Replacement for POKEY/DPC?

[Jaynz]

Just a simple question, since POKEYs are starting to get into short supply, is there a possibility of a new chip to be put on carts that can emulate POKEY and/or DPC to be put onto new carts that wouldn't require lots of careful reprogramming?

IE, let's say that I wanted to burn a 'modern' Ballblazer cart for the 7800. Is there a chip that can be taken 'off the shelf' today to handle the POKEY for the new boards?

 

 

[Rybags]

There are a number of partial Pokey implementations around, most miss one or more of the following features:

- keyboard scan

- serial I/O

- Pot scan

- extra waveforms available by combining 2 voices running at 1.79 Mhz clocking

- audio hi-pass filters

- 16-bit frequency audio by joining 2 voices

 

In a 7800 gaming context the first 3 don't matter, extra waveforms rarely used, hi-pass filters desirable but you can live without them.

 

I don't think anything "off the shelf" can replace Pokey. Possibly a PIC implementation is possible for some functions. AVR or ASIC easily but at some expense.

 

Shortage of Pokey chips themselves? I don't know... I've got something like 15 spare sitting here, purchased a bunch of 7800 NTSC Ballblazer boards a couple of years ago here.

[Lynxpro]

Sounds like a Kickstarter project if you ask me. Get Infogramestari and WB Interactive to sign off on it and go to Kickstarter to raise funds to manufacture a new round of Pokeys...or if you want pizzazz, go for a Quad Pokey run. Get the word out on here, other Atari boards, arcade gaming boards and YouTube and that could raise a bunch. Remember , it's not just 5200/7800 and A8 enthusiasts that need Pokeys...you have DIY musicians and also arcade enthusiasts with Quad Pokey arcade games buying boards like the Quad Pokey Eliminator and then competing with us enthusiasts in snapping up 7800 Ballblazer carts for chip sourcing.

 

I'm surprised the Commodore fans haven't already gone this route to acquire a new source for SID chips since that's dried up without parting out non-working C64s..,

 

 

[Rybags]

I suspect there's still plenty of spare Pokeys out there. And they're somewhat less popular than SID for DIY projects not involving the original host systems.

 

That and the fact SIDs were pretty much unique to C64 means they're in much shorter supply and yes, there is a market for cannabilized C64s and many C64s being sold around the place with no sound chip.

 

I wouldn't even bother contacting Atari or anyone, just make a replacement - I doubt there's any Patent protection, or much care factor on their part either.

 

But it's a limited audience and I don't know that much funding would come along.

 

Even the arcade games used a subset of it's features or at least in the case of Dual/Quads probably only used stuff like keys/pots on one of them.

[Bakasama]

I think there was a cheaper version of the POKEY called GUMBY planned at one point but that didn't go anywhere.

[Lynxpro]

I suspect there's still plenty of spare Pokeys out there. And they're somewhat less popular than SID for DIY projects not involving the original host systems.

 

That and the fact SIDs were pretty much unique to C64 means they're in much shorter supply and yes, there is a market for cannabilized C64s and many C64s being sold around the place with no sound chip.

 

I wouldn't even bother contacting Atari or anyone, just make a replacement - I doubt there's any Patent protection, or much care factor on their part either.

 

But it's a limited audience and I don't know that much funding would come along.

 

Even the arcade games used a subset of it's features or at least in the case of Dual/Quads probably only used stuff like keys/pots on one of them.

The SID is popularly because it has an extremely loyal [and vocal] following plus all of internet chat about it being better than the POKEY. But Quad POKEY is awesome and the audio in Atari's Star Wars Arcade Game is proof enough.

 

I mentioned going to modern Atari and WB Interactive not because of expired patents but due to any copyrighted code involved.

 

DIY is still a legitimate factor in favor of this. As stated in a thread on the A8 side, the A8 architecture is capable of accessing 16 POKEYs, or 4 Quad POKEYS. Just image 32 stereo POKEY voices in a homebrew project. That's worth funding.

 

As for the GUMBY, that was a GCC project and Curt's probably the only one who would know if anything was ever produced. The AMY would probably be easier to recreate than GUMBY.

[Rybags]

There's no actual "code" invoved with Pokey AFAIK. 6502 itself does have some ROM tables that describe what parts of the CPU get involved with each instruction.

 

Pokey I don't think needs any such thing. Serial is a simple shift register affair. Keyscan is just some counters with logic tests attached.

Pokey sound voices + timers are mainly counters with a flip/flop occurring at the voice output when zero is crossed.

Filters are just a selective XOR of the 2 voices involved.

Pots are read by timing how fast external capacitors reach a threshold voltage.

