Looking for a ST419

Ethan Dicks ethan.dicks at usap.gov
Fri Oct 31 17:05:57 CDT 2008


On Fri, Oct 31, 2008 at 09:16:47PM +0000, Tony Duell wrote:
> > > ISTR the bitrate from a ST412 drive was about 5 MHz...
> 
> The obvious thing to do is to sample the data stream (either from the 
> controller wehn writing/formatting, or from a good drive if you want to 
> copy it) at about 10 times the data rate (that's where the 'high speed' 
> requirement comes from) and record it in flash memory or something. Then 
> replay it back to the cotnroller for reading. It's doable, but getting it 
> all working at 50MHz is not going to be trivial.

I agree that a 50MHz digitizer is not a trivial device, but if it would
still work backed down to 25MHz or even a little slower, say 4x or 5x
the rate of the raw stream, there'd be a lot more margin to work with,
especially with modern high-speed microcontrollers like the Dallas
DS89C450-MNG.

You still need a local storage system fast enough to handle the bits once
they are collected and possibly partially analyzed/reduced.  That's one
arena in which a rotating disk is simpler than many solid-state solutions.

-ethan

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Ethan Dicks, A-333-S     Current South Pole Weather at 31-Oct-2008 at 22:00 Z
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Ethan.Dicks at usap.gov            http://penguincentral.com/penguincentral.html



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