johnnywc

That would be great, any help is greatly appreciated!

Gotcha, thx for the clarification! I was panicked that we didn't have a solution that had at least the interference cleared up. I agree, I don't think the interference is related to the connector (or at least one specific connector).

Hi Nathan, thx for the clarification. Hmm, I thought the 4 player adapter you put together used the grounding logic and not the chips and you weren't seeing interference with it (just control issues)? Do you mean the first iteration of the adapter that used the multiplexers? Maybe I'm confusing the two?

Okay, I had a few minutes to run some tests: On the unmodded RF 4-switch Atari: 1. If switching is disabled, the interference is greatly reduced to only a few sparkles when you move either joystick. The interference is the same whether or not DUMP_PORTS is enabled or disabled. 2. The distance of the circuit to the Atari does not seem to have any noticeable effect on the interference (when switching is enabled). I had it right on the Atari vs. 6 feet away. On the AV-modded 7800, the circuit works perfectly and there is absolutely zero interference (the picture is crystal clear) and there is no interference when either or both of the joysticks are moved in multiple or different directions. This is consistent with what we saw in Nathan's original design that used multi-plexers; no interference on AV-modded Ataris. The interference is only on unmodded Atari's using RF. I'm not exactly sure how to measure the ohms at the TV connector for the RF Atari. I have a potentiometer that I can measure ohms with but I'm not sure what I'm measuring across. Do I disconnect the cable from the TV? Apologies for the simple question!

Will do! I know Nathan is seeing the same interference on his machine also so I don't think it's just my output connector but I'll check. A few feet, I will test by moving the board (I have it connected to a 12 ft cable) and see if that makes a difference. Thanks for the suggestions!

Okay, that makes sense. Yes Player 2 gets 192 scanlines of select since I set DUMP_PORTS right after vertical blank is done and then switch to player 1 when I turn on VBLANK at the beginning of overscan, so that gets 70 scanlines. Doing some quick math, Player 2 is 192/262*5.0V = 3.66 V and Player 1 should be 70/262*5.0 = 1.33, which is almost exactly what I'm measuring. Good idea, I'll update my test program and see if it makes a difference. I already have the ability to turn off switching using the left difficulty switch and then I can use the right difficulty switch to have DUMP_PORTS be a constant 1 or 0. As I mentioned above, I'm activating the DUMP_PORTS right after vblank is over and turning it off at the beginning of overscan. I can switch this logic so I'm dumping the ports at the beginning of overscan and resetting it back to 0 at the end of vertical blank and see if that makes any difference. Unfortunately I only have a modified 7800 so I can't test if the interference is there, but I will test to see if there is interference on the modded 7800. I have a modded 2600, modded 7800 and an unmodded 2600 which is what I'm doing most of my testing with. Thanks for the ideas, I'll post my results soon. John

Okay, I had a few minutes today and hooked up diodes (1N148) between the bus transceiver outputs and the Atari, with the cathode nearest to the transceivers. Since we're connecting the outputs of the 2 transceivers before connecting to the Atari, I assume one set of diodes is sufficient *after* the outputs are connected? The good news is that the interference is reduced a lot, but there is still a good amount on the screen. Whats odd is that the interference is a white static line on the top of the screen and short lines on the bottom of the screen which is different than what we saw before using one of the direction pins (we used LEFT) as the select line where the static mostly appeared on the bottom and wasn't as pronounced. I'm not sure if this was pointed out explicitly, but the interference is only visible with non-modded Ataris using an RF connector (there is no interference if you are using AV input with a modded Atari). Also you mention above about the Genesis controller; all my tests are using stock Atari joysticks. I'm hoping that maybe using a 74LS04 inverter will reduce the RF interference (if that is indeed what it is) based on that blurb above that I found on the net that suggested the LS vs the HC would be better for RF. Another small point, and this may be a non-issue but figured I'd post my observations: When I do a straight-thru test (that is, just hook up the joystick directly through the Atari), as expected an open connector measures at 5V and when closed it goes down to 0V. This is also true if I pass the joystick input through a bus transceiver (x245). However, when I add in the inverter with the pull up resistor and have it switching between 2 bus transceivers, when I measure the output at the Atari for a direction it measures about 5V for open (4.98) but only drops to 3.68V when a switch on 1 joystick is closed. I assume this is because the value is rapidly changing from 0V for the closed switch on Joystick 1 and 5V for the matching open switch on Joystick 2? EDIT: I just did a test with the button, measuring the voltage at the Atari pin 6. If both buttons are open (not pressed), it's about 5V (4.98). If both buttons are pressed, it's 0.56V (almost 0). However, if the button on the joystick that is triggered on pin 9 (select line) when it's low is pressed, the voltage is read at 1.67 volts. On the joystick button that is triggered on pin 9 being high, the voltage is 3.86V (but still registers as a low). Again, I assume these voltage measurements would be better viewed on an oscilloscope since the measurement at that pin is being changed 120 times a second (twice per frame) as we set and reset DUMP_PORTS on VBLANK. Regarding the interference, it does get much worse when a switch is active (ie. you press the button or move in a direction) and more prevalent when you combine them. Also, the interference is greater when switches on the joystick that is triggered on low pin 9 (DUMP_PORTS = 0) are active vs. the other joystick. Based on these findings, should we expect different results with the open collector bus transceivers? I'm going to try with the octal buffers (x244) and see how the interference compares. Any other suggestions are welcome! I'll also pick up some 74HC05's as you suggested above. Thanks again for all the help! John

