark
Pro: Source code

Con: Some work required to play well with Quelo but it's not much.

Tutor and Tutornew

Tutor is the monitor for the MEX68KECB. Tutornew is a port to a University of Alberta SBC.

Commands
  BF     Block Memory Fill
  BM     Block Move
  BR     Breakpoint
  BS     Block of Memory Search
  BT     Block of Mernory Test
  DC     Data Conversion
  DF     Display Formatted Registers
  DU     Dump Memory (in S-Record Format)
  GD     Go Direct Execute Program
  GO     Execute Program
  HE     Help
  LO     Load (in S-Record Format)
  MD     Memory Display
  MM     Memory Modify
  MS     Memory Set
  NOBR   Remove Breakpoint
  NOPA   Reset Printer Attach
  PA     Printer Attach
  PF     Port Format
  TM     Transparent Mode
  TR     Trace
  TT     Trace to Temporary Breakpoint
  VE     Verify (in S-Record Format)

Serial support: 6850 (Tutor), 68681 (Tutornew). Note that the 68681 is not the same as the 68661.

Pro: Source code
Pro: Plays well with the Quelo assembler
Pro: Well documented

FBUG68K

Commands
  as         Assembler/Disassembler
  bf         Block of Memory Fill
  bm         Block of Memory Move
  br         Breakpoint
  bs         Block of Memory Search
  ct         Confidence Test
  dc         Data Conversion
  go         Go
  ?/he/help  Help
  lo         Load S-Records
  md         Memory Display
  mm         Memory Modify
  rd         Register Display
  rm         Register Modify
  sd         Symbol Define
  tm         Transparent Mode
  tr         Trace

Serial support: 68681

Pro: Built-in Assembler / Disassembler
Pro: Well documented

Con: Some work required

Karl Lunt

Karl Lunt wrote a monitor that was published in the May 1989 issue of 68' Micro Journal.

Serial support: Left as an exercise, looks like.

Pro: Source code
Pro: Multi user

Con: Has to be typed in from pdf

Hawthorne Technology 68000 Debugger

The Hawthorne Technology 68000 Debugger runs on the TinyGiant HT68k SBC. Here's a copy of the manual.

B  Load binary file from disk
C  Compare memory
D  Display memory in Hex and ASCII
E  Examine and/or change memory (2 bytes)
F  Fill a block of memory with a value
G  Go to an address and execute program
P  Peek
L  Load program from serial port
M  Move memory
P  Poke
R  Read binary file from disk
S  System boot.
T  Test printer
W  Write binary file to disk
X  Examine long and/or change memory (4 bytes)

Serial support: 68681

Pro: WD1770 support

Con: ROM images available, no source.