[Coco] Eureka! I'm Running My Coco 3 with Drivewire 4 Server Finally! or I Found a Bug in HDBDOS v1.4 DW4 Coco 3!

[Tormod Volden]

On Tue, Sep 17, 2013 at 11:04 PM, Aaron Wolfe wrote:
> IIRC, the sequence is supposed to be sent at 230k, and the server is
> supposed to be at 115.
> The result of this mismatch is static and detectable, and that is what
> the server is looking for.

I am curious to know how that works. The HDB-DOS code simply sends an
$E6 byte at turbo speed. From what I can see the server simply checks
for $E6 as well, but at the slower speed.

Does the below make sense (TTL levels)? For instance can $67 be read
as $FD if I got it right:

^^^^^^^^ _ _^^_ _^^^ ^^ ^^^^^^^^^ (idle, start bit, 6, 7, stop bits,
idle) sent at high speed, MSB first

^^^^ _ ^_^^ ^^^^ ^  (start bit, D, F, stop bit) interpreted at half
speed, LSB first


But hard to make something to look like $E6:

^^^^ _ _^^_ _^^^ ^ ^^^^ (idle, start bit, 6, E, stop bit, idle)
interpreted at half speed, LSB first

^^^^^^^^ _  _ _ _^ ^^^_  _  _ _^^^^^^^^^^^ (idle, start bit, 1 , E,
but then impossible/low stop bit) to be sent at high speed, MSB first


And if we send $E6 at high speed, MSB first:
^^^^^^^^_ ^^^_ _^^_ ^^ ^^^^^^^^
interpreted at low speed the start bit will be too short...

>
> Aye, its an oversight and I will correct it very soon.

Much appreciated!

Tormod