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johnnywc

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Posts posted by johnnywc

  3. Posted

    11 hours ago, AtariLeaf said:

    I love the name change. Like Draconian, the name seems to borrow from a Tandy Coco game of the same name 

    Thanks!  Hmmm, I didn't realize there was a Galaga clone made for the Tandy CoCo  named "Galagon"!  We actually decided to name the game after Champ Games (CHAMProgramming) PC clone that I did back in 1997:  :D 

     

    http://www.champ-em.com/galagon.htm

     

    Incidentally, I was able to reference a lot of the code in CHAMP Galagon for the 2600 version which helped immensely in the quick development! :)  

     

     

    • Like 4

  4. Posted

    42 minutes ago, Dan Iacovelli said:

    lets not forget Video Game Summit Home of the Harmony Games and btw besides showing mappy as part of Harmony Game tournament we also showed the first demo of Galaga (before the name change happened) went over big.

    That's great to hear Dan!  Thanks so much for having Mappy and the demo of Galaga available to play at the VGS! :)  

    • Like 1

  6. Posted

    On 6/23/2019 at 3:50 PM, D.A.K. said:

    johhnywc:

    Oh. Duh. I can't believe I didn't realize the switches toggle autofire! 8)

    It seems a bit better but it still seems maybe a bit slow? I dunno but it just seems a tad off for some reason.

    The challenge stage is harder than the arcade, it seems more difficult due to the firing but maybe it's just that the screen isn't as tall as the arcade.

    Thanks for the feedback!  I did some testing with Autofire off (Diff A) and the repeat rate does seem a bit sluggish, so I've cut the delay in half which seems a lot better.  I am going to keep the same constant rate for Autofire mode (same as it is now) so it's not any easier (I think Autofire is too easy as is), but will see what other people think during testing.

     

    The challenge stages are maybe a bit more difficult than the arcade, but I think the update to non-autofire mode may help for those using difficulty A.  We are still tweaking the difficulty to better match the arcade, but due to the different resolution of the arcade screen vs. the 2600 it is a challenge.  Although we are definitely trying to have 2600 Galaga be as close to the arcade game, we are also hoping that the 2600 version has it's own nuances that separate it from the arcade so people can enjoy a different experience and challenge.  :)

     

    On 6/23/2019 at 3:50 PM, D.A.K. said:

    That's another thing I was wondering. I know at this stage it would be impossible to implement screen rotation, but has anyone ever done a

    2600 game with a rotated screen so that you can have a very tall aspect ratio like many older arcade games?

    It's easier to scroll vertically on the VCS, right? If there was an advantage to scrolling horizontally, I'd think making a rotated game would be cool

    and maybe able to perform some things that couldn't be done vertically but again, I'm under the assumption vertical is easier so it would actually

    be harder to make a rotated game if so as it would be scrolling horizontally. (I realize the star field really doesn't count as "scrolling" but I think you

    know what I mean. I mean for other games in the future.)

    I think the only game that forces the user to rotate their screen 90 degrees is the homebrew "Merlin's Walls".  Although I think it's a cool idea, I don't think I will be developing games with this requirement as there are a lot of people that play these games on old CRTs and asking them to rotate them 90 degrees to play one game is probably not good for the CRT (and perhaps a bit dangerous ;)  ).

     

    On 6/23/2019 at 3:50 PM, D.A.K. said:

    However... As many Galaga players know, on the arcade challenge stages, you can use the HIGH SCORE text at the top of the screen to aim.

    Your left fire should pass through the H and your right fire should pass through the S on the 1st challenge stage.

    This is described in this article HERE.

    Is there any way objects could be placed at the top so we have a way to calibrate our aim like on the arcade?

    I especially use the HIGH SCORE for aiming on the 3rd Challenge stage with the weird new aliens in it.

    I understand what you're saying; for now the only marker you have is the actual score since putting more info up in that area is not possible without introducing more flicker.  We originally were hiding the score when enemies were flying in from the top but changed it back for this very reason.  Hopefully the score on the top and the reserve ships/level indicator on the bottom are enough to help position your ships for the challenge stages.  If not, you can always use the force :lol:  

    On 6/23/2019 at 3:50 PM, D.A.K. said:

    Will you be updating the demo with fixes and new implementations of features?

