[rescue] Current collections...

[Lionel Peterson]

> From: Joshua Boyd <jdboyd at jdboyd.net>
> Date: 2004/04/06 Tue PM 05:22:00 GMT
> To: The Rescue List <rescue at sunhelp.org>
> Subject: Re: [rescue] Current collections...
> 
> On Tue, Apr 06, 2004 at 11:57:43AM -0400, Dave McGuire wrote:
> > On Apr 6, 2004, at 11:02 AM, Lionel Peterson wrote:
> > >I like the idea of the older "historical" boxes, but
> > >the reality of storing programs on cassette tape is a
> > >challenge...
> > 
> >   That's what audio I/O and MP3 files are for.
> 
> Are MP3 files really good enough?
> 
> On the other hand, I bet you can lower the quality of
> an uncompressed stream a good bit, then use a lossless
> compression on that.

Well, let's do the math - TRS-80s saved programs and data at 1,500 bits per second (bps), now, if I assume 10 bits per byte of data (allowing for handshaking/etc.), that comes to 150 bytes per second - right?

I record MP3s at 160 Kb/s - so if I didn't change anything else, I'd be using 20,000 bytes of MP3 data to store 150 bytes of program data - each state change on the cassette would there have aprox. 20,000/150 samples = 133 samples per bit... I think that would be fine. If you step down the sample rate on the MPs to, say 48 Kb/s, then you are looking at 4,800 samples per 150 bytes of data, or 32 samples per byte.

The tolerances on the old cassette interfaces was far from precise, IIRC - so it should work, but oh the humanity! It would stillt ake 5 minutes to store 5 minutes worth of data... ;^)