[rescue] Current collections...

[Dan Williams]

Lionel Peterson wrote:

>>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... ;^)
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>
>  
>
I haven't got around to trying it yet, but a few people playing around 
with the amstrad cpc's and (I think) spectrums. Have done exactly this, 
sampling tape programs to wav's or onto cd's. If there isn't too much 
copy protection on the tape,, you can play it straight back into the 
machine (using one of those in car cd kits,  the tape with the jack plug 
on it). They have  had problems with mp3's, but if they leave it as a 
wav it can be speeded up to 3 or 4 times the original speed and it still 
loads. Good for programs that used to take 5 mins or so to load.

Dan