     

    Thanks for listening! You're doing an amazing job, can't wait to see the final version but it's fun as Hell to test the demos too!

    I will most likely upload a new demo in the next month or so to get feedback on the changes.  FYI the final version is scheduled for release on October 19th at the Atari Age booth at the Portland Retro Gaming Expo in Portland, Oregon.  It will be available in the Atari Age store sometime after that, usually sometime in November (Al usually provides more details as the date approaches).

    On 7/14/2019 at 8:16 PM, Tangentg said:

    There seems to be a bit of a cool down time between the 2 shots as I realized the shooting speed is a bit different from what I'm used to, and I found that out by pressing fire in quick succession and finding out only 1 shot is fired. I understand this was to make holding down autofire possible in difficulty B, but just wondering if it'd be an option to do no cool down anyway for (difficulty A).

    Yes, good observation and good suggestion!  I have implemented this and it's much better now (the delay for difficulty A is now 1/2 the delay for difficulty B when using Autofire).  I will be releasing a new demo soon with this and a few other changes.   Thanks!

    • Like 3

  7. Posted

    44 minutes ago, AW127 said:

    Can you say approximately, when the full version will come out?

    The current plan is to release the full version on Saturday, October 19th at the Portland Retro Gaming Expo, available at the Atari Age booth.

     

    Al will most likely add it to the AA store a few weeks after that.  It will be available in both NTSC and PAL60.

     

     

    • Like 5
    • Thanks 1

  8. Posted

    23 hours ago, ChildOfCv said:

    Yeah that makes some sense, but now the question is, how does the Genesis controller work when your own circuit does not?  The Genesis uses one multiplexer IC, which is pretty much the same as what the OP had.  I wonder, if we set up the Genesis controller to work exactly like your circuit, but in place of your circuit, would you end up with interference?

     

    On the Genesis, pins 1,2,3,4, and 6 are as expected (mostly):  Up, down, left, right, button, so wire them the same way you would for a normal controller.

     

    5 is VCC, so equivalent to Atari 7.

     

    7 is select, so whatever you use for the select line.

     

    8 is ground (also permanently connected to the 74157's output enable)

     

    9 is button 2, so whatever pin takes that input.

    Okay, now I'm following you.  I didn't realize that there is a multiplexer IN the Genesis controller which what was confusing me. :)

    23 hours ago, ChildOfCv said:

    So, if you wired it up to the Atari in a mock switcher setup using the above pinout changes and without the multiplexer (since the joystick IS a multiplexer), does that cause interference?

     

    I did two tests:

     

    1. Straight pass thru of all 9 wires (1:1, 2:2, 3:3, etc) with a Genesis pad.  No interference seen.

    2. All pins connected but pins 5 and 7 swapped as you suggested.  The interference line was really bad (very bright white) and the controller was acting very wonky. :|  

     

    Hope that helps!  I am going to build the circuit that has no chips  (except for an inverter or decoder to select) since that seems to have no interference either; we just need to resolve the issue where one player can control the other when the buttons are held down (also, the Genesis pad doesn't work either).  

     

    I'll post my results here. 

     

    Thanks!

    John

     

  10. Posted · Edited by johnnywc
    Added info on Goro popping balloons.

    22 minutes ago, root42 said:

    Whaaaa? No... what order? I try to fetch the ones that are blinking, but not necessarily. It's hard enough to evade the cats. 

    The 5 prizes are each worth a different amount, and for each consecutive pair of prizes that you pick up, the score multiplier increases (2x, 3x ... 6x).

     

    The values for each item are:

    • Radio - 100 points
    • TV - 200 pints
    • Computer - 300 points
    • Painting - 400 points
    • Safe - 500 points

    So, if you pick up the two radios, followed by the two TV's ... and collect the 2 safes last, you will get 7000 points total:

     

    2x100 + 3x200 + 4x300 + 5x400 + 6x500

     

    Of course, it's very difficult and challenging to do this, especially in the later levels, but if you can at least save the higher point items (painting,  safe) for last you can earn a good portion of that 7000 (depending on how many consecutive pairs you collect beforehand).

     

    Quote

    And how do I get the Bonus in the balloon intermission? It always shows 00...

