Computer Audio Tape Formats

From: Dwight K. Elvey <dwightk.elvey_at_amd.com>
Date: Tue Dec 17 20:36:00 2002

>From: pete_at_dunnington.u-net.com
>
>On Dec 18, 0:37, pete_at_mindy wrote:
>
>> "101100" at 1200, you'll see it's actually a Manchester code:
>>
>> __ _____ __ __ _____
>> | |__| |__| |__| |_____| |
>>
>> --1-- --0-- --1-- --1-- --0-- --0--
>
>Oops, I take that back :-) Although the Sorcerer manuals describe it as a
>Manchester encoder/decoder, what it puts on the tape is FSK. I just
>checked the schematic and circuit description.
>
>Dwight hasn't exactly described Manchester encoding either, though.
> Manchester encoding puts the clock transition in the *centre* of each
>cell, and the polarity of the transition determines whether it's a 0 or a
>1. There's a phase shift at the cell boundary if necessary. His diagram
>*could* be Manchester encoding if you shift the 0s and 1s slightly to the
>left, except for the last bit. It should be (maybe 'd' for "down" and 'u'
>for "up" makes it more obvious):
>
> ___ _ ___ _ ___
> |___| |_| |_| |___|
>
> -0- -1- -1- -0- -0- -1-
> d u u d d u
>
>It's too late at night here, for any more of this :-)

Hi Pete
 Yes, you are correct. The difference in the Poly format
was between RZ vers NRZ. I think Manchester only refers to
the clocking, as you described.
Dwight
>
>--
>Pete Peter Turnbull
> Network Manager
> University of York
>
Received on Tue Dec 17 2002 - 20:36:00 GMT