How does the CX-55 adapter affect the state of the 5200 when it's connected?

[+x=usr(1536)]

Something that's captured my attention recently is the CX-55 adapter - or, more accurately, some of the general concepts it uses.

 

One thing I'm not clearly understanding is what happens to the host hardware on the 5200 when the CX-55 is connected.  Is it halted, does it just sit there waiting for data, or something else?  My suspicion from reading through schematics is that it doesn't touch the host beyond power, audio, and video, but would be interested to know if it can or does access the 5200's hardware.

 

There may be some untapped potential in the way that that specific device works which might be applicable to other uses.

[leech]

On 9/10/2022 at 9:34 PM, x=usr(1536) said:

Something that's captured my attention recently is the CX-55 adapter - or, more accurately, some of the general concepts it uses.

 

One thing I'm not clearly understanding is what happens to the host hardware on the 5200 when the CX-55 is connected.  Is it halted, does it just sit there waiting for data, or something else?  My suspicion from reading through schematics is that it doesn't touch the host beyond power, audio, and video, but would be interested to know if it can or does access the 5200's hardware.

 

There may be some untapped potential in the way that that specific device works which might be applicable to other uses.

I just know that I read it'll toast 4 port 5200s if they haven't been updated... and mine hasn't so my CX-55 sits in a box.

[zylon]

To my understanding, the cx55 skips the logic side of the system entirely, making use of only one side the dual power circuits, video & logic. Unrelated, but I've often wondered about the possibility of making similar adaptors, to play more classic era system games through it.

[+x=usr(1536)]

38 minutes ago, zylon said:

To my understanding, the cx55 skips the logic side of the system entirely, making use of only one side the dual power circuits, video & logic.

This is what I thought as well, but I'm not sure as to why or from where that idea is in my head.  One of the 5200s here needs to be opened up anyway, so some probing is probably in order the next time it's on the bench.

38 minutes ago, zylon said:

Unrelated, but I've often wondered about the possibility of making similar adaptors, to play more classic era system games through it.

It's unfortunate that Atari never put a composite video input line on the expansion port: one of the ideas I'm kicking around is a way to run laserdisc games from cartridge using the original game's video, and that would have made things a lot simpler.

 

What I'm trying to avoid is running the game in emulation on a Raspi-in-a-cartridge and just using the 5200 for audio and video output.  I'd be fine with an ARM (or similar) handling video decoding and playback on the cartridge with the audio and video carried to the 5200 for final output, but only if SALLY was handling the game logic.

 

This is a lot easier said than done for a number of games, and specifically ones that rely on controllable sprites overlaid on LD video.  That said, it should be possible to take games that rely on timing-based movement (Dragon's Lair, Cliff Hanger, etc.) and have their original movement tables be processed on the 6502.  But if half the board is powered down, it's a moot point.

[leech]

1 hour ago, zylon said:

To my understanding, the cx55 skips the logic side of the system entirely, making use of only one side the dual power circuits, video & logic. Unrelated, but I've often wondered about the possibility of making similar adaptors, to play more classic era system games through it.

Huh, so couldn't you feasibly slap a 8bit computer cart adapter with joystick ports, and the option/select/reset/start buttons, then pass things through and essentially play games made for the 400?

[+x=usr(1536)]

56 minutes ago, leech said:

Huh, so couldn't you feasibly slap a 8bit computer cart adapter with joystick ports, and the option/select/reset/start buttons, then pass things through and essentially play games made for the 400?

Bear in mind that the 5200's ROM is different to the ones used in the A8, it lacks a PIA, and only has 16K of RAM.  To my mind, it would make more sense to implement a complete A8 on a compact board and just use the 5200 for power and A/V output like the 2600 adapter did.  But yes, it's a possibility.

 

Realistically, a 7800 adapter might be a better fit these days: it'd make the 5200 the one Atari system capable of playing titles from all three of Atari's dedicated 8-bit game consoles.  Doubt there's much demand for one, though.

[SoundGammon]

I have a CX-55 but I don't use it.

 

Basically, the 5200 is running but with no program.

 

All the chips are on and doing nothing!

 

Like turning on your stove and not cooking anything!

[Keatah]

Very much the same thing with the respective Intellivision and ColecoVision adapters/SystemChangers.

 

3 hours ago, x=usr(1536) said:

To my mind, it would make more sense to implement a complete A8 on a compact board and just use the 5200 for power and A/V output like the 2600 adapter did.  But yes, it's a possibility.

