Tandy 3 Voice Sound - SN76489 ISA Soundcard Project

[root42]

Giving away my second Tandy card - thread here: viewtopic.php?f=5&t=62382

[Scali]

This is from my Lo-tech card with SN76489 chip: https://youtu.be/WD8snfTl8iI
Sadly the recording is very soft, but you can hear that the noise channel sounds pretty much 'correct', and different from yours.
I used the MODIAC.EXE patched version found on oldskool.org (so Maniac Mansion v1).

[root42]

Yeah, the V1 modiac.exe sounds correct on my card as well. The enhanced version sounds weird...

[Scali]

Yeah, the V1 modiac.exe sounds correct on my card as well. The enhanced version sounds weird...

Yea, I just tried it, it sounds strange indeed.
I didn't know there were two versions, and that they are so different, both in graphics and audio.

[root42]

New test: Zak McKracken V1

https://youtu.be/RYj5HdMNCpA

[matze79]

set your sn76489 output level lower to reduce noise level.

i already added some fixes to get the noise down in new version.
trying also to supply all ic's with own supply.

[Great Hierophant]

The differences between a true TI SN96489/96 and a clone NCR8496 or Tandy PSSJ are discussed here :

http://nerdlypleasures.blogspot.com/201 ... -chip.html

I assume everyone is using TI marked chips in their cards, but different chips appear to exhibit different behavior. As I indicated in that article, early Tandys can have the TI chips, but the majority of Tandy 1000s have chips with the NCR behavior. Whether you will get chips with the NCR behavior appears to be a roll of the dice.

[carlostex]

I noticed the problem with the noise channel when i was patching the games.

Maniac Mansion v1 works correctly because ripsaw8080 found a way to fix the noise channel via the patch. I don't remember the details though.

[root42]

Well, maybe we can diff the EXEs or ask ripsaw8080 then...?

[matze79]

i spend half the day rewiring my prototyp card and trying different approaches to make it less noisy.
it seems i had some success and full reroute is in progress,
also optimizing the card for "building kits" is in progress,
Placing all capacitors in same direction and ic's..

[root42]

And can you make it compatible with the Keystone bracket?

[matze79]

Keystone Bracket ?

[root42]

This one:

https://www.digikey.de/product-detail/d ... -ND/608463

Readily available, and one simply need to drill a hole for the audio jack...

[matze79]

in future it will also need a Hole for a volume knob

[root42]

in future it will also need a Hole for a volume knob

Also possible. For the Adlib it was the same.

[matze79]

Wow

there is software for pcm playback on sn76489

ftp://ftp.oldskool.org/pub/tvdog/tandy1 ... gimidi.zip

[Scali]

Wow

there is software for pcm playback on sn76489

Heh, the whole reason for my VGMPlay experiments was to get the PCM samples in some Sega games to play back correctly on a real 8088 with SN76489:
https://www.youtube.com/watch?v=gDMTU5nW0mE

And then the Skate or Die music:
https://www.youtube.com/watch?v=ARE6Bzs7Aj4

[JonSmith]

I am very much looking forward to buying one of these boards from you when they are finished!
It would be great if I could also buy one of those lotech isa compactflash pcbs from you together with the other board, if that is possible!

[root42]

A friend of mine made another ISA bracket for the sound card:

Tandy_Isa_Bracket.stl.zip

(4.47 KiB) Downloaded 8 times

Its advantage is that it is one piece and can be mounted with small screws and nuts.

I am using it on my own board:

[matze79]

Yeah nice, i had no time until now to continue with development but for future version there will be two volume knobs on the Backside, one for PC-Speaker and one for Volume.

Dreamblaster send me 3,5mm Audio Jacks with Screw, so i simply could mount the bracklet this way