Rich Mellor wrote:
On 12/04/2011 22:04, Adrian Ives wrote:
<<CUT>>
2) Yes, input; but the USBWiz can't do split baud rates and it isn't
easy to
do split rates on a standard QL without additional hardware and/or
software.
The input limitation is two stops at 9600. The USBWiz only sends one
so it
doesn't work. Therefore 4800 is the top speed.
Hermes (as well as SuperHermes) cures this to some extent, allowing
different baud rates for ser1 / ser2 input (as well as being different
to the output baud rate).
Hermes also supports just one stop bit at 9600 baud.
The handshaking on serial input is also improved with Hermes, which
would probably overcome the loss of characters you reported on
standard QL hardware.
Minerva provides the ability to have different output baud rates on
ser1 and ser2 also.
Just to explain...
The original 8049 code used a buffer for serial data, with pointers to
the next byte available, the next free space, AND a count of bytes in
the buffer. It updated these three independently, which is insane, and
could end up with them getting out of step with one another. There would
be a byte, or bytes, in the buffer, but the counter said they were not
there. No driver code in the 68K could EVER correct for this.
At the time, various people (myself included) were getting into the
"Bulletin Board" thing - and serial ports that were unusable after 4800
baud just weren't acceptable. Enter Hermes - a rewrite of the 8049 code
from scratch.
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