Then you need a keyboard, and SIO connector, and D-subs.. That's a lot of stuff.

 

3 hours ago, x=usr(1536) said:

Realistically, a 7800 adapter might be a better fit these days: it'd make the 5200 the one Atari system capable of playing titles from all three of Atari's dedicated 8-bit game consoles.  Doubt there's much demand for one, though.

Probably not. Then there is the matter of which 8-bit you go after, and how much memory, and all that.

 

Years ago I tried making an AIO rig. My own version of "UltraVision", but supporting even MOAR systems. Used hardware from all the popular systems on the market. Damn thing "collapsed" into its own complexity and under its own weight. It would take some 35 - 40 years till I ended up with the setup I so wanted as a kid.

Edited October 6, 2022 by Keatah

[+x=usr(1536)]

4 hours ago, Keatah said:

Then you need a keyboard, and SIO connector, and D-subs.. That's a lot of stuff.

Yep.  Thing is, it's probably inevitable given the parts of the 5200's architecture that may or may not be available for an expansion unit's use.

4 hours ago, Keatah said:

Probably not. Then there is the matter of which 8-bit you go after, and how much memory, and all that.

Agreed, and these are some of the very reasons why I was looking at the less-complicated laserdisc games as a possible use case.  Even then, i do recognise that it's all very much a solution in search of a need.

 

The 2600 adapter makes sense in the context of the time that it was released in.  Today, when you can pick up a 2600 Jr. for anywhere from free to $20 (with some shopping around), 7800s regularly crop up in the usual places for cheap-to-moderate prices, and emulation also exists, being able to use a 5200 for anything other than 5200 games isn't a total necessity.  It's neat that it can do it, but we have options now that just didn't exist when the system was current.

[+remowilliams]

9 hours ago, x=usr(1536) said:

Realistically, a 7800 adapter might be a better fit these days: it'd make the 5200 the one Atari system capable of playing titles from all three of Atari's dedicated 8-bit game consoles.  Doubt there's much demand for one, though.

It may be a bit silly, but it is cool : )

 

[+x=usr(1536)]

22 minutes ago, remowilliams said:

It may be a bit silly, but it is cool : )

Agreed on both counts   FWIW, I was actually thinking of doing it parallel to / resting on top of the 5200's case rather than creating another small skyscraper peripheral

[leech]

1 hour ago, x=usr(1536) said:

Agreed on both counts   FWIW, I was actually thinking of doing it parallel to / resting on top of the 5200's case rather than creating another small skyscraper peripheral

But... but... it needs to compete with the Sega Tower of Power!  If we could get an LD set up under it, a memory upgrade with the 2600 adapter on top, maybe it would look even more awesome than the Genesis, SegaCD, 32x and SMS adapter!

[+x=usr(1536)]

7 minutes ago, leech said:

But... but... it needs to compete with the Sega Tower of Power!  If we could get an LD set up under it, a memory upgrade with the 2600 adapter on top, maybe it would look even more awesome than the Genesis, SegaCD, 32x and SMS adapter!

I was thinking of topping it off with a Jag CD

[MrTrust]

12 hours ago, x=usr(1536) said:

Realistically, a 7800 adapter might be a better fit these days: it'd make the 5200 the one Atari system capable of playing titles from all three of Atari's dedicated 8-bit game consoles.  Doubt there's much demand for one, though.

 

Wow!  Imagine Big Sexy becoming the ultimate Atari machine!  I will have been vindicated for holding onto my personal machine since '86 that I bought at the Sears here in Port Townsend!  Now we just need every Colecovision game ported to the 7800 and I can retire every other machine but The Sexay One!  This is the greatest thing since atplaysoft ported Yars' Strike!

 

Just bustin' balls, Ray.

[SoundGammon]

There was a proto-type of the 2600/7800 adapter for the 5200. I think there's a pic of it at The Atari Museum.

[+x=usr(1536)]

Opened up the 5200 to chase down a snowy picture issue and took some measurements related to the CX-55 while I was in there.  Here's what I found:

• Regular cartridge: ANTIC, GTIA, POKEY, and SALLY all have +5V across Vcc and Vss.
• CX-55 adapter: only ANTIC and GTIA have +5V across Vcc and Vss.  POKEY and SALLY are at 0V.
• Atarimax SD Ultimate: ANTIC, GTIA, POKEY, and SALLY all have +5V across Vcc and Vss.