Great thanks. The LS are slightly more expensive but I found this blurb on the 'net re: RF interference. I'm not sure how accurate it is but for a couple bucks I'll pick up a few LS04's and see if it makes a difference also. " For the gates over-all: HC is very ESD sensitive - in circuit and out of circuit, it will 'latch up' in circuit and fry. LS is a power hog but it's hardy. HC designs usually have 'richer' frequency content - so if RF emissions are a problem go with LS if you can. " Okay, I ordered a couple that were in stock and they'll be here by Wednesday. RE: the inverting multiplexer; can you recommend a specific chip? What does a 74xx05 do? As for my progress, I did re-wire up the xx245 bus transceivers (no diodes yet) using an 74HC04 and using pin 9 as a select through a 10K pull up resistor and the control works great, but as expected there is interference. I did notice that the interference goes away almost completely when I disconnect vcc to the inverter (not sure if that info is helpful). Thanks again for all the help! John

Okay, I'm a little embarrassed but I got it working with the 10K resistor; I was not hooking up the pull up resistor correctly and wasn't taking the measurement after the pull up resistor. 😳 Probably explains why I got a C+ in EE209 I'm going to re-build the rest of the circuit using the octal buffers (244) or bus transceivers (245) and confirm that the joystick switching still works (like it did before) and then move on to trying to reduce the interference using your suggestions with the diodes to simulate open collector variant. At this point I may just take the plunge and invest the 10 bucks in 2 of the 74ALS641. Before I place an order, do you see any benefit in getting 74LS04 inverters vs the 74HC04 inverters that I'm using now? I'm not sure what the difference is but since the shipping from Mouser is per order and is usually as much as the components I'd like to try to order everything I need at the same time. One change I'm going to suggest is to use pin 9 as the select line as it looks like the harmony cart checks to see if pin 5 is high (INPT0) on startup to determine if paddles are connected (as many games do). If we use pin 9, then INPT1 will be logical high on startup and we can ground INPT0 so it's low and we can use this as autodetection for the multi-tap (INPT0 = 0 , INPT1 = 1 on startup) which differs from paddles/Genesis controller which has both INPT0 and INPT1 high on startup or a regular joystick which has both INPT0 and INPT1 low on startup. Using pin 9 will make the QuadTari/multi-tap "Harmony friendly" This it the API I need to have nailed down in the next week or so (how to detect a multi-tap is connected and how the switching is going to take place) since that is in code and hopefully we can resolve the interference issues without changing the API. I'll post my results here as I make progress. Thanks again for the help and the education on pull up resistors! EDIT: Checking Mouser.com, there are a couple options for the 74ALS641: https://www.mouser.com/ProductDetail/Texas-Instruments/SN74ALS641AN?qs=sGAEpiMZZMs9F6aVvY09bjMKmt1NCXfKtUc9D2Iyav8%3D vs. https://www.mouser.com/ProductDetail/Texas-Instruments/SN74ALS641A-1N?qs=sGAEpiMZZMs9F6aVvY09bknyBMcqVx4yQ%2F%2B7v5EBHck%3D Looks like the difference is in Low Level Output Current (24 mA vs 48mA) and min/max supply voltage (4.5V - 5.5V vs. 4.75V - 5.25V). Also the second one has a lead time of 8 weeks and the first one is in stock. Would the first one be suitable with the 24mA/4.5V - 5.5V?

