Oric-1 Synthesis ..

Probably the most technical forum around. It does not have to be coding related, or assembly code only. Just talk about how you can use the AY chip to do cool sounding things :)
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ibisum
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Oric-1 Synthesis ..

Post by ibisum » Fri Feb 13, 2015 9:41 am

I just saw the demo here:

http://puremagnetik.com/post/1101849167 ... ellivision

.. and was wondering if anyone knew how they got the Portamento-like sound out of the AY chip .. its the second sound in the demo (which can't be seeked, unfortunately) .. I don't recall having access to Portamento - do you think this is a trick, or is there a hidden portamento in the AY chip?

I must say that Puremagnetik appear to have made some extremely fat sounds out of the AY .. its inspiring me to consider a synth program for the Oric ..

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Re: Oric-1 Synthesis ..

Post by Godzil » Fri Feb 13, 2015 11:20 am

First the AY is not alone on the board, and he use software after the AY so everything is possible.

By portamento, do you mean when it slide from one note to another? as a AY is programmed with somewhat near a frequency on the register, you can do whatever you want.

Apart from the low/high pass filter used on the sound recorded, there is nothing the AY is not able to do

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Re: Oric-1 Synthesis ..

Post by ibisum » Fri Feb 13, 2015 12:28 pm

Yes, that's what I meant by portamento .. so he's doing this by controlling the chip externally and not by a portamento/slide parameter in the AY .. bummer. Well, its still interesting to me to create an Oric-based synth .. the question then becomes, how to add MIDI to a stock Oric ..

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Re: Oric-1 Synthesis ..

Post by Godzil » Fri Feb 13, 2015 1:02 pm

You just need to add a serial port to the oric, and parse the midi protocol (it's quite easy to parse)

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Re: Oric-1 Synthesis ..

Post by ibisum » Sat Feb 14, 2015 4:24 pm

Yeah its the serial hardware that I'm unsure of .. would be especially nice if there were some way to do it with the Cumulus onboard ..

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Re: Oric-1 Synthesis ..

Post by ibisum » Mon Feb 16, 2015 9:38 am

I've since found out they made the AY demos with this wonderful device:

http://twisted-electrons.com/ay3/

I guess I'm saving up for one .. ;)

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Re: Oric-1 Synthesis ..

Post by Godzil » Mon Feb 16, 2015 11:08 am

there is no way to add a serial port "emulation" to the cumulus.

It would need a card with serial port between the oric and the cumulubus, like we always did.

There is no specific need to do for a serial port, a part to add a DIN connector, and some components to follow the midi hardware specifications (it is really simple) as the midi ports are just simple RS232 compatible hardware, running at a specific baudrate (which is not a classical one, but all RS232 chip are capable of using this baudrate)

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Re: Oric-1 Synthesis ..

Post by ibisum » Mon Feb 16, 2015 12:14 pm

I'm quite familiar with MIDI but not sure how to go about interfacing it directly to the Oric .. which I know has RS232, and can be programmed to handle MIDI's baudrate (31250) .. I guess I'll have a look at some of the existing serial schematics that are out there for the Oric and see what I can do ..

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Re: Oric-1 Synthesis ..

Post by Godzil » Mon Feb 16, 2015 12:32 pm

Google always have all answers:

http://www.teaser.fr/~amajorel/oricmidi/

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Re: Oric-1 Synthesis ..

Post by ibisum » Mon Feb 16, 2015 1:15 pm

Beautiful! I am going to build this! :)

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Re: Oric-1 Synthesis ..

Post by Godzil » Mon Feb 16, 2015 2:38 pm

Don't forget to add a passthroug connector to plug your cumulus/microdisc.

From the current schematics, it use the $032x register spaces where:

$0320 to $032F are used to read/write to the MIDI port
$0328 to $032F are used to read/write to the Minitel port

We have the following "registers" :

# Midi related
$0320, $0324 => DATA to read, or Write to MIDI
$0321, $0325 => Write: Reset, Read: 6551 Status register
$0322, $0326 => Write/Read Command Register
$0323, $0327 => Write/Read Control Register

# Minitel related
$0328, $032C => DATA to read, or Write to Minitel
$0329, $032D => Write: Reset, Read: 6551 Status register
$032A, $032E => Write/Read Command Register
$032B, $032F => Write/Read Control Register

Be careful to always use the same set of register (i.e not mixing use of register) as A3 is used to toggle the switch between MIDI and Minitel, so that a read or write to $0320-$0327 will switch to MIDI, a read or write to $0328-$032F will switch to minitel.

You can read in place of minitel "Standard RS232 port".

Also A2 is not used, this is why there is register duplication.

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Re: Oric-1 Synthesis ..

Post by ibisum » Mon Feb 16, 2015 3:04 pm

Thanks Godzil - The Passthrough connector would just be straight wired through, right?

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Re: Oric-1 Synthesis ..

Post by Godzil » Mon Feb 16, 2015 3:40 pm

ibisum wrote:Thanks Godzil - The Passthrough connector would just be straight wired through, right?
Yes

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