This is interesting because it suggests that the CX-55 adapter has a method of physically switching power to both POKEY and SALLY.  I'll need to sit down with the schematics and see if I can't figure out what's going on, but this could mean that rendering video on a cartridge-based coprocessor and streaming it down the cartridge port's composite input line may allow for mixed FMV and 5200 video with actual code executing on the 5200.  It won't be genlocked, but there may be a way to work around that.

 

No idea if this would work on a compatibility-modified 4-port, or a 4-port with an asterisked serial number.

 

The Atarimax is also drawing a fair amount of power when it's in use.  The VRs (7805s) are new as of about a year or so ago and I'm running a 12V / 5A power supply, but switching to Traco 2-2450 DC-DC switching regulators may be on the cards.

[+-^CrossBow^-]

On 10/8/2022 at 11:09 AM, x=usr(1536) said:

The Atarimax is also drawing a fair amount of power when it's in use.  The VRs (7805s) are new as of about a year or so ago and I'm running a 12V / 5A power supply, but switching to Traco 2-2450 DC-DC switching regulators may be on the cards.

On my bench supply the Atarimax Ultimate SD was only causing the system to draw about 750ma average? And that was with a 4 port unit I had just installed a UAV into as well. So far as I know the Amax being in used doesn't seem to take up that much more power to run than a normal cartridge does?

 

[+x=usr(1536)]

19 hours ago, -^CrossBow^- said:

On my bench supply the Atarimax Ultimate SD was only causing the system to draw about 750ma average? And that was with a 4 port unit I had just installed a UAV into as well. So far as I know the Amax being in used doesn't seem to take up that much more power to run than a normal cartridge does?

Very possibly.  I don't have a good way to measure current consumption at the moment, so all of this is based on observation of an also-needs-an-upgrade multimeter.

 

What I was seeing was voltage drop at SALLY across Vcc and Vss with the Atarimax inserted; there was also a noticeable increase in snow on the screen.  None of the retail 5200 cartridges I tested with exhibited this behaviour, so I'm currently working on the hypothesis that current draw may be at least a part of the reason for the snow issue.  If not, I'm looking at an internal problem with the RF modulator - and if that's the case, I'll just live with it since it'll soon be there solely in the event of needing a display output of last resort.

[leech]

1 hour ago, x=usr(1536) said:

Very possibly.  I don't have a good way to measure current consumption at the moment, so all of this is based on observation of an also-needs-an-upgrade multimeter.

 

What I was seeing was voltage drop at SALLY across Vcc and Vss with the Atarimax inserted; there was also a noticeable increase in snow on the screen.  None of the retail 5200 cartridges I tested with exhibited this behaviour, so I'm currently working on the hypothesis that current draw may be at least a part of the reason for the snow issue.  If not, I'm looking at an internal problem with the RF modulator - and if that's the case, I'll just live with it since it'll soon be there solely in the event of needing a display output of last resort.

Interesting.  That would explain why I thought the picture wasn't that bad when I first hooked up the 5200 to my TV, then later on I couldn't get a decent signal (presumably after I got the AtariMax Cart). 

 

On a slightly related note, I ended up ordering a Harmony Encore cart for a Heavy Sixer I bought that already had a composite mod done to it, but my Uno Cart for some reason just gave me a blank screen.  (Last time I used it, pretty sure it was working fine in my unmodified Heavy Sixer...)

[+x=usr(1536)]

1 hour ago, leech said:

Interesting.  That would explain why I thought the picture wasn't that bad when I first hooked up the 5200 to my TV, then later on I couldn't get a decent signal (presumably after I got the AtariMax Cart).

One thing I want to make sure everyone understands: I'm not blaming the Atarimax for this.  The snow is actually a lot worse with the CX-55 attached.  Having said that, there is a definite progression from retail cartridge to Atarimax to CX-55 in terms of how much the picture is affected.

 

This is why I'm eyeing something in my system as being out of spec.  If it all goes away with the UAV, at least I can say it's something in the vicinity of the RF modulator.  If it doesn't go away, then I may have to look deeper.

[leech]

7 hours ago, x=usr(1536) said:

One thing I want to make sure everyone understands: I'm not blaming the Atarimax for this.  The snow is actually a lot worse with the CX-55 attached.  Having said that, there is a definite progression from retail cartridge to Atarimax to CX-55 in terms of how much the picture is affected.

