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A call for testing (Harmony Cart required)


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Testing results as of March 5 at 10:42 AM CST


Success total 73

  • 3 - NTSC Heavy Sixer
  • 7 - NTSC Light Sixer
  • 1 - NTSC Sears Heavy Sixer
  • 3 - NTSC Sears Sixer
  • 16 - NTSC 4 switch Woody
  • 1 - NTSC Sears 4 switch
  • 7 - NTSC Vader
  • 2 - NTSC Jr Rainbow
  • 4 - NTSC Jr
  • 2 - NTSC Sears Video Arcade II
  • 6 - NTSC 7800
  • 1 - NTSC 7800 dumper bios
  • 4 - NTSC 7800 w/expansion port
  • 1 - NTSC 5200 adapter
  • 3 - NTSC Coleco Gemini
  • 3 - PAL Light Sixer
  • 1 - PAL 4 switch
  • 1 - PAL Vader
  • 5 - PAL Jr
  • 2 - PAL 7800
Failure total 5
  • 4 - NTSC Jr
  • 1 - PAL 7800
As you may or may not be aware, we've been getting the 2600 to doing some really cool things using Bus Stuffing on the Harmony Cart:


post-3056-0-92674000-1487952528_thumb.jpg post-3056-0-26278600-1487952532_thumb.jpg post-3056-0-17525300-1487952536_thumb.jpg post-3056-0-04878800-1487952770_thumb.jpg


However, we've had a few people whose systems didn't work correctly with Bus Stuffing, causing the display to have vertical stripes, incorrect colors, etc:

post-3056-0-21520400-1487952687_thumb.jpg post-3056-0-19788100-1487952738_thumb.jpg


So we're trying to get a handle on what the problem is, whether or not it can be fixed, and if it can't be fixed how widespread the problem is in order to determine if its worth going forward with Bus Stuffing or not.


To that end ZackAttack and I have created this test program:



Which should output a display like this:



If you have a Harmony Cart, please run the above program on as many systems as you can and report back the results. If the display looks different than the above then please post a photo as it will help us determine what's going on. When reporting include the type(s) of system, which for me would be:

  • NTSC Light Sixer - success
  • NTSC 7800 - success
Also note that dirty contacts can cause issues with Bus Stuffing. So if you do see problems, try cleaning the contacts in your Harmony Cart, as well as your 2600's cartridge port (use Q-Tips soaked in rubbing alcohol) and then test again. When I last cleaned my Harmony Cart the results where this (unused Q-Tip on right for comparison):



To clean your cartridge port try flattening the Q-Tip with a pair of pliers before soaking them in alcohol, then insert/remove the flattened end a few times in each position of the cartridge port (unused Q-Tip on bottom for comparison):

post-3056-0-67776100-1487953507_thumb.jpg post-3056-0-49725600-1487953513_thumb.jpg post-3056-0-97003600-1487953521_thumb.jpg



I'll keep the top of this post updated with a running tally.

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NTSC - 7800 w/ Expansion Port and Composite/S-Vid Mod - PASSED

NTSC - 2600 Vader w/ Composite/S-Vid Mod - PASSED


These are my 2 easy systems to test.


I also have another 7800 un modded and my childhood Light Sixer that I can test when I have more time.

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Cool topic and great tips for cleaning cart slots. I will test tonight on my fairly early 7800 (AT-84 serial number) as well as my regular 2600's (Light Sixer, Heavy Sixer, 4-Switch Woody and Vader).


Okay, I tested the systems I have out and available and all of them passed:


4-Switch Woody (NTSC, Rev 14 board): PASSED

Vader (NTSC, Rev 16 board): PASSED

7800 (NTSC, s/n AT-84xxxx, Expansion Interface): PASSED (*)


​Tomorrow I'll test my Tele-Games Heavy Sixer and Light Sixer, both NTSC.


(*) But ugh, what shitty RF this one has compared to the 2600's. Might be time to composite mod it.


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A couple of tests:


NTSC Jr. (underside of board says Rev. F):




NTSC six-switch:




Will try to run some more tests - trying to get my other sixer working, and am in the process of re-capping my two four-switchers.

Edited by Nathan Strum
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Here is the test rom running on my PAL 7800:




I will try on other consoles and report back, but those all run the bus stuffing demos without issues so I expect them to pass the test.

I'll assume your other systems (Light Sixer, Vader, 2 Juniors) will pass, so have added them as such.
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Thanks for putting this together Darrell! I went up in the attic and dug out my systems and was able to run tests on all of them (all are NTSC):


Jr. - Passed

Vader - Passed

Sears 6-switch - Passed

4 different 4-switch Woody - All passed. Interestingly, one of them Failed on the first test (bit 7 was stuck), but after a quick cleaning of the cartridge port it passed. Are these results assuming everyone has cleaned their cartidge port/harmony cart?


I also tested your demo and a demo I'm working on and all passed.


Thanks again!


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Here's my results for my PAL 6 switch woody and PAL 7800.


2600: What is weird is this is what I get with paddles plugged in. I get a different image with a joystick. Like this but the stripes are bunched up on the left and they are grey.



7800: This is actually a rolling picture. Once or twice I just got a blank screen but just might be the Harmony?


Edited by davyK
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Here's my results for my PAL 6 switch woody and PAL 7800.

That's unexpected. Bus stuffing only comes into play to draw the black behind the digits. The digits, sync, etc. are all standard.


... :ponder: ...


BUS uses a custom bankswitching scheme - the Harmony Cart originally only supported the bankswitching in use from back in the day. Check the version of you Harmony's firmware by selecting the [.] line:



then hitting fire:



I'm running v1.05 which is when support for custom bankswitching was added.



3. Support for new bankswitching (such as DPC+) without requiring future BIOS updates
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