I am interested as well, I've been monitoring the thread but don't have anything to contribute...
IMHO a person that understands and can hack games will be needed here as well...

keropi wrote:

I am interested as well, I've been monitoring the thread but don't have anything to contribute...
IMHO a person that understands and can hack games will be needed here as well...

We will see, if the ISA prototype works well on AT systems with the sound generator responding to C0h calls, then we might only need to hack games that require specific Tandy BIOS extensions and/or graphics.

Even so, it would be simpler to create a TSR that emulates this rather than try to patch a bunch of games. We will see that.

Protected mode would be needed to do any kind of port remapping.

pearce_jj wrote:

Protected mode would be needed to do any kind of port remapping.

Yes, XT systems will unfortunately not be able to enjoy TSR enhancements if we decide to do them. So only games that support 3 voice sound + CGA/EGA/VGA can be enjoyed. Still pretty much worth it.

Got a very detailed reply from Mark Seibert who worked at Sierra On-Line at a time when the Tandy 3-voice was still largely supported.
These are excerpts from a longer series of questions that Mark Seibert was very courteous in accepting to answer.

Concerning their workflow with music composition and adaptation for lower fidelity devices, Mr. Seibert had this to say :

My first task was to take William Goldstein’s music written for the Roland MT-32 and re-write it for the Adlib, IBM Music Feature, Tandy 3 voice, and PC speaker. This involved working with programmers to get me access to the hardware software interface so I could program new sounds and have real-time connection to the devices much like just playing a connected synth.

When asked about how they wrote and listened to music for the Tandy 3-voice :

We developed a way to connect every device to respond to the MIDI messages from the MPU-401. For example, the composition system with sequencer was attached to the other another PC (Like the Tandy) via a MIDI cable out of one system and into the other. The Tandy system would have our receiving software running that would allow us to play it just like a connected synth.

And finally, concerning a potential "Dev Board", Mr. Seibert provided the following remark :

Nothing was provided by Tandy (Radio Shack) other than just the computer itself.

So... about this :

carlostex wrote:

Apparently they did have development boards, including the PSSJ and SN74689 (or should it be the NCR clone?). Commercially, i don't think they did.

If there actually WERE any dev boards, they were not made available to the music department at Sierra On-Line so I'm really starting to doubt their existence. Shame!

So there you go, here was my small not-too-technical contribution for this project 😀

Sierra and Tandy had a longstanding relationship and Tandy computers were apparently pretty commonplace at Sierra. When they had the development platform, I would think there was less need for the development card.

...interesting thread.

If a hardware Tandy GFX/SND Card will be possible, then the general Problem will still be "getting the tandy-versions" of the Games.

Thanks Beegle, always great to hear something from the people who actually worked close to the metal.

dr.zeissler wrote:

...interesting thread.
If a hardware Tandy GFX/SND Card will be possible, then the general Problem will still be "getting the tandy-versions" of the Games.

Main objective as of now, is to make games that could use 3 voice Tandy chip sound with CGA/EGA/VGA play Tandy 3 voice via hardware. We will think about the other stuff later.

Need a schematic for an NTSC clock generator - sound chip input is for a clock (not a crystal) according to the datasheet.

pearce_jj wrote:

Need a schematic for an NTSC clock generator - sound chip input is for a clock (not a crystal) according to the datasheet.

Would a 74LS74, connected to the OSC signal and made to divide by 4 work? Sergey's ISA OPL2 board has the connections and both sound chips use a 3.58MHz clock.

Looks good, thanks!

Please have a look at the schematic here.

This is a very early cut, sorry I've not even put any text around it. Currently this is only listening on C0..C7 per the Tandy adapter. I've included a rudimentary mixer to enable the PC speaker signal to be fed to the board, and the resultant combined signal back to the PC speaker.

Any feedback would be very welcome! It's much quicker to make any changes now before I start the PCB routing.

A few comments :

1. I think A2 should not be attached to the address decoder. If I have my binary correct. leaving A0 floating gives you C0-C1, A1 gives you C0-C3 and A2 gives you C0-C7.

2. I also think there should be staking pins on the lines that compare A7 and A8 to +5v or GND so you can put this card at 1E0, just in case it conflicts with the 2nd DMA controller on AT class systems.

3. Your PC Speaker headers should have four pins, not three.

4. Is there an external audio out on this card? I cannot tell from the schematic.

Thanks, I will make the changes. External out could be eg 3.5mm if you like, currently it's just screw terminals and the header.

But, aren't we missing the 3 channel sampled audio DAC?

pearce_jj wrote:

But, aren't we missing the 3 channel sampled audio DAC?

The Tandy PSSJ circuitry is impossible to source, as far as i know.

Either we devise an hardware compatible solution or emulate the Tandy DAC to play via a sound blaster. Hardware would be better of course.

pearce_jj wrote:

External out could be eg 3.5mm if you like

I think everybody agrees that that's a requirement.

carlostex wrote:

The Tandy PSSJ circuitry is impossible to source, as far as i know.

Either we devise an hardware compatible solution or emulate the Tandy DAC to play via a sound blaster. Hardware would be better of course.

Maybe it can be emulated in hardware? With something like a PIC or another cheap microprocessor?

It would be great if someone could post the details about the Tandy DAC from a programmers perspective. Maybe we can build in the same functionality.

pearce_jj wrote:

It would be great if someone could post the details about the Tandy DAC from a programmers perspective. Maybe we can build in the same functionality.

I'm sure Great Hierophant might have some info as he owns Tandy's and i will contact Cloudschatze and Trixter.

Great, thanks.

If Beegle doesn't mind asking Mr. Seibert if has any kind of PSSJ documentation i guess that would help too.