I'm pretty sure that I'm not clearing VBLANK anywhere else (I stepped through the debugger). I can try that. I know for a fact it worked before so something is amiss. However, when I first tested it I had it going through my 4.7K resistor network that I am using for the joystick inputs and it did work. I abandoned that when it stopped working which I now know is because I fried the inverter lol, so I'll try that again and see how it goes with the 4.7K and I'll also try a 100K. Silly question, but wouldn't a 100K be stronger than a 10K or am I misunderstanding how resistors are measured? I know they're in Ohms and Voltage = Current * Resistance (V = IR); probably the only thing I remember from EE 201/209 lab back at the University of Connecticut in 1988 I'll also try another Atari in case I damaged my test one, but the paddles do work great on the system so I don't think I damaged it at all. Any other suggestions are welcome and thanks again! John

Thanks for the explanation! I'm able to get the signal high by connecting pin 5 to a 10K pull up resistor and the other end of the pull up resistor to +5V. Unfortunately no matter what I set VBLANK to, the value at the end of the resistor connected to pin 5 is always 5V. For a test I connected the other side of the resistor to ground and as expected the value on the vcc side was 5V and the other side was 0V. Setting bit 7 of VBLANK doesn't seem to be having any effect on what pin 5 (or 9) are doing. Of course it's quite possible that I'm just doing something incorrectly or have it hooked up wrong. Right now I'm just working with the input from the Atari, (vcc/ground/pin 5) and the 10K resistor and measuring voltage at the pins. Once I can prove that I can switch the logic of pin 5 using VBLANK, I'll add in the inverter and then the bus transceivers one at a time, measuring along the way to make sure I don't mess anything up. Interestingly it seems that I damaged my inverter chip (74HC04) at some point (probably screwing around with disconnecting/connecting wires to view the static) as I did an independent voltage test on the input/output pins and no matter what, all of them were high (5V). I switched out another chip and it worked as expected (1->0, 0->1), so that explains why I did see it working for a bit when I first connected the circuit and then why it seemed to just stop working. I'm not sure where to go from here, this may be over my head but I'm very interested in learning if you have any other suggestions or helpful tips. I'm releasing Wizard of Wor Arcade and Galagon at the PRGE on 10/19 and both games are supposed to support this interface. Although it's very unlikely that the adapter will be ready to sell by then, I want to at least nail down the API. Being able to use pin 5/9 vs. one of the direction pins (we were initially using LEFT pin 4) would be ideal so hopefully we can get a prototype working with the switching at least. Thanks so much! John

So I'm having some difficulties using the VBLANK method to select a joystick. It was working for a bit yesterday but after I disconnected the circuit and reconnected it, it's no longer switching. I modified my test program so you can use the difficulty switches to enable/disable the switching, and when the switching is disabled I use one of the difficulty switches to enable or disable the VBLANK dump ports bit (0x80 of VBLANK) so it's constant. It seems even if VBLANK bit 0x80 is set high constantly, the voltage coming off of pin 5 and 9 is always 0 (which explains why it's not switching). Maybe I'm misunderstanding how we can use pin 5 (or 9) as a select line? I would assume you would set VBLANK to 0x80 and that would drive pin 5 and 9 high (on both ports), and if I set VBLANK to 0 it would drive pin 5 and 9 low, so I wrote my 'switching' code to read joystick 1 (assumes pin 5 is low), enable DUMP_PORTS (VBLANK=0x80, sets pin 5 high, or so I thought), wait a bit, read joystick 2 (assumes pin 5 is high), and then disable DUMP_PORTS (VBLANK=0, sets pin 5 low I thought). The odd thing is that this *was* working when I first hooked it up so I'm not sure if I fried something on the Atari? Right now I'm just taking measurements directly off port A of the Atari (no joysticks) and pin 5 is always low no matter what I'm setting VBLANK to. I confirmed that the other pins (U,D,L,R and the button) are all high and go low when I enable them with a joystick (directly connected to the Atari) so I'm pretty sure I'm measuring it right (I'm measuring voltage with a multimeter). For what it's worth, I did hook up some paddles with Video Olympics and it works fine so whatever is charging the capacitors in the paddles still works fine. Any help is appreciated! Thanks, John