 

Really it's a fairly simple affair and most functions have been emulated 100% or near enough to that in software for years. Doing it in logic or software at a single chip level could be done likewise without infringing on anyone's IP rights.

Edited December 27, 2013 by Rybags

[AtariBrian]

I wouldnt doubt it if Brad at Best Electronics is sitting on thousands ... just saying

[Lynxpro]

I wouldnt doubt it if Brad at Best Electronics is sitting on thousands ... just saying 

Well, he does have an Indiana Jones warehouse setup with 30 year old crates that haven't ever been opened since they were sealed, right?

[Lynxpro]

There's no actual "code" invoved with Pokey AFAIK. 6502 itself does have some ROM tables that describe what parts of the CPU get involved with each instruction.

Pokey I don't think needs any such thing. Serial is a simple shift register affair. Keyscan is just some counters with logic tests attached.

Pokey sound voices + timers are mainly counters with a flip/flop occurring at the voice output when zero is crossed.

Filters are just a selective XOR of the 2 voices involved.

Pots are read by timing how fast external capacitors reach a threshold voltage.

Really it's a fairly simple affair and most functions have been emulated 100% or near enough to that in software for years. Doing it in logic or software at a single chip level could be done likewise without infringing on anyone's IP rights.

 

Interesting. So we just need a credible "organization" to go to Kickstarter and solicit funds to make a new run of Quad POKEYs then, eh?

 

Now trying to shove 1 or more of them (4?) into an A8/5200 or a 7800, would there be a potential RAM issue? It also seems as if Atari Coin/Games used a secondary 6502 to get them to cooperate with one another as well as other sound chips such as the YM 2151. Any thoughts?

[Rybags]

There's no "Ram issue" - there is memory mapping issue as each Pokey needs 16 bytes of address space.

 

From the onset Pokey was designed to be used in a dual config since it's got 2 Chip Select pins. In the case of using more than 2, it just involves some extra logic.

 

The second processor used by some games was probably more in aid of doing digital sample playback than anything else since it's a processor intensive task.

 

Realistically I don't see a big market for a quad Pokey replacement although if it could be made as a drop-in replacement for existing Pokey on the computer then there's probably a couple of hundred sales there if the price is right.

[Lynxpro]

There's no "Ram issue" - there is memory mapping issue as each Pokey needs 16 bytes of address space.

 

From the onset Pokey was designed to be used in a dual config since it's got 2 Chip Select pins. In the case of using more than 2, it just involves some extra logic.

 

The second processor used by some games was probably more in aid of doing digital sample playback than anything else since it's a processor intensive task.

 

Realistically I don't see a big market for a quad Pokey replacement although if it could be made as a drop-in replacement for existing Pokey on the computer then there's probably a couple of hundred sales there if the price is right.

 

True, assuming it's the same pin configuration. If it is [the same pin configuration], then I don't know why it wasn't a more popular mod in the A8 world back in the day.

[Rybags]

Extra Pokey/s isn't a plug/go situation. At the least you can piggyback but it's an inelligant solution.

Best solution is an daughtercard which plugs into the Pokey socket which is what most modern-day solutions are.

 

Also, to get stereo an entire extra audio circuit is needed.

 

Quad Pokey - the board seems to have a 40 pin arrangement that fits into a standard DIP socket. I would guess the pinout is altered though as the Chip Select lines that the single Pokey supply only support 2 chips.

As such, something would be omitted, I would guess most likely part of the serial I/O as it would be the least likely to get used in an arcade game.

 

Edited December 28, 2013 by Rybags

[AtariFriend]

I wouldnt doubt it if Brad at Best Electronics is sitting on thousands ... just saying

 

And there are millions more in other cheap ballblazer carts,ect. The POKEY chip is not

in short stock by any means. It will NEVER dry up with the number of pieces homebrew

fans will ever use.

[CPUWIZ]

 

And there are millions more in other cheap ballblazer carts,ect. The POKEY chip is not

in short stock by any means. It will NEVER dry up with the number of pieces homebrew

fans will ever use.

 

Too bad that the NOS stock of Ballblazer carts is no more, AFAIK. Or did they exempt those from the gold scrap?

[+Mitch]

 

Too bad that the NOS stock of Ballblazer carts is no more, AFAIK. Or did they exempt those from the gold scrap?

 

I heard that they didn't scrap the Ballblazer and Jinks carts but I didn't actually email or call O'shea's to verify it.

 

Mitch

[Jaynz]

And there are millions more in other cheap ballblazer carts,ect. The POKEY chip is not

in short stock by any means. It will NEVER dry up with the number of pieces homebrew

fans will ever use.

