matze79 wrote:

Making a internal ISA Covox hmm, is it enough to hook up a Latch to LPT Base Adress ?
Or do they use additional parts ?

The Sound Master also has those parts.

I wonder if someone managed to find the original software for external Covox Master Key System II?

Hi. Not sure if this the right spot to post, but I found another Covox schematic.
At its core, it uses the usual 20k+10k resistor design, but it also has an LPT-powered amp.
http://rayer.g6.cz/elektro/covox.htm
Also linked is a program called CovoxMP3..

Jo22 wrote on 2020-08-06, 13:38:

Hi. Not sure if this the right spot to post, but I found another Covox schematic. At its core, it uses the usual 20k+10k resisto […]
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Hi. Not sure if this the right spot to post, but I found another Covox schematic.
At its core, it uses the usual 20k+10k resistor design, but it also has an LPT-powered amp.
http://rayer.g6.cz/elektro/covox.htm
Also linked is a program called CovoxMP3..

In that context you might also want to take a look at my SoundJr replicas. The schematic and layout files are on github.
The SoundJr devices provide volume control and are actually quite loud, especially for something that is port-powered.

matze79 wrote on 2018-07-08, 14:29:

Making a "internal" ISA Covox hmm, is it enough to hook up a Latch to LPT Base Adress ? Or do they use additional parts ? […]
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1All detailed PCBs of the Sound Masters and Voice Masters have a 74HC373 8-bit Latch and a resistor pack which can be used for Speech Thing output. I assume the Sound Master also has one

Making a "internal" ISA Covox hmm, is it enough to hook up a Latch to LPT Base Adress ?
Or do they use additional parts ?

An internal Covox already exists.
It was made by a German guy at an university and used a real DAC chip (C560 type)
from former East-Germany..

Link and picture : Re: Covox speech thingy!!!

Edit: A real LPT port isn't even required.
You can change the interrupt vectors that BIOS sets up for LPTx..
That way, you can design your Covox interface to appear at a different location by default.
All it needs is a little batch file and debug.exe .

Speaking of basic Centronics / LPT interfaces..
One of our forum members (133MHz) wrote a fascinating article once about a Famicom/NES clone with word processor and minimalistic parallel interface:

https://133fsb.wordpress.com/2010/03/21/famic … port-interface/

https://hackaday.com/2010/09/30/printing-from … clone-computer/

That being said, I don't know how much of this is applicable to the PC/XT platform.
A simple bus interface/address decoder might be needed, too.

Edit: @Benedikt Thanks a lot, I'll have a look at it. 🙂

Jo22 wrote on 2020-08-06, 14:27:

Edit: A real LPT port isn't even required. You can change the interrupt vectors that BIOS sets up for LPTx.. That way, you can d […]
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Edit: A real LPT port isn't even required.
You can change the interrupt vectors that BIOS sets up for LPTx..
That way, you can design your Covox interface to appear at a different location by default.
All it needs is a little batch file and debug.exe .

Already tested a few months ago 😀
works flawless.
but i remember some software won`t like it and go instead with hardcoded addresses.