Well, some good news: using 4.7K pull-up resistors and switching using pin 5 by enabling/setting DUMP_PORTS (0x80 on VBLANK) works great! As it turns out, I must have last used tri-state bus transceivers (74HC245N) since those were in my bread board, so I used those in my test. The interference line is pretty pronounced; worse than with using the left pin as the select line. I'm going to try with the octal buffers (74HC244N) and see what it looks like with that. I think the reason why Nathan went with the solution above is because there is no interference just using ground to select the active joystick, but that solution has it's own issues with control and not registering diagonals. Do you think using the 74ls157's instead would eliminate the interference? I should note that I'm using a 74HC04 inverter; I'm not sure how that compares to the 74ls04 inverter in your design above (what does the HC and LS stand for?). One thing that I did notice that as I was fiddling with the wires while it was connected, when I disconnected the wire going into the inverter input the static was really bad all over the screen, and would go away completely (even the line on the bottom) when I moved the end of the wire (still disconnected) away from the breadboard. Not sure what it all means but figured I'd mention it. I'll take a video and post it on YT so you can see what I mean. EDIT: Very strange, but I just rehooked up the circuit to the Atari to get some video of the interference and the VBLANK switch isn't working (it's always registering joystick 1). It was definitely working before so I'm not sure what changed. Anyway, at a minimum you've improved our design; using the VBLANK register certainly has it's benefits, including simpler code and allowing a joystick plugged into the adapter to be used with any joystick-enabled game.

Hello there! Thanks so much for this; I think it's very similar to the one above that uses the octal buffer? One issue is that the select line is on port 2; the ultimate goal is to multiplex two joysticks on 1 port so the other port is free for the Atarivox, but I see you have a solution for that below. My concern is that we'll still have the interference with this design since it is similar to the one above that uses the octal buffer (I did the design with 2 SN74HC244N chips). The control was great but the interference was bad. Is there less of a power draw from the 74ALS641? Also it looks like those chips are very expensive if I'm reading it right; about $4 each, almost 10 times more than the 74HC244N! 😮What is the advantage between using a bus transceiver vs. an octal buffer? Wow that's a very good idea about using the TIA blank register and dumping the pots using the VBLANK register! One benefit I would think would be that you could use a joystick plugged into the adapter for games that aren't doing the switching since that bit would always be low (assuming the game is not dumping the ports) so it would always read from one joystick. Regarding the 20K resistor network; I had bought a bunch of 4.7K RNs for the octal buffer design; do you think that would be suitable for this design as well? Thanks again! I'll need to order a couple of the bus transceivers to test this; in the meantime I'm going to test my octal buffer solution using the VBLANK dump pots as the select line. I assume I should be able to do the following: During vertical blank: - read joystick 1 - dump pots (VBLANK bit 8 = 0x80, SEL = 1) During overscan: - read joystick 2 - disable dump pots (VBLANK bit 8 = 0, SEL = 0) In this way both joysticks can be read every frame and there is a sizable amount of time between VBLANK dump pots being set/reset.

Thanks for the quick feedback! I'll mention this to Nathan @gauauu so he can measure the voltage; unfortunately I don't have the circuit built over here. Looking at the schematic, do you see anything obvious that may be causing the issue? It seems that the directions work fine if done individually (up, down, left, right) but only cause issues when they're diagonal. I'm not sure what the difference would be if 1 or 2 are activate at the same time. Speaking from someone who has very little experience with this; the circuit I built with the octal buffers had pull up resisters on the joystick inputs. Would those be needed too plus the diodes that were added to ensure the current flow was going to the right way (we previously had the issue where one joystick could control both players sometimes).