    You need to pop all 15 red balloons for a total of 3,000 points (200 points each), including the last 'Goro' balloon which is worth 2,000 points = 5,000 points.  Popping all 15 balloons will also give you an additional 5,000 points for 10,000 points!  NOTE: You may notice that when you pop the Goro balloon, Goro escapes and moves up the screen more and more after each challenge stage.  At some point you will not have enough time to pop all 15 balloons by yourself but if Goro moves high enough he may pop a balloon for you. ;)

     

    Hope this helps!

     

    • Like 3

  11. Posted

    12 minutes ago, root42 said:

    I have to say Mappy is currently my favorite game. Finally broke 50k on standard. Levels after 10 get exceedingly hard! The cats are so fast. Still trying to get a hang of the door slamming tactics. I think that's the way to get rid of the cats in higher levels. 

    BA177578-D202-49A3-A41A-BA49D14C66E6.jpeg

    I'm glad ou're enjoying the game!

     

    Great score, and you made it up to level 12 - awesome! :)  I've only made it up to level 9 myself lol.

     

    Yes, the slamming doors is key, especially in later levels, plus timing the jumps off the trampolines.  Your score seems pretty low for level 12 though; I usually score about 90K in 9 levels.  Are you collecting the prizes in order?  If so, that's up to 7000 points per level! ;) 

     

    Good luck!

     

    • Like 1

  12. Posted

    3 minutes ago, Shannon said:

    Is the last version made available supposed to have sound / music?  I tried it in the Stella Beta v6.01 and v6.02 and I have no sound / music.

     

    Yes, that last version made available has both sound and music.  I just tried it with 6.0.1 and I'm getting both sound and music on my side... I'm not sure what might be the issue. :|

     

  13. Posted

    1 minute ago, ChildOfCv said:

    Could you clarify the bold?  Does the Genesis controller give you the sparkles even when connected directly to the Atari?  Or at most, with only a pin rerouter for the pin 5/7 issue?

    The Genesis controller gives no interference or sparkles when hooked up directly to the Atari.  When it's hooked up to the multiplexer with or without pin 5 wired up, the interference/sparkles are the same as with a regular joystick connected.  Hope that makes sense!

  14. Posted

    I had a few minutes and tried some more tests.  First off, if I disconnect the select line the interference goes away completely, but of course only one of the joysticks work.  Second, I swapped out the inverter for the 2x4 decoder and it had similar results (same type of interference).  Thirdly, I hooked up a diode between the select line going to the Atari and that didn't seem to reduce the interference at all.

     

    Some other observations:  The white line interference on the bottom is most prevalent when pressing left, which happens to be hooked up to INPT1 since left from the atari is being used as a select line.

  15. Posted

    On 6/20/2019 at 3:17 AM, Stephen Moss said:

    From you replies to both my and ChildOfCV's suggestion for testing it looks like the switching is probably not the cause of the issue although one last test in regards to the switching would be to disconnect the everything from the 2600 joystick ports and just have the software running as it would if the circuit was attached to see if the interference goes away. 

    If the interference is still there with the hardware disconnected then it is coming from withing the 2600 and nothing to do with the circuit, maybe you damaged a device or something to do with your code.

    However, if the interference goes away with the hardware disconnected then try placing diodes between the output of the circuit and the 2600 inputs (BAT 85, Cathodes to circuit outputs, Anodes to 2600 input pins) so that when the circuit outputs go high they are isolated from the 2600's inputs due to the diodes being reverse biased thereby allowing the 2600 inputs to be pulled high by the RIOT as they would normally be with 2600 joystick as opposed to being driven high by the circuit outputs which might be doing odd things to the RIOT.

    You could also try either separately or in conjunction with the diodes above placing the same diodes on the controller select lines, Cathode to 2600 output pins and both the Anode and a pull up resistor to the controller select pin in your circuit. I would think it unlikely but if the interference is caused by too much much current being drawn from your joystick select lines this will isolate them and prevent that.

    Hmm, I probably didn't describe it well in my previous posts, but when I configure my test program so that it does not switch (the select pin is always 0 or 1 depending on the position of the left difficulty switch), the interference drops considerably, most notably the white line on the bottom of the screen goes away.  However, the sparkling periodic static does not go away; this is the same whether or not the select line is constant or alternates from 0 to 1 twice a frame.  It seems that there the situation you described where perhaps both chips are active while the inverter goes from 0 to 1 and vice versa may be true.

