[Coco] No MPI - any suggestions?

[Gene Heskett]

On Friday 05 October 2007, Bruce W. Calkins wrote:
>>> You have to tape over the CTS or SCS line on the cartridge -- the
>>> one that auto loads it (I don't recall which, but since you've been
>>> working on a proto board, you probably do) so the pak doesn't auto
>>> activate.
>
>On my first CoCo 1 I cut the wire into the cartridge header and soldered a
>switch  with wires in to control the auto-start.
>
>> I think in the short term cassette transfer is the way to go - via
>> soundblaster output of course. I'd imagine I could "CSAVEM" on the
>> emulator and "LOADM" at the same time on the real Coco?!? ...
>
>I have heard of trying that.  I haven't heard any success storys, yet.
>
>Bruce W.
>
I too have heard of that but haven't tried it.  If the tones are at the 
correct freqs there is no reason it shouldn't be hundreds of times more 
dependable than the average cassette player & tape combo ever was.

A story here.  I've had several CCR-81's & never could make any of them work 
dependably, seemingly it always took a virgin chicken sacrificed to make it 
work one out of 10 times.  KFC's stuff didn't seem to work, but then I think 
its false advertising to call that stuff chicken anyway.

Finally, in '86 or '87, someone needed something I had, and I rigged the 
cassette motor switch to my Sony metal tape deck, and made 3 or 4 copies of 
it using that.  Recording only one channel.  It seemed to work and I sent it 
off.  NDI who I sent it to now of course, but I got a message back over 
delphi a couple of weeks later that that tape was a loads perfectly the first 
time everytime tape.  Two secrets:

1. The CCR-81 and all its ilk all use 'dc bias' cuz its cheap, often saving 
battery power by using a permanent magnet swung against the tape for erasure 
when the record button is pushed.  It also gives a signal to noise ratio 
that's 30 db poorer than a decently designed 100 kilohertz sine wave bias and 
erasure generator can do. IOW, its 1944 technology & the only thing missing 
is the tape made of kraft paper.

2. because it uses only a small amount of the tapes magnetic ability, the 
playback levels are at best only about 1/4 that of the properly designed 
version.  Given the loss in signal to noise, its usually shot noises from the 
tape that messes up the recovery.

So feeding a coco from a decently composed output from a sound blaster card 
should get you perfect transfers every time. 

-- 
Cheers, Gene
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