Jump to content
DrVenkman

POKEY alternatives?

Recommended Posts

So here's something that's kind of been bouncing around my head for awhile, and I finally decided to see if the 7800 cognoscenti have ever given something like this much thought ...

 

We all know that POKEY chips are getting rather pricey, and certainly add quite a bit to the cost of homebrews that use it. But at the same time, there are projects in other communities that create combos that never existed BITD, such as fitting SID chips to non-Commodore computers, Curt's XM project which aims to add not only POKEY but also a Yamaha YM synth chip, etc.

 

So my actual question is, has anyone ever taken a survey of available 8-bit +5V compatible sound or synth chips, found one that can be bought readily for just a few bucks, and then tried to design a board that can use it in lieu of requiring increasingly-expensive POKEY chips? I could foresee a game that used a YM chip for game music and TIA for the basic sound effects (much like Commando did with POKEY music and TIA game sounds).

 

Similarly, would it be possible for someone to implement something like the DPC bit-banging sound chip solution David Crane came up with for the 2600 in 7800 games?

 

There's GOTTA be a way for the 7800 to get some audio-love here in the modern era. :)

  • Like 5

Share this post


Link to post
Share on other sites

I thought about having a CEM3394 chip in my homebrew carts, but doubt that they are still being made today. (That chip was used in Bally Sente's arcade hardware and at least one Sequential Circuits synthesizer.)

  • Like 1

Share this post


Link to post
Share on other sites

I'm all for upgrades or replacements, but we really need the HOKEY.

 

That's not to say that there isn't room for other solutions, but given that the POKEY also handles inputs and is used across a wide range of Atari hardware (both consumer and coin-op), having a working replacement for it is vital to hardware preservation.

 

Curt released the original POKEY scehmatics in November of 2016; hopefully that will lead to HOKEY seeing the light of day. Hell, even if it's implemented on an FPGA or similar, it would at least give an option (and conceivably could be done as a cut-down version of the QPOKEY).

Edited by x=usr(1536)
  • Like 4

Share this post


Link to post
Share on other sites

Wasn't someone making POKEY clone (HOKEY) a while back? Did that go anywhere?

batari never updated its status after announcing in the public forum.

 

The cartridge port is designed to have other sound chips, GCC's sneaky plan designing the Atari 7800 for Atari was they were making the successor to Pokey, a low cost, high performance sound chip, GUMBY, which could also be placed in 7800 cartridges. They had planned to make a fortune by requiring Atari to buy their new sound chip, but the project was canceled when Atari was sold to Jack Tramiel.

 

The 7800's TIA is the same as in the 2600.

It is bit-banging sampled speech with the screen on is in Bob DeCrescenzo's 7800 Astro Blaster Title Screen. The only reason that game didn't contain all the Arcade's samples was that he wanted to keep it a 48K cartridge, later saying that it was stupid not to just make it a larger cart initially because there's not my difference in cost. SpiceWare managed to get every sample in Draconian at a ROM cost of 4.5K.

 

So everything from beeper/squeeker 1-big music, to speech samples, to DPC bit-banging sound is possible on both the TIA and Pokey chips.

Share this post


Link to post
Share on other sites

I'm all for upgrades or replacements, but we really need the HOKEY.

 

That's not to say that there isn't room for other solutions, but given that the POKEY also handles inputs and is used across a wide range of Atari hardware (both consumer and coin-op), having a working replacement for it is vital to hardware preservation.

 

Curt released the original POKEY scehmatics in November of 2016; hopefully that will lead to HOKEY seeing the light of day. Hell, even if it's implemented on an FPGA or similar, it would at least give an option (and conceivably could be done as a cut-down version of the QPOKEY).

 

Per some of the posts about HOKEY over the years, it's NOT a full POKEY clone; it is intended for sound generation only. While undoubtedly useful for homebrew 7800 games, it won't help much at all for A8, 5200's and arcade game repair preservation.

  • Like 1

Share this post


Link to post
Share on other sites

 

Per some of the posts about HOKEY over the years, it's NOT a full POKEY clone; it is intended for sound generation only. While undoubtedly useful for homebrew 7800 games, it won't help much at all for A8, 5200's and arcade game repair preservation.

 

Good point; I'd forgotten about that. Take HOKEY in this context to mean, 'generic full-capability POKEY replacement,' then ;)

Share this post


Link to post
Share on other sites

 

Per some of the posts about HOKEY over the years, it's NOT a full POKEY clone; it is intended for sound generation only. While undoubtedly useful for homebrew 7800 games, it won't help much at all for A8, 5200's and arcade game repair preservation.

 

Ahh - that's different than what I thought the intent was to essentially make POKEY sound widely available again

Share this post


Link to post
Share on other sites

I hate it when scarcity and economics conspire like this ...

 

I understand that demand for an 8-bit sound chip must be miniscule

I understand that manufacturing any custom hardware has got to be expensive, especially in small batches

 

Has anyone guesstimated how much it would cost to reverse engineer the POKEY and make enough to last a long time, say 5000 or so of them?

 

I fully grasp that the answer is probably "too much to be worth the effort," but I'm curious how bad it might be.

  • Like 1

Share this post


Link to post
Share on other sites

I hate it when scarcity and economics conspire like this ...

 

I understand that demand for an 8-bit sound chip must be miniscule

I understand that manufacturing any custom hardware has got to be expensive, especially in small batches

 

Has anyone guesstimated how much it would cost to reverse engineer the POKEY and make enough to last a long time, say 5000 or so of them?