 

This is why I'm eyeing something in my system as being out of spec.  If it all goes away with the UAV, at least I can say it's something in the vicinity of the RF modulator.  If it doesn't go away, then I may have to look deeper.

Yeah I was trying to tweak and add a few things in between the RF modulator and the TV.  Mind you, I had an unmodified 4 port machine, and enjoyed the spark from plugging in the power through the RF cord.  Granted now it has a Sophia RGB in it.

[zylon]

On 10/8/2022 at 12:09 PM, x=usr(1536) said:

Opened up the 5200 to chase down a snowy picture issue and took some measurements related to the CX-55 while I was in there.  Here's what I found:

• Regular cartridge: ANTIC, GTIA, POKEY, and SALLY all have +5V across Vcc and Vss.
• CX-55 adapter: only ANTIC and GTIA have +5V across Vcc and Vss.  POKEY and SALLY are at 0V.
• Atarimax SD Ultimate: ANTIC, GTIA, POKEY, and SALLY all have +5V across Vcc and Vss.

This is interesting because it suggests that the CX-55 adapter has a method of physically switching power to both POKEY and SALLY.  I'll need to sit down with the schematics and see if I can't figure out what's going on, but this could mean that rendering video on a cartridge-based coprocessor and streaming it down the cartridge port's composite input line may allow for mixed FMV and 5200 video with actual code executing on the 5200.  It won't be genlocked, but there may be a way to work around that.

 

No idea if this would work on a compatibility-modified 4-port, or a 4-port with an asterisked serial number.

 

The Atarimax is also drawing a fair amount of power when it's in use.  The VRs (7805s) are new as of about a year or so ago and I'm running a 12V / 5A power supply, but switching to Traco 2-2450 DC-DC switching regulators may be on the cards.

the regular game cart, serves as part of the power circuit for the logic side of the system, at least on systems that can run the cx55. The cx55 just doesn't use those couple pins, and thus that side of circuit never closes, while in operation.

I have an Atarimax 128-in-1 flashcart, and my pic goes snowy after a time, or the colors change, like a bad VR would do. Playing physical cartridges, doesn't seem to do that. Of note, on my atarimax, certain games like Space Invaders, will get snowy after some good playtime, while others, like River Raid, will get the color change overheat effect.

[+x=usr(1536)]

2 minutes ago, zylon said:

the regular game cart, serves as part of the power circuit for the logic side of the system, at least on systems that can run the cx55. The cx55 just doesn't use those couple pins, and thus that side of circuit never closes, while in operation.

Appreciate the clarification - this is pretty much what I'd managed to figure out from the schematics, but hadn't had a chance to mention it yet.  Yours is a much better description of how it works than what I had kicking around in my head, though

[zylon]

11 minutes ago, x=usr(1536) said:

Appreciate the clarification - this is pretty much what I'd managed to figure out from the schematics, but hadn't had a chance to mention it yet.  Yours is a much better description of how it works than what I had kicking around in my head, though

a main difference in the original 4-port, is pin 24 of cart port. you have to cut the trace around it, for the cx55 to work. It's normally tied to GND.

My 5200 is an original "glossy" 4-port and still running the original switchbox, for reference.

Edited October 17, 2022 by zylon

[zylon]

On 10/5/2022 at 11:12 PM, x=usr(1536) said:

 

What I'm trying to avoid is running the game in emulation on a Raspi-in-a-cartridge and just using the 5200 for audio and video output.  I'd be fine with an ARM (or similar) handling video decoding and playback on the cartridge with the audio and video carried to the 5200 for final output, but only if SALLY was handling the game logic.

 

This is a lot easier said than done for a number of games, and specifically ones that rely on controllable sprites overlaid on LD video.  That said, it should be possible to take games that rely on timing-based movement (Dragon's Lair, Cliff Hanger, etc.) and have their original movement tables be processed on the 6502.  But if half the board is powered down, it's a moot point.

That's literally, what the cx55 does. It's a complete 2600, that just outputs into the 5200 video, and uses its' power supply.  With the popular "NES on a chip" setups being a possibility. You could have carts that have an entire system, and library, inside. Just a couple control ports and a reset button. The idea had come to me, after I got one of those little handhelds that runs crapload of old systems on it, and knowing how the cx55 actually worked. Market would be very low for such a thing though.

In the pre-internet days, we used to use those cx55 for parts, to fix 2600 systems. 

Edited October 17, 2022 by zylon