while we are at it, here is a cable I did yesterday to chain my second tndy nano to an ews64xl for my basement setup :

Now I need to put the sticker on that computer case

matze79 wrote on 2020-11-28, 12:42:

Here is my Card installed in my 486: […]
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Here is my Card installed in my 486:

photo_2020-11-28_13-40-20.jpgphoto_2020-11-28_13-40-33.jpg

A Speaker + a 3 Pol Switch.

The Switch is used to Switch from 2C0h to 0c0h when i play Tandy Games.
And back to 2c0h for conflict free Operation afterwards.

I never realized the line-out amplifier of your tndy nano was so powerful it could drive that kind of speaker....

Don`t connect it to a Line In, only PCSPK in.

Its same Amplifer like Tandy uses, LM386.

matze79 wrote on 2020-12-06, 10:08:

Don`t connect it to a Line In, only PCSPK in.

Its same Amplifer like Tandy uses, LM386.

Wow, good advice ! Great thing I read that before I tested my setup. Although I'm pretty sure speaker-out is safe for line-in. My first tndy nano was connected to an awe32 spk-in. But this second one I intend to plug on ews64xl line-in. I'm not sure it support spk-in. Maybe I should lower the adjustable volume level potentiometer ? I left it at mid level.

EDIT : On secound thought... when you say "speaker-out" I assume you mean "pc-speaker-out" ? Maybe I can bypass that LM386 and feed the EWS64XL the LM386 input signal directly to the line-in of the EWS64XL ?

yes but if you bypass LM386 muting does no longer work, as LM386 ByPass Pin is pulled to GND to stop amplifer from working until ChipEnable is issued.
The MCU is also needed to survive bios scanning of lower port range without unlocking the Amplifier, as it introduces a delay of a few ms to allow SYSTEM POST accessing Devices.
This is specially useful on AT+ System as BIOS will access DMA Controller and unlock a Card on 0C0h making the muting Circuit useless.

I would connect it to PC-Speaker Input of the Soundcard or add a Second PC-Speaker to the Case.

I still hope we get that Serdashop Thing running, but due to current circumstances (corona shit and other delays) the slot cover still is not ready.

your card worked perfectly on ews64l on any position. I left the SMD variable transistor in the middle. I could not keep it though as it was too noisy. I doubt the 1.1 is any less. I plugged the SN76489 with two SAA1099 on a switched EQ so I can have both.

Thanks for making this card, I made a little 2 slot ISA riser for my IBM PS1 2011 and it works fine. A few issues when not initialised , and the TSR wont run on the the IBM but games that support the Tandy sound work .

Nice you like it,

https://github.com/matze79/Tandy-Nano

Now OpenSource.

Wow, thats great.

Thanks

Haha nice lighting, theoryboy! Do you lives in the eighties ?

ElBrunzy wrote on 2021-02-22, 15:08:

Haha nice lighting, theoryboy! Do you lives in the eighties ?

Permanently 😀

Hi matze79, thanks for the schematic. I do not want to disable amplified output. I am searching for ideal position to add line-out to the circuit. If I compare with similar project, I think it would be between C11 and R5. Although on my v1.0 version there is no R5. I pinout in yellow the audio-out of the SN7694 to the potentiometer signal and added white marker where I would tap. What do you think ?

This way I could internally daysi chain the TNDY Nano to the cd-in of another soundcard with peace of mind.

If you grab before LM386 muting will not work.

But yes its possible.

Thanks for the heads up, matze79. I did not noticed the job of the ATiny13. I looked at your circuit this way and now I believe the ATiny13 can reset the SN76489 via it's pin 7 and mute the LM386N via it's pin #3 and the help of the NPN at T1, right ? That's very clever from you and I just realize now you can control the card this way. I simply send the usual 9F BF DF FF at 2C0 should the rare time the card behaved erratically (hanging not for instance).

I see there is TINY13.BAS is that source code for SNDOFF.EXE ? I'm not sure I understand how TINY13.BAS work and how 3TOOL.EXE differ from SNDOFF.EXE. With source code I understand 3TOOL.EXE reset the SN76489 via 9F BF DF FF at 2C0 (in my AT case). But does SNDOFF.EXE reset it with !CE pin of the SN76489 ? I wonder if the LM386 mute work on 1.0 board since after running "SNDOFF.EXE" I can play music from the SN76489.

In all case I rarely needed them since your card work great for what I use it for. With the line-out before LM386 grab, I will be able to mute it on the receiving soundcard since it have a mixer.

No TINY13.BAS contains BASCOM Sourcecode for Attiny13.

It controls LM386 via ByPass Pin, if bypass is pulled to GND it mutes the Amp.
and watches for Reset, if System Reset occurs it restarts the MCU.
There is also a Timeout in the AVR Program, to ensure with Card on 0C0h it does not unlock during POST of the System.
Because AT Systems will access DMA #2 Controller on Boot.

3TOOL or SNDOFF is almost the Same, it just sends Commands to the Chip to set Volume of the Chip to 0

Ah it all make sense now ! I was wondering how the ATiny was told by the ISA bus to reset the SN76489.

Thank you a lot for answering my questions and the release of the schematic. You see, I learn so much studying your project, it goes far beyond the scope of just enjoying SEGA Master System titles on hardware synthesizer.

This is not a new build, but in my collection there is a Preton Technology (Adlib clone) ISA-8 soundcard which someone has modified by adding a small home-made PCB to it (for enhanced amplification, I think).

On the v1.0 card I hooked the ground to the lower (the one next to "C12" silkscreen text) pin of C12 (which is really R2), L+R are before the added 10k resistor (between the pcboard and the resistor) at the middle leg of the 10k trimpot. Thus providing a safe line-level to the host card via a molex mpc2 audio connector.

Here you can see a tndy nano v1.0 connected to it's host soundcard. I'm not sure what is the added value of this document but I like this kind of geeky stuff.

I've finally put one of these together and I can't get any audio from it. My early prototype Pearce tandy sound card works fine but this is just dead silent.

Is it possible the little PIC controller wasn't programmed? Is there a TSR to unmute it or something?

*edit*
I realized my programmer can read those attiny devices, and it seems A-OK (re-programmed just in case) but still nothing.

I've tried COh and 2COh, neitehr work with SBVGM on the nano but both are fine with pearce card...

OK so it IS working, it's just EXTRAORDINARILY quiet compared to the Pearce board. I pulled the PIC completely and I can barely hear the default SN76489 noise and music playing with speakers turned all the way up, which is ear-splitting when using the Pearce board. Maybe the variable resistor thingy is the wrong type, or the LM386 amp is bad?

I have swapped the LM386 with a new part, swapped the SN76489 with another known-good part, and triple-checked the resistors and capacitors against the parts list provided.