Hello all, I know it's been a while (busy summer!) but Nathan T. and I are back at trying to get this multi-joystick circuit working. Right now we are using the design where the joysticks are connected in parallel and activated by hooking the select line to ground through a diode. Although this did work by removing the interference, there was a control issue where one player was able to move the other player when both where pressing in the same direction or action (holding down the button for example). It was recommended above to put diodes on all of the inputs from the joystick (which Nathan @gauauu) has done in the latest design. The good news is that the control issues seem to be fixed, but there is an issue with diagonal movements. They don't always register for some directions and for others (when you're pressing RIGHT for example), the diagonals never register. Here is a schematic of what Nathan is testing with; any ideas would be greatly appreciated! Seems like we're getting close!

Hi Richard, I don't believe any CDF/DPC+ games run on the UNO cart (Draconian, Mappy, Scramble, Galaga, etc.) but I believe someone in the UNO cart community may be working on that.

Hello all, With the release of Wizard of Wor Arcade approaching (October 19th @ the Portland Retro Gaming Expo), here is an updated demo ROM that is 99% complete. Note that this new demo requires Stella v6.0.1 or better (or Stellarator) to run in an emulator, or it can be run from the Harmony or Harmony Encore. The demo ROM contains all the features of the full version with the following exceptions: The word "DEMO" is alternately displayed with the SKILL level on the title page. Savekey support for high scores and game options has been disabled (AtariVox speech is supported in the demo). The Maze Editor and ability to play with custom mazes is disabled. The game will go back to DUNGEON 1 after DUNGEON 8 is completed. The full version contains 99 levels Directions for playing the game can be found in this post, with these additional notes: On NOVICE skill, the first 3 dungeons are always the same set of 3 mazes. On ADVANCED skill, starting on the 2nd dungeon, the walls of the maze may crumble during a level, making it more difficult to hide from the monsters, so finish the dungeon as quickly as possible! The right joystick button can be used to change the # of players on the title screen (same as the SELECT switch) Note that 2 player co-op mode is not available if there is a Savekey or Atarivox plugged in (since 2 joysticks are required). Wizard of Wor Arcade supports Nathan Tolbert's QuadTari adapter that allows you to connect 2 joysticks up to the left joystick port, freeing up the right controller port for the Savekey/Atarivox. This will be made available sometime after the release of the game (Nathan will be providing details). To do: Mike Haas (aka iesposta) has completed more Atarivox speech phrases that need to be added A sound effect for the crumbling walls in ADVANCED mode will be added Game play tweaks/difficulty ramping if needed Thanks again to Nathan Strum for the graphics, Mike Haas for the Atarivox speech and sound fx, Ross Keenum for additional sound fx (Wizard shot, Worluk shot and Wizard escape sounds), and to all those who have provided feedback with testing, most notably James & his crew over @ ZeroPage Homebrew! I also want to thank Nathan Tolbert for his many hours spent refining and testing the QuadTari interface and accommodating my specific requests needed to make it work with one controller port to free up the second one for the Atarivox/Savekey. The box, manual and label have been finished by Dave Dries (thanks so much Dave!) and he's done an amazing job! Al will be posting teaser shots soon! Any feedback is appreciated! Thanks, John wowarc_20190812_demo_NTSC.bin wowarc_20190812_demo_PAL60.bin

It will be good to see you too Steve!

Hey Jesse, I know @Albert has been working with Richard H. and I'm pretty sure they were able to come up with a new design that fixes the issue. I'm not sure about availability at PRGE; I know Al is flat out getting a whole slew of games ready for release at the show. 😮 PS It will be good to see you at PRGE!

Hello there! We have released two ROMs; the initial one last year and the updated one in February for the maze editor contest. I do plan on releasing an updated ROM demo in the next week or so. I believe Al is currently working on a Downloads section where people will be able to pay/contribute for full ROMs; I'm not sure about copies of the manual though. I'm sure he'll be releasing more info on this in the near future. Thanks! John

Awesome! It will be good to see you again Bob! Now we just need to get @Nathan Strum to go for a full-fledged Lady Bug development team reunion!

Both players start on the screen in NOVICE skill level and in CHALLENGE MODE.

Thank you so much for your review of Mappy, I'm so glad that you are enjoying playing the game as much as we had making it!