    On 6/20/2019 at 4:47 AM, ChildOfCv said:

    In addition, part of the continuation of this thread is due to the Genesis game pad, which has electronics very similar to what you're building.  So another question:  With the Genesis game pad hooked up (I assume that pin 5 and 7 are suitably swapped somehow?), does it still get the interference?

    My design did not have the genesis button 2 hooked up (pin 5) but did have pin 7 hooked up.  As expected, the Genesis pad behaved the same since pin 5 wasn't hooked up.  I did try a revised design that routes the 2nd genesis button (pin 5) to INPT0 and the static/interference seems to be the same.

     

    I'm pretty sure it's not the software that is causing the issue since I also tried with Nathan's updated design that didn't use any chips (it just activates ground for the active joysitck as suggested above by Stephen) and there is virtually no static at all.  The issue with that design is that (1) it seems that it does not work if you have a Genesis controller hooked up, even if pin 5 isn't wired up and (2) if you hold down both buttons, player 1 movements are mimicked for the player 2, and vice-versa.  Nathan describes more about what he's seeing in his above post.

     

    I think my next step may be to build Nathan's circuit without the octal buffers and see if I can resolve either of the two issues (Genesis controllers not working and being able to control the other player).

  16. Posted

    On 6/22/2019 at 5:21 AM, Shannon said:

    Greetings.  Looks like we are well past the beginning of the year.  Did the ROM image of the final version ever get released?  I read through all the posts since almost this time last year and could not find anything.  :)

     

    Hello there!  No, the full ROM for Mappy has not been released yet.  I need to coordinate with Al; I know he's pretty busy with the forum upgrade.  I will post to this thread when it is available. :)

    • Like 1

  17. Posted

    13 hours ago, Kosmic Stardust said:

    I got to stage 9 and it wrapped back to 1. LOL! 🕹️💢

     

    Great job!  Yup, the demo only has the first 8 levels; the full version will have 99. :D

    13 hours ago, Kosmic Stardust said:

    This game is awesome! Also novice starts with double ship? Does the arcade do this?

    Thanks!  Yes, Novice starts with double ships.  The arcade did not do this; STANDARD or ADVANCED are meant to be more like the arcade.  The NOVICE mode is more for beginners. ;)

    • Like 3
    • Thanks 1

  18. Posted

    11 hours ago, Andrew Davie said:

     

    Thanks for that, very kind.

    You're welcome - it's much deserved!  :)

    11 hours ago, Andrew Davie said:


    I also think the use of the word 'cheat' is inappropriate. I hope I haven't ever used it - don't think so!

    No - you have not and apologies if I implied that you did!  I'm probably a bit oversensitive when I read some of the comments that suggest that we're somehow tainting or negatively altering the landscape of the homebrew community with our games.  'Champ Games' development is just me spending my free time doing something I love to do and hoping to bring some games people like to play to my favorite game system so I tend to take those comments probably a bit more personal than I should. ;)

    11 hours ago, Andrew Davie said:

     

    For each programmer, there's are different 'boundaries'. Those might be stock 4K cart, or allowing extra RAM, or Bb, or adding a coprocessor. None of these are cheating, or wrong.

    Agreed.  My 'boundary' has evolved over time, but I will admit that it was quite a challenge and a lot of fun re-visiting and finishing Avalanche earlier this year (a 4K game) with a ton of help from TJ.  Again, it's all about what inspires us as developers at a particular time since this is a part-time 'for the love of it' hobby.  

    11 hours ago, Andrew Davie said:

    My boundary has been "allowing extra RAM", but I must admit I am interested in how well Boulder Dash would run given a coprocessor.  For example, there are parts of the game system that takes multiple frames to execute that could very well be done in sub-frame speed by a coprocessor. It would run much more smoothly, I think.

    That would be interesting to see!  Certainly one of the big advantages of the ARM with Galaga is that I can run all of the movement and collision code every frame so the game is very smooth and controls are tight.  Of course there are a bunch of extras that I can do also, like the overlaid text during game play, the scrolling stars, etc. that would most likely require multiple frames to execute if not for the ARM.  

     

    Good luck and I hope you decide to someday return to Atari 2600 development!   If you do decide to go down the 'dark path of the ARM' ;), I would be more than happy to teach you the ways of the force! :D  Darrell has some great tutorials as well!

