Re: TI-H: I need help with software for an 8-bit sound cart

To: ti-hardware@lists.ticalc.org
Subject: Re: TI-H: I need help with software for an 8-bit sound cart
From: "Ed Plese" <eplese@Lnd.com>
Date: Tue, 19 Aug 1997 22:01:12 +0000
Comments: Authenticated sender is <eplese@igs1.lnd.com>
Reply-To: ti-hardware@lists.ticalc.org

> I don't know if it matters, but an alternate solution to produce 8 bit
> sound
> is to connect a PCF8574 8-bit I2C expander to the calc and then either a
> "Covox" style resistor network or a real 8-bit DAC to that chip. I have
> both the PCF and a homemade Covox, so I might test that some day.
> 
> It would be best to have one 8-bit sound standard. I don't know anything
> about Microwire or your chip, so I can't say which solution is better,
> but one of them should be trashed so we don't have competing standards,
> we don't need them in this kind of a restricted environment...
> 
> Remember though, that you can produce at least 2-bit sound with the bare
> link port, do we really need 8 bits?
> 
> (I saw a .ZIP packet on ticalc.org that advertizes 4-bit sound...wonder
> how that works. I haven't got time and interest to check that out,
> though...)
> 

Yes, the sound needs to be 8 bit or else it will sound completely 
horrible.  I think that the best solution would be to use a serial 
DAC, just like the ones used in most portable CD players.  I can't 
remember where, but somewhere on the WEB I saw some datasheets for 
one of these chips.  This would make the sound adapter very simple.

-Ed