 

I fully grasp that the answer is probably "too much to be worth the effort," but I'm curious how bad it might be.

 

 

Everything was fine and dandy on the POKEY front until O'shea smelted down the NOS Ballblazers by the thousands.

  • Like 1

Share this post


Link to post
Share on other sites

There's a POKEY replacement chip entry in this year's ABBUC contest. Probably overkill for a 7800 as a "sound only" version would probably be sufficient for the 7800, but might still be the future. Details will have to wait until the end of October as there are some restrictions on what you can publish/sell before the contest is over.

 

Sorry, just saw that there is a thread on this in the 7800 forum already.

 

Buying a couple hundred of those O'Shea Ballblazer carts back then for a buck each would have been a sound investment....

Edited by slx
  • Like 1

Share this post


Link to post
Share on other sites

There's a POKEY replacement chip entry in this year's ABBUC contest. Probably overkill for a 7800 as a "sound only" version would probably be sufficient for the 7800, but might still be the future. Details will have to wait until the end of October as there are some restrictions on what you can publish/sell before the contest is over.

 

Sorry, just saw that there is a thread on this in the 7800 forum already.

 

Buying a couple hundred of those O'Shea Ballblazer carts back then for a buck each would have been a sound investment....

 

I don't even care to admit how many I tossed in the garbage as all I wanted them for was the cartridge shell. It was too much of a PITA at that time as I didn't have any use for 100's of pokeys. I was killing those bad boys 72 at a time when I was going through cases of them. Some other hardware guys on this forum did the same thing and in much higher volume that I ever did. Hindsight is always 20\20. I think Oshea's still has some but they are holding onto them or something. There is less tha 10k of them left. Weather that is across all the 7800 (and 2600) titles they had I do not know. They started out with over 250k of them if memory serves.

Share this post


Link to post
Share on other sites

So my actual question is, has anyone ever taken a survey of available 8-bit +5V compatible sound or synth chips, found one that can be bought readily for just a few bucks, and then tried to design a board that can use it in lieu of requiring increasingly-expensive POKEY chips? I could foresee a game that used a YM chip for game music and TIA for the basic sound effects (much like Commando did with POKEY music and TIA game sounds).

 

Similarly, would it be possible for someone to implement something like the DPC bit-banging sound chip solution David Crane came up with for the 2600 in 7800 games?

 

There's no point to a DPC approach. That's really only useful on the 2600, which doesn't have a sound line on the cart pinout. It's very CPU intensive to update TIA like that, and not a worthwhile tradeoff on the 7800. The intensiveness of this approach is why almost all action stops in 7800 games when they play samples.

 

I've given alternative sound chips a lot of thought as well, so apologies in advance for the forthcoming wall of text.

 

I think a modern design sound chip is a non-starter. The category of "sound chip" sort of shifted, so modern sound chips are more specific sound-task chips, like DACs, MP3 decoders, etc. These have assumptions on bus widths, speeds, hand-holding, and support circuitry that will be impractical on the 7800. If someone has counter-examples, I'd love to hear them.

 

The Hokey ARM design is interesting, but a bit tricky to pull-off in practice. I'm pretty sure it's running at a faster speed than the 7800, and dynamically working the address and data lines, similar to how a Harmony cart works them. This raises the bar for taking on this sort of solution.

 

I think the FPGA route is going to be prohibitively expensive for a while, especially when you factor in more than just the parts cost. One has to factor in defects, oopses, handling, etc.

 

So far as your "survey of 8-bit +5v chips", I think the PSGs and FM chips on this list of sound chips is a good starting point. The trick would be to find one that's cheap, and available in sufficient quantity for the supply and price to remain stable over the long haul.

 

As much as I'm looking forward to the YM2151 in the XM, I think FM synthesis might be a poor choice for a general Pokey replacement. There's a lot more setup for FM sounds, and more theory involved in getting sound out.

 

One candidate is the AY-3-8910/YM2149, a 3-channel PSG design that otherwise seems fairly similar to Pokey, in general approach. Including clone chips, it was used in several arcade games, several 8-bit computers, the Intellivision, and the Atari ST. It sounds pretty good, too: 1, 2.

 

I have no idea on how common this chip is now, but it can be had for a couple bucks on ebay. According to the AY-3-8910 wikipedia page, clone chips are still being produced.

 

Is 3 voices a non-starter, and if so, do we need 2 chips on a cart? Who will build the new cart design? If someone builds it, will they come?

  • Like 3

Share this post


Link to post
Share on other sites

Who will build the new cart design? If someone builds it, will they come?

 

A.) Not me.

B.) No.

  • Like 1

Share this post


Link to post
Share on other sites

A.) Not me.

B.) No.

:thumbsup: Yeah, for sure. Just to be clear, I wasn't thinking it should be you, or even indirectly asking. You're obviously more than capable, but I wouldn't wish another heavy-lift on you, or another large "investment" in parts. The last couple of questions at the end of my post were mostly rhetorical, raising the whole chicken+egg thing.

 

I think instead of expecting a hardware superman to show-up, invest time and money, and finish projects from concept to product, we as a community need to figure out a better way. I'm not sure what that exactly would be. I noticed the A8 scene has a lot of open designs, which get implemented by different folks. This at least spreads the work and risk around.

  • Like 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...