[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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>
>
>