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CoCo3 RF and joystick question

voidstar78

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Greetings, a couple CoCo questions:

1) I have a CoCo1 with the little $2 RF adapter, with a coax-looking cable that goes from the adapter into an LCD TV that I found with a coax-style RF input. It works fine, I get nice audio and video from the CoCo1. I tried this same cable with the CoCo3, but it's not working. I tried CH3/4, no go. I plugged back into CoCo1, cable works fine there. The RCA style (red/white) cables work on the CoCo3 and same old LCD TV. Reading thru the CoCo3 manual it seems this same RF cable ought to work. Any thoughts? (I was hoping the CoCo3 could mirror outputs to both the RF and RCA outputs at the same time)

2) I ordered an Atari to 5-pin DIN joystick adapter, but none of my Atari joysticks are working on the CoCo. Specifically I was trying to get Shanghai to work. It will only move along the 8-way direction, not a smooth movement of the "pointer" across the screen. Can anyone recommend any Atari with adjustable sensitivity? (or if anyone has a spare Deluxe Tandy joystick to sell, PM me)



Thanks!
 

Eudimorphodon

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2) I ordered an Atari to 5-pin DIN joystick adapter, but none of my Atari joysticks are working on the CoCo. Specifically I was trying to get Shanghai to work. It will only move along the 8-way direction, not a smooth movement of the "pointer" across the screen. Can anyone recommend any Atari with adjustable sensitivity? (or if anyone has a spare Deluxe Tandy joystick to sell, PM me)

I suspect this would be expected behavior with most Atari joystick adapters. Atari joysticks are just digital switches; four buttons for the cardinal directions and you can record a diagonal when two buttons are held down together. The CoCo's native joysticks are analog; there's a variable resistor for horizontal and another for vertical and a set of analog/digital inputs in the computer can resolve 64(i think?) steps in both axis. So effectively if you hold the joystick in one corner the input will be (0,0), the opposite corner will be (63,63), and if the stick is perfectly centered it's going to be something like (31,31). (You can extrapolate the rest.) Most adapters to use digital joysticks on analog computers just define nine different grid points for each possible reading of the joystick and return that when the joystick is moved, so it's as if the joystick has been slammed hard (instantly) in one of 8 directions (or centered) for every movement. This works fine on a lot of games, but if the program you're using depends on "absolute positioning" (IE, a point on the screen directly coordinates with a possible joystick position) then it's obviously not going to be ideal.

If you're willing to do some cutting and soldering most IBM PC analog joysticks can be adapted to work on a Tandy, but you do need to take the joystick apart, a plug adapter alone won't do it. (The A/D converters in the CoCo work on a slightly different principle than the ones on a PC joystick port, so the wiring on the variable resistors needs to be changed.)

Re: the first question, if you're plugged into the RF port on the CoCo 3 that cabling should work the same as it does on the CoCo1, if it doesn't it could be the RF modulator in your CoCo3 is toast.
 

voidstar78

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Re: the first question, if you're plugged into the RF port on the CoCo 3 that cabling should work the same as it does on the CoCo1, if it doesn't it could be the RF modulator in your CoCo3 is toast.
I was afraid that might be the case. Shame since it is otherwise a very pristine CoCo3. Would something like a brown out or power spike (at some time in the devices history) toast an RF modulator? My CoCo1 is nearly 10 years older, glad its output is still working fine. Since the RCA outputs still work fine (and look crisp), I won't attempt to open the unit and replace the modulator -- not worth the risk of breaking or scratching something else. Just I wanted to verify if the CoCo3 RF output was identical to the CoCo1 (in terms of ghosting effects) -- not a huge deal, just curious about how "backwards compatible" they were. I was also curious if you could "dual monitor" the CoCo with its multiple video outs.


As to the joystick: makes perfect sense - should have been obvious since there are no analog sticks for the Atari to be found. It might work for Baseball, but won't work for Shanghai.
 

Eudimorphodon

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I suspect I have one of the same RF connectors you're talking about lying around (a little dingus with an RCA plug on one side and a standard 75 ohm cable twist connector on the other? I've used it with various Atari consoles), if I stumble across it I'll try hooking up one of my CoCo3s just to sanity check, but I'm pretty sure, yeah, it should work unless something's horked on the CoCo end.