     

    Thanks,

    John

     

    • Like 3

  19. Posted

    8 hours ago, D.A.K. said:

    Greetings! I just filled out a new account to make this comment! 8)

    I had an old account here years ago but I've lost the information & don't know the email used.

    Anyhow...

    Hello and welcome to Atari Age! :)

     

    8 hours ago, D.A.K. said:


    First off, congrats on the ridiculous in quality insanity which is GALAGA for the VCS! 8)

    With just a few small tweaks here & there, it will easily be the best home version of the game for any console!

    Wow! What an accomplishment!!!

    Thank you!

     

    8 hours ago, D.A.K. said:


    As an avid player of the arcade game (I even own an arcade GALAGA cocktail!) I would like to bring up a small issue.

    The firing seems a bit off.

     

    For those of us with fast fingers who rapidly tap the button, on the arcade, you can time your shots when you tap.

    If you tap quickly twice, two shots very quickly will fire.

    The 2600 version fires 2 shots at the exact same rate, as if it expects the user to hold the button down.

    I'm sure I'm not describing exactly the issue but all I can say is the firing is off, it's not as fast or responsive.

     

    The timing of the firing is crucial in the arcade game, I can't believe no one else has pointed this out.

    It would be awesome if in the final version, this could be fixed. Maybe you can have the autofire "hold the button down" style be an

    option that can be selected from the main menu? Like have FIRING: ARCADE or AUTOFIRE and if AUTOFIRE is selected, there

    should still be a way to control the rate of the firing. I think on arcade games that have the autofire hack, you can set the rate by

    basically firing your 2 shots at the rate you wish and then holding the button down. From that point on, it fires at that rate.

     

    Thanks for the feedback!  FYI the left and right difficulty switches enable and disable auto fire for player 1 and 2, respectively.  (B = auto fire on, A = auto fire off).  Can you test with auto fire off (diff = A) and let me know if that's better?  

     

    8 hours ago, D.A.K. said:


    Looking forward to having this in my library. I have multiple Atari 2600's, a Colecovision with the 2600 adapter, a Coleco Gemini,

    an original Supercharger somewhere and one of the last Cuttle Carts produced. I plan on getting back into things and getting a

    Melody cart soon. BTW Mappy is FREAKING AWESOME AS WELL!!! My God that game is beautiful!!!

    I can't believe it's the VCS!

    Thanks again - I'm glad you like Mappy too! :)

    8 hours ago, D.A.K. said:

     

    P.S. - OH YEAH!!! DOES THE BEE TRICK WORK ON THIS?!?!?! IF NOT, IT HAS TO BE INCLUDED!!! 8)

    [GALAGA BEE TRICK DESCRIBED HERE]

    No, that bug has not been implemented but we may be able to squeeze it in.  Right now we're pretty short on ROM and I'd rather use that space for more bells/whistles and game features than adding in 'bug', but I'll look into seeing how much space it will take up and see what I can do. :D

     

    Thanks so much for the feedback!

    John

     

  20. Posted

    8 hours ago, Galactico said: 
    Hello,

Query, does anyone know why Galaga does not work for me in my ataria 2600? :(, it only sticks to a sound and only colors appear on the screen like the photos I upload.) I use the 2600 with a harmony.

I tried it with Stella for iOS, it works and I loved it. My congratulations for the game.

Sorry for my Google translation :)

Greetings and thanks

    Hello there!

     

    Galaga requires v1.0.5 of the Harmony BIOS.  Can you check to make sure that is the version you're running?  I think you just select "About" from the Harmony main menu to see the version info.

     

    Hope that helps!

    Joohn

  21. Posted

    14 minutes ago, s0c7 said:

    That's true.  But there is a growing subset who doesn't.  Back in the day, if you made bB games you were told a lot of the time "bB games suck!  You should make asm games".  I have a feeling it won't be long until we start seeing "Vanilla asm/bB games suck!  You should be using DPC+", etc.  I've already had one or two comment shot my way that if I ever do a Dungeon 3, it needs to be DPC+, 64k, etc.  Not knocking anybody else or their games.  They're great.  But the scene is changing.

