On Dec 17, 16:00, Dwight K. Elvey wrote:
> Here is one that is even a little different still.
> It is what is called Manchester encoding, using biphase
> clocking. You don't indicate 1 or 0, you indicate a change
> by a quick clock and no change by a long clock.
> This is the type of encoding used on my Poly88 for
> what they call PolyPhase. This runs at 2400 baud.
The Exidy Sorcerer also uses Manchester encoding. For 1200 baud this
equates to 1 cycle of 1200 Hz for a logic 1, and a half cycle of 600 Hz for
a logic zero. For 300 baud it becomes 8 cycles of 2400 Hz and 4 cycles of
1200 Hz. It sounds like plain FSK, but if you draw the waveform for
"101100" at 1200, you'll see it's actually a Manchester code:
__ _____ __ __ _____
| |__| |__| |__| |_____| |
--1-- --0-- --1-- --1-- --0-- --0--
> There is a standard called Byte format that uses 300 baud
> and the two tones 1200 and 2400.
Byte format is Kansas City format. It was proposed in Byte and formalised
at the KC meeting.
I think the Commodore PET uses modified CUTS. It records each block twice,
which is why it's relatively slow, but also pretty robust.
--
Pete Peter Turnbull
Network Manager
University of York
Received on Tue Dec 17 2002 - 18:35:00 GMT