Cassette Baud...

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Rink
Posts: 236
Joined: Mon Sep 05, 2011 7:01 pm

Cassette Baud...

Post by Rink »

Quick question, but I've had difficulty finding the information from Google: what's the (approximate is fine) baud rate of the Dragon 32's cassette interface?

Cheers.
Dragonizer
Posts: 6
Joined: Mon Jul 09, 2012 3:13 pm

Re: Cassette Baud...

Post by Dragonizer »

According to Dragon User Magazine Issue September 1985, page 19 it's 1500 Baud.
Rink
Posts: 236
Joined: Mon Sep 05, 2011 7:01 pm

Re: Cassette Baud...

Post by Rink »

Really? Seems slower than that to me. :)

Cheers mate. Much appreciated.
Sarah
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Re: Cassette Baud...

Post by Sarah »

The symbol rate is variable, since it takes only half as long to transmit a "1" bit compared to a "0" bit. I wonder if the quoted baud rate accounts for this (perhaps being an average), or whether it even makes sense to have a single value rather than a range?
prime
Posts: 266
Joined: Fri Apr 10, 2009 1:40 am

Re: Cassette Baud...

Post by prime »

Sarah wrote:The symbol rate is variable, since it takes only half as long to transmit a "1" bit compared to a "0" bit. I wonder if the quoted baud rate accounts for this (perhaps being an average), or whether it even makes sense to have a single value rather than a range?
Really? I always thought it was 1 cycle of 1200 or 2 cycles of 2400 for each bit so that the bit time is the same.

Cheers.

Phill.
zephyr
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Re: Cassette Baud...

Post by zephyr »

This is fully explained on page 213 of Inside The Dragon.
Sarah
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Re: Cassette Baud...

Post by Sarah »

prime wrote:
Sarah wrote:The symbol rate is variable, since it takes only half as long to transmit a "1" bit compared to a "0" bit. I wonder if the quoted baud rate accounts for this (perhaps being an average), or whether it even makes sense to have a single value rather than a range?
Really?
Yep!

Try filling a large area of memory with $FF and then an equal amount with $00; it's easy to hear that the $FF blocks are half the length of the $00 blocks!
zephyr wrote:This is fully explained on page 213 of Inside The Dragon.
Well spotted...
"the effective data transfer rate from Dragon to cassette recorder is 1800 bits/second as, on average, there will be an equal number of ones and zeros recorded for a program or data file"
Presumably Brian Cadge gives a lower approximate figure in his article to adjust for overheads.
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