The problem is that you assume that the ONLY issue will be 'homebrew' usage against the supply, which is hardly going to be the case. The fact is that these chips are 30 years old and age is not that kind to microprocessors. Nevermind the number of people, even among game collectors, who will just 'toss out' carts that fail (even if the POKEY's are good) or just need to do spring cleaning. I mean, the number of 7800 carts 'out in the wild' in my area is just about ZERO, much less finding the right ones to strip, so the idea that the POKEY is in 'eternal supply' seems rather daft to me.

 

I'm not confident about being completely reliant to an ever-dwindling, non-replaceable stock of chips.

[Lynxpro]

 

I heard that they didn't scrap the Ballblazer and Jinks carts but I didn't actually email or call O'shea's to verify it.

 

Mitch

Is it the cartridge board in Jinks that makes it special? They seem to be popping up a lot on eBay lately.

[Lynxpro]

 

And there are millions more in other cheap ballblazer carts,ect. The POKEY chip is not

in short stock by any means. It will NEVER dry up with the number of pieces homebrew

fans will ever use.

Even if that were true, 7800 enthusiasts are competing for Pokeys with A8 owners seeking not only replacement POKEYs but also extras for Dual POKEY Stereo mods. Then there's DIY musicians using them for projects and also Atari Arcade Game owners sourcing them for replacements and they each could use 1, 2, or 4 POKEYs.

 

The supply isn't endless. And what about people who really like Ballblazer and who would rather not see those carts get destroyed?

[Trebor]

Taking a look at ebay right now:

http://www.ebay.com/sch/i.html?_trksid=p2050601.m570.l1313.TR2.TRC0.A0.Xballblazer+7800&_nkw=ballblazer+7800&_sacat=0&_from=R40

Not even close to cheap for a new Ballblazer. At least four are ~$30. Two of those four do not include shipping costs.

The "cheapest" option for loose/used Ballblazer games are not looking great either with prices range ~$7-10 dollars before shipping. There is only one used cart going for $5 with a $2 flat shipping charge.

So out of approximately a dozen or so listings for 7800 Ballblazer:

-Some costing $30 or more.
-Some running $10+ shipped.
-Some others between $12-16 shipped.
-Only one listing for a used cart with a 'rough label' costing ~$7 shipped.

Then with any of the above, you have to factor whose time/resources are being spent first taking apart the cart and desoldering the chip used on Ballblazer and then soldering it to a new board.

You're better off getting an unused, never soldered POKEY chip from Best Electronics or B&C for $10. Aforementioned supplies are undoubtedly finite though.

P.S. As we know, Commando is not even a consideration, especially with crap like this: http://www.ebay.com/itm/Rare-New-Sealed-Commando-Atari-7800-1989-Unopened-/301042138777?pt=Video_Games_Games&hash=item4617827e99

$200 already soldered/used POKEY chip available. Grab it while you can

[Lynxpro]

Extra Pokey/s isn't a plug/go situation. At the least you can piggyback but it's an inelligant solution.

Best solution is an daughtercard which plugs into the Pokey socket which is what most modern-day solutions are.

 

Also, to get stereo an entire extra audio circuit is needed.

 

Quad Pokey - the board seems to have a 40 pin arrangement that fits into a standard DIP socket. I would guess the pinout is altered though as the Chip Select lines that the single Pokey supply only support 2 chips.

As such, something would be omitted, I would guess most likely part of the serial I/O as it would be the least likely to get used in an arcade game.

 

 

I doubt the Serial I/O would be used by a 7800 though; it would only be used by A8s which means a daughterboard would still need a regular single POKEY present for functionality.

 

I noticed on the web that Atari Inc. apparently created a CMOS version of POKEY, a stereo POKEY named PORKEY, in addition to the QUAD POKEY chip.

[Rybags]

If you check a Ballblazer cart I suspect the bare minimum of traces are there to support Pokey.

2 * CS, Audio Out, 4 address lines, 8 data, Phi2, power, GND.

 

Most Pokey stereo plugin upgrades for the computer are similar - it's only been in modern times that people have had the desire to hookup some of the extras.

[Lynxpro]

If you check a Ballblazer cart I suspect the bare minimum of traces are there to support Pokey.

2 * CS, Audio Out, 4 address lines, 8 data, Phi2, power, GND.

 

Most Pokey stereo plugin upgrades for the computer are similar - it's only been in modern times that people have had the desire to hookup some of the extras.

Interesting. And obviously having the Serial I/O doesn't cause regular POKEYs from not working in the Atari arcade machines considering the Quad POKEY Eliminator boards work.