    Wow - this is really sad to hear.  :(   I love both Dungeon games and I hope you make a 3rd, and it should be done the way *you* want to make it, be it with bB, assembly, DPC+, BUS stuffing, or whatever makes you happy making it.  :)  If it's a good game people will appreciate it; there's always going to be one or two people that get under your skin but in my experience they are the vocal minority.  For every "you're cheating using the ARM" post I read, there are many more "thanks for making a fun game" posts to keep me inspired.  I'm sure it's the same for you with the Dungeon games! :D

     

     

     

    • Like 8

  22. Posted

    1 hour ago, Karl G said:

    I definitely think that there is plenty of room in our community for both types of games. Making original hardware games is one skillset, and making ARM-assisted games in another. There are plenty of people who appreciate both. 

    Thanks for saying this.  I can assure everyone that Champ Games is not making ARM based games to belittle or take away anything from the games that don't use the ARM and it saddens me to hear that there are developers as talented as Andrew that feel that it's not worth pursuing their own projects for fear of their work being compared or judged.  Andrew, you certainly have all my respect and it is pioneers like you, TJ, Dennis Debro, etc. that inspired me to get into 2600 games in the first place, and IMO Boulder Dash is an absolute masterpiece. :) 

     

    I have been developing games for the 2600 for 13 years, starting with a 4K conversion of Lunar Lander, moving up to 16K for Lady Bug and Conquest of Mars.  I then burnt myself out by working on 4 games simultaneously (Avalanche, Wizard of Wor, Rip Off and Moon Cresta) and stopped developing for 8 years.  When I rejoined the scene back in 2015 and was introduced to DPC+ by Darrell, that inspired me to get back into game development because for me it was *fun* again!   Making a game like Scramble was very satisfying and challenging, and for me the ARM just set the bar higher as to what my expectations were and opened up a whole new door to an opportunity to be creative.  As much as the ARM may assist development (mostly because I can write game logic in C at the cost of using more ROM typically), the true challenge is still the 6502 kernels and bridging the two vastly different architectures to make a game that is fun and within the confines of the TIA (2 sprites, 2 missiles, the ball, and the low res playfield).  I also program with the ARM because, frankly, I'm getting old and the development is much more quicker.  I personally don't have the time or patience to work on a game for years and I take my hat off to those who can stick to a project that long (my limit is about 6 months ;)).  

     

    Anyway, those are some of my thoughts, and back to what Karl G said; I think there is plenty of room for both types of games to exist.  Right now I think I'm the only one making ARM games as Darrell is on hiatus and most of the games coming out this year look amazing (my personal favorite is Aardvark).  Personally, I wish people would stop using the word 'cheat' to describe what we do as it does carry a negative connotation.  I am very transparent with everyone who asks "what's the magic" behind my games so I think we should leave it up to the players to decide whether or not they want to enjoy them for what they are.  :)

     

    Thanks,

    John

     

     

     

    • Like 15

  23. Posted

    2 hours ago, ChildOfCv said:

    Yeah.  That's called a decoupling capacitor.

    Great thx, I'll give it a shot.

    2 hours ago, ChildOfCv said:

    Well, no, I mean unplug only one line at a time from the link between the octal buffers and the plug to the Atari.

     

    For example, remove the "up" wire.  See if that improves the signal.  Especially when you press "up".

    Okay, but the test is to stop doing the switch, though I guess you did that too.  You said that it did help, but not completely?

    Yeah, that sounds right

    Okay, that makes more sense.  I can run this test too.

    5 minutes ago, ChildOfCv said:

    Also, one other test:  Run one joystick through one buffer directly to the Atari and skip the selector entirely, and see if the interference continues

    Will do!

     

    Thanks for the help, it's much appreciated!

    John

     

  24. Posted

    7 hours ago, Stephen Moss said:

    Interesting...

    1) Is the interference there if you permanently(no switching) software select one joystick or the other? If no go to step 4.

    I modified my test software so the Color/BW switch enables/disables switching.  When disabled, the left difficulty selects which joystick to test (joystick 1 or 2) by making the select line a constant 0 or 1.  The interference does reduce when I disable switching and is the same regardless of which joystick is active.  By reduced interference; with switching enabled, you see a constant sparkling white horizontal line at the bottom of the screen, about 3 inches long that gets more intense when you activate any switches on either joystick.  When switching disabled, this line disappears.  However, there are occasional 'dot's of interference, almost like static, that appear all over the screen, again only when you're moving the joysticks.   This 'static' doesn't seem to improve whether switching is enabled or not.

