[Coco] serial port problem

[Robert Gault]

Mathieu Bouchard wrote:
>
> Hi, I have built an adaptor between a DB9 serial port and a DIN4 serial port,
> and I can send characters both ways at 300 baud and at 2400 baud now, but when I
> try 4800, 9600 or 19200, I get either garbage or nothing.
>
> This is between Terminate 5.0 in MSDOS 6.22 with UART