[Coco] Orchestra 90CC

[Joel Ewy]

Bob Devries wrote:

> James,

> While it's true that the ROM in the Orchestra-90 does do what you describe, 

> any third-party and OS9 software does its own handling of the data, 

> including the timing between the sending of the data to the ports.

>

>   

Right.

> So unless the new hardware has some way of knowing how much time to insert 

> between "packets" of 2-byte stereo pairs, indeed the FIFO will make no 

> difference. In fact, I'd rather think that it would completely screw up the 

> timing that's necessary for the Orch-90 to work correctly.

>

>   

And that's what Kevin's original post said.  See below.
So how are such things done on PC sound cards?  Is there some logic for
pushing the data out at a defined sample rate, or is it all done in
software?

> --

> Regards, Bob Devries, Dalby, Queensland, Australia

>

> Isaiah 50:4 The sovereign Lord has given me

> the capacity to be his spokesman,

> so that I know how to help the weary.

>

> website: http://www.home.gil.com.au/~bdevasl

> my blog: http://bdevries.invigorated.org/

>

> ----- Original Message ----- 

> From: <jdaggett at gate.net>

> To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>

> Sent: Monday, January 29, 2007 6:42 AM

> Subject: Re: [Coco] Orchestra 90CC

>

>

>   

>> Kevin

>>

>> Adding a FIFO would do nothing to improve the performance. Audio tones are

>> genereated via the software in the 8Kx8 ROM. All the uP does is write to 

>> two

>> addresses an eight bit data. The writes are to two 8 bit latches whose 

>> outputs

>> have a 2R:R resistor ladder to perform digital to analog conversion.

>>

>> The way the progrma works the best method of improvement is to run the uP 

>> at a

>> faster speed. Then the software would need patching for timing issues.

>>

>> james

>>

>> On 27 Jan 2007 at 20:20, Kevin Diggs wrote:

>>

>>     

>>>  With all the recent discussion of the 90cc, I thought I'd ask:

>>>

>>> If this thing had had a FIFO <b>and some logic to send samples out at

>>> regular intervals</b> how much would that have aided performance? To ask

>>> another way, how much of a burden was it that the 6809 not only had to

>>> compute the samples but also had to deal with sending them out at the

>>> right time?

>>>

>>>       

(Emphasis added, JCE)

>>> kevin

>>>

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>>

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>

>

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