    7 hours ago, Stephen Moss said:

    2) Is the interference there if you manually select one joystick or the other (tie selection lines directly high/low - driven from 2600 output)? If no go to step 4.

    I'm not sure what you mean here, but I did wire the OE line directly to VCC and then GND to remove the select line connection to the Atari.  With this the visual output seemed the same as using a constant select line as in step 1 (no switching).  I alternated VCC and GND so it would activate one or the other joysticks to see if there was a difference.

    7 hours ago, Stephen Moss said:

    3) Check the wiring for the Joystick that cause the interference & if that looks OK try swapping the ICs with those from the non interfering Joysticks in case you have a dud one.

    This seems to be N/A since both joysticks/octal buffers seem to be exhibiting the same behavior.

    7 hours ago, Stephen Moss said:

    4) If you are using a single control signal and inverter it is possible the propagation delay of the inverter results in a brief period when the outputs of both Joysticks are active at the same time in which case either diode isolation or using two selection signals to switch one off then the other on should allow enough time for the out of one to fully turn on before the other is turned on.

    If you have two control line to use try that method first, the instruction cycle time should be slow enough that the instructions used to turn one off and the other on can immediately follow each other, additionally if that does solve the problem it could suggest that the ROIT inputs do not like being fed a voltage for some reason.

    I did modify Nathan's original design so I do have 2 select signals (the intent was to use them to select 1 - 4 joysticks) so I can test with two select lines.  I think what you're saying is to connect one select line each to one of the octal buffers?  Then in software I would first disable one buffer with a write to SWCHA and then enable the other buffer with another write to SWCHA?  (I would then disable/enable the other in reverse order when selecting the second joystick).

     

    During VBLANK

    - read joystick 1 values

    - disable select line for joystick 1

    - enable select line for joystick 2

     

    During OVERSCAN

    - read joystick 2 values

    - disable select line for joystick 2

    - enable select line for joystick 1

     

    Of course it looks like the OE is triggered low so by enable I would write a 0 and by disable I would write a 1.  Does that sound right?

    7 hours ago, Stephen Moss said:

    I am not sure why directly driving the ROIT inputs would be a problem but if it is then diode isolation to ensure they are only pulled down should correct it.      

    Hmmm can you elaborate what you mean by diode isolation for us newbies? ;)  I know diodes are used to ensure current flows only in one direction, but I'm not exactly sure what type to use and what pins I should be using them on.  The joystick inputs?  The select lines?  

     

    Thanks so much for the help!

    John

  25. Posted

    9 hours ago, ChildOfCv said:

    Some troubleshooting steps, if you go that way:

     

    1) Try a 0.1uF ceramic capacitor between VCC and GND on the 74xx chips

    I think I have some capacitors that came with my start up kit lol, I'll see what types they are and give this a try.  By 'between VCC and ground', do you mean wire VCC to one end of the capacitor and ground to the other?  

    9 hours ago, ChildOfCv said:

    2) Try disconnecting one joystick to Atari line at a time to see if things improve

    Do you mean actually unplug the joystick from the multi-tap port?  If so, I did try this and that didn't seem to improve.

    9 hours ago, ChildOfCv said:

    3) Assuming you're running your game.  See if reading only one stick or the other helps

    I actually put together a test app, but it's doing the same during the game. 

     

    During VBLANK it reads the ports and stores the values in joystick 1 variable. 

    Once completed, it then toggles the select bit so the other joystick becomes active (joystick 2).

    The screen is then drawn.

    During overscan, it then reads joystick 2 and stores the values in joystick 2 variable.

    Once completed, it then toggles the select bit again so the other joystick becomes active (joystick 1).

     

    9 hours ago, ChildOfCv said:

    4) Wire up a 555 timer at around 60Hz and attach its output to various Atari inputs to see if that brings out the interference

    Hmm I don't think I have a 555 timer so I'll have to look into getting one of those to perform this test.

    9 hours ago, ChildOfCv said:

    One thing I wonder about, is if there needs to be tiny delay between deactivating one bus transceiver and activating another.  If one goes active while the other is still in the process of giving up, that could cause a large power draw as one is trying to pull a control low while the other attempts to keep it high.

    See below; I did run some additional tests suggested by Stephen.

     

    Thanks!

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