QSound and QPrint Interface

[Silvester]

Well, even if this is correct, I dont think that was the reason to use it. I don't know the price of the 6821 in the 80's but there is TTL chips like the 74LS245 that can do the same job, for a fraction of the cost, and that reduce the code need for use the sound chip, now you need to do one o more writes to the 6821 for select the BC1 & BC2 lines, and then do another writes to the sound chip.

QSound uses same interface for 6800 as suggested in http://dev-docs.atariforge.org/files/AY ... b-1979.pdf (page 43), I assume they just followed that. Interfacing 6821 on QL is easy, though QSound uses a crude method (IMHO).

Other 8-bit systems don't have this and don't suffer from any noise issues.

https://www.waveguide.se/?article=ymz28 ... -interface et al, experienced same noise issue I did when directly connecting to data bus. (BTW YMZ284 is just AY in DIP16).

There are also clues on the PCB that indicate me that noise was not a big concern, the number, position and value of the capacitors, for example are far from ideal.
There is no filter at output of the chip, ground backplanes, and the PCB traces, probably done at hand, indicate me that noise was not a issue.

Noise was not an issue most likely because it wasn't off data bus

[aalea]

Well, even if this is correct, I dont think that was the reason to use it. I don't know the price of the 6821 in the 80's but there is TTL chips like the 74LS245 that can do the same job, for a fraction of the cost, and that reduce the code need for use the sound chip, now you need to do one o more writes to the 6821 for select the BC1 & BC2 lines, and then do another writes to the sound chip.

QSound uses same interface for 6800 as suggested in http://dev-docs.atariforge.org/files/AY ... b-1979.pdf (page 43), I assume they just followed that. Interfacing 6821 on QL is easy, though QSound uses a crude method (IMHO).

That explain all, btw, I did not know this document, is much more complete that the datasheet I have, thanks.

Other 8-bit systems don't have this and don't suffer from any noise issues.

https://www.waveguide.se/?article=ymz28 ... -interface et al, experienced same noise issue I did when directly connecting to data bus. (BTW YMZ284 is just AY in DIP16).

There are also clues on the PCB that indicate me that noise was not a big concern, the number, position and value of the capacitors, for example are far from ideal.
There is no filter at output of the chip, ground backplanes, and the PCB traces, probably done at hand, indicate me that noise was not a issue.

Noise was not an issue most likely because it wasn't off data bus

I agree, That's true.

[Silvester]

I was considering whether to knock up a QSound board a few years ago but instead went with something a bit more ambituous (2x AY-3-8910, 2x SN76489, YMF262+YAC512).

I considered modding QSound to use one the spare port B outputs to switch AY input clock from E clock to something ZX compatible. But if you decide to try something like it on your QSound replica it would be trivial to add support to my player, then you'll have access to a few thousand files

(On my board I used 4066 cmos switches to configure ABC outputs, but it turned out to be just as easy to do it real time in player.)

poor quick photo

[NormanDunbar]

All this talk of AY-3-8910s is getting me all nostalgic.Many years ago, I built a sound effects card using one of these. I had no amplifier, so my transistor radio got dismantled and the sound output was connected to the volume control's middle connection. Power came from the radio's 9v battery and we had effects!

I've tried to remember which magazine I built it from:

* Everyday Electronics
* Hobby Electronics
* Practical Electronics
* Electronics and Computing

But, as much as I've searched archive.org, nada!

Them were t'days, as they appear to say in Yorkshire.

Cheers,
Norm.

[Derek_Stewart]

I have alot of these magazines, what year are we talking about.

[Silvester]

I've tried to remember which magazine I built it from

Maplin Electronics magazine did quite a few computer projects, IIRC more so than others.

BTW https://worldradiohistory.com/Home-UK.htm is a good source of back issues of magazines you mentioned.

[NormanDunbar]

Derek, sorry, I have no accurate year. Probably between 1980 and 1982-83. I knowvI was working in Inverness in the boatbyard at the time.

Sylvester, I never read Maplin Magazine, hoever, thanks for the UR|l, I'll have a scan later. Looks to be an interesting site.


Cheers,
Norm.

[Silvester]

Is it possible it was SN76477 chip you played with (at 9V) ? It was versatile and wasn't computer controlled like AY.

[aalea]

I was considering whether to knock up a QSound board a few years ago but instead went with something a bit more ambituous (2x AY-3-8910, 2x SN76489, YMF262+YAC512).

I considered modding QSound to use one the spare port B outputs to switch AY input clock from E clock to something ZX compatible. But if you decide to try something like it on your QSound replica it would be trivial to add support to my player, then you'll have access to a few thousand files

(On my board I used 4066 cmos switches to configure ABC outputs, but it turned out to be just as easy to do it real time in player.)

snap.jpg

WOW, this is too much chiptune in one card for me

I think that a second 2Mhz clock can be easy done with 1 74LS03 and a 2Mhz crystal, I will try to find one an check if work, anyway...

I'I can't test your player yet, but reading the instructions won't it be enough for this card to use something like EX AYplayer tunefile, QSOUND1T0F75000P0V255 ?

[Silvester]

I think that a second 2Mhz clock can be easy done with 1 74LS03 and a 2Mhz crystal, I will try to find one an check if work, anyway...

Yes, I used simple inverter (74HC14) with 1K from output to one side of crystal and 33pF to 0V, other side of crystal to input, with 4M7 across crystal. To switch between clocks I would have used 74HC00 with spare PB output controlling clock source with something like this:

Code: Select all

                        __
2MHz clock-------------|  )          __
                       |  )o--------|  )
+5v --<5K>--         --|__)         |  )o---------AY clock
           |   __    |        ------|__)
control----+--|  )   |        |
(PB?)      |  |  )o---        |
           +--|__)            |
           |           __     |
           -----------|  )    |
                      |  )o----
E clock---------------|__)

I'I can't test your player yet, but reading the instructions won't it be enough for this card to use something like EX AYplayer tunefile, QSOUND1T0F75000P0V255 ?

No, the QSOUND device is specific to QPC2v5. The real hardware will need to be written to explicitly.