Honestly, though, it's not much of a loss because, yeah, the quality is horrible. Frankly even the composite output on the CoCo3 isn't great, I really kind of wish the machine had a switch on it somewhere to turn off colorburst so you could run it in monochrome for better clarity. I spent some time trying different color combinations and it was futile, 80 column mode was useless via composite even on a high-quality mono monitor because of the weird color palette.
 

voidstar78

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For reference, here is the cable and adapter that I am using for the CoCo1 RF output. [ I'm not actually using the Computer/Antenna switch-adapter; the end with the adapter piece connects to the CoCo, the other end goes straight into an old Samsung LCD TV that I found that has such an input ]

I figured this same cable would work on the CoCo3, but it isn't on mine. [ but the CoCo3 RCA video output is working for me, so I do know the CoCo3 functions fine -- the manual doesn't refer to any settings to switch between coax/RF video out vs RCA video out vs RGB video out, so I had thought perhaps each of those outputs are pumping signal simultaneously? ]
 

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vwestlife

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The CoCo 3 has composite video output, so why not use that instead? It's much higher-quality than RF.
 

voidstar78

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The CoCo 3 has composite video output, so why not use that instead? It's much higher-quality than RF.

Yep, I do. I was just curious on two things:

- Did the CoCo3 improve the RF video quality output over CoCo1? (aside from the other video improvements) That is, how "authentic" is the backwards compatibility -- can you get an equal "CoCo1-experience" using the RF-output on the CoCo3, or is it actually improved?

- Can you do "mirrored-output" to two screens, both the RF and composite at the same time? (one reason to do so is that in front of you'd have an operating screen near the keyboard, then remotely you could project the same video output to an audience further away -- another reason might be that I'm capturing the composite signal in a DVR-like capture device, but then using the RF signal to actually operate the system)


And a third reason would be:
- If I get a TV with no composite video input and only has RF in, could I still use my CoCo3 with it?


But either I'm misunderstanding the RF output of the CoCo3, or the one on mine just doesn't work. (I did try both CH3 and CH4)

Reference
 

twolazy

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I have a few coco joysticks I be willing to sell / trade if interested...and a 7? Port third party multipack and parts unit coco2 as well.
 
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vwestlife

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You can use the Coco 3's RF, composite, and RGB outputs all at the same time. If you're getting nothing out of the RF output on a setup that you know works with other systems, first try flipping the channel switch back and forth (maybe it has dirty contacts). If that still doesn't help, it has a faulty RF modulator.
 

voidstar78

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Thanks for confirming that it should work. I finally got back to the CoCo3 and just cleaned the RF contact a little bit -- and voila, it's working now with the same cable I use on the CoCo1.

So dirty contacts as suggested; Thanks!

And confirmed, it will mirror the outputs on RF and composite at the same time (as expected).
 

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mdh

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So, I have two Kraft joysticks, with male db 15 connector, I haven’t gotten around to replacing the connectors with din 4 (waiting on din connectors). Any thing I should look out for? I was planning on removing the db 15s and just replacing with din connectors.
 

Eudimorphodon

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So, I have two Kraft joysticks, with male db 15 connector, I haven’t gotten around to replacing the connectors with din 4 (waiting on din connectors). Any thing I should look out for? I was planning on removing the db 15s and just replacing with din connectors.

I hope you meant DIN6. The 4-pin connector on the CoCo is the serial port.

I've converted a late-model Kraft joystick using the instructions here (except directly replacing the DB-15 instead using an adapter, it seemed kind of pointless given the wiring has to change internally anyway) and the result works fine on both a Tandy 1000 and a CoCo. The thing I ran into is I had to shuffle the connections on the pot because the directionals were reversed. (The instructions in that post say you can just hook the unused terminal on each pot up to ground, but I think the Kraft joystick I used had +5 on the "sweeper" terminal, not the common. I just disconnected everything and reconnected it according to the schematics of an actual Tandy joystick.)
 

twolazy

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Havent forgot about you btw, have 1 joystick , cant seem to find my bin of tandy coco stuff, going to check the attic next week when it isnt freezing...

One I have is in awesome shape will get ya a picture when im not at work. =)
 
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