https://github.com/cavnex/mc6809/blob/master/documentation/patch.md

   The Williams Stargate subroutine at $119 contains a minor error. At
   $11D if the value of the U register is nonzero, the BNE instruction
   jumps incorrectly into the middle of the next instruction.

   [60]Williams Stargate disassembly and hex dump

   The intent is to skip over the JSR $115. Instead the code jumps to
   $120, executing $01 $15. $01 is documented as an invalid opcode,
   however the Motorola 6809 actually executes it as NEG <$15. In
   contrast, the Hitachi 6309 traps on the illegal instruction.

   The code at $11D can be patched to execute BNE $0122 instead of BNE
   $0120 as follows.

   Assuming the first Stargate ROM is a file named "01" with SHA-1 hash
   f003a5a9319c4eb8991fa2aae3f10c72d6b8e81a use the following command
   line:

          echo "11e: 03" | xxd -r - 01

   Alternately change $2601 to $2603 using a hex editor.

   End result is a file with SHA-1 hash
   6a467d3619dae915d192c3b5171064a5c273c870 which is now Hitachi 6309
   compatible.

References

   Visible links
   1. https://github.com/opensearch.xml
   2. https://github.com/cavnex/mc6809/commits/master.atom
   3. https://github.com/cavnex/mc6809/blob/master/documentation/patch.md#start-of-content
   4. https://github.com/cavnex
   5. https://github.com/cavnex/mc6809
   6. https://github.com/join?source=header-repo
   7. https://github.com/features
   8. https://github.com/features/code-review/
   9. https://github.com/features/project-management/
  10. https://github.com/features/integrations
  11. https://github.com/features/actions
  12. https://github.com/features/packages
  13. https://github.com/features/security
  14. https://github.com/features#team-management
  15. https://github.com/features#hosting
  16. https://github.com/customer-stories
  17. https://github.com/security
  18. https://github.com/enterprise
  19. https://github.com/explore
  20. https://github.com/topics
  21. https://github.com/collections
  22. https://github.com/trending
  23. https://lab.github.com/
  24. https://opensource.guide/
  25. https://github.com/events
  26. https://github.community/
  27. https://education.github.com/
  28. https://github.com/marketplace
  29. https://github.com/pricing
  30. https://github.com/pricing#feature-comparison
  31. https://enterprise.github.com/contact
  32. https://github.com/nonprofit
  33. https://education.github.com/
  34. https://github.com/login?return_to=/cavnex/mc6809/blob/master/documentation/patch.md
  35. https://github.com/join?source=header-repo&source_repo=cavnex/mc6809
  36. https://github.com/cavnex
  37. https://github.com/cavnex/mc6809
  38. https://github.com/login?return_to=/cavnex/mc6809
  39. https://github.com/cavnex/mc6809/watchers
  40. https://github.com/login?return_to=/cavnex/mc6809
  41. https://github.com/cavnex/mc6809/stargazers
  42. https://github.com/login?return_to=/cavnex/mc6809
  43. https://github.com/cavnex/mc6809/network/members
  44. https://github.com/cavnex/mc6809
  45. https://github.com/cavnex/mc6809/issues
  46. https://github.com/cavnex/mc6809/pulls
  47. https://github.com/cavnex/mc6809/projects
  48. https://github.com/cavnex/mc6809/actions
  49. https://github.com/cavnex/mc6809/security
  50. https://github.com/cavnex/mc6809/pulse
  51. https://github.com/cavnex/mc6809/blob/d3112c365c944ae70b2c94c00380b480c4a76b58/documentation/patch.md
  52. https://github.com/join?source=prompt-blob-show&source_repo=cavnex/mc6809
  53. https://github.com/cavnex/mc6809/find/master
  54. https://github.com/cavnex/mc6809
  55. https://github.com/cavnex/mc6809/tree/master/documentation
  56. https://github.com/cavnex/mc6809/find/master
  57. https://github.com/cavnex/mc6809/raw/master/documentation/patch.md
  58. https://github.com/cavnex/mc6809/blame/master/documentation/patch.md
  59. https://github.com/cavnex/mc6809/commits/master/documentation/patch.md
  60. https://github.com/cavnex/mc6809/blob/master/documentation/stargate-patch.png
  61. https://github.com/site/terms
  62. https://github.com/site/privacy
  63. https://github.com/security
  64. https://githubstatus.com/
  65. https://help.github.com/
  66. https://github.com/contact
  67. https://github.com/pricing
  68. https://developer.github.com/
  69. https://training.github.com/
  70. https://github.blog/
  71. https://github.com/about
  72. https://github.com/cavnex/mc6809/blob/master/documentation/patch.md
  73. https://github.com/cavnex/mc6809/blob/master/documentation/patch.md

   Hidden links:
  75. https://github.com/
  76. https://github.com/cavnex/mc6809/blob/master/documentation/patch.md
  77. https://github.com/cavnex/mc6809/blob/master/documentation/patch.md
  78. https://github.com/cavnex/mc6809/blob/master/documentation/patch.md
  79. https://github.com/cavnex/mc6809
  80. https://github.com/cavnex/mc6809/issues
  81. https://github.com/cavnex/mc6809/pulls
  82. https://github.com/cavnex/mc6809/actions
  83. https://github.com/cavnex/mc6809/projects
  84. https://github.com/cavnex/mc6809/security
  85. https://github.com/cavnex/mc6809/pulse
  86. https://desktop.github.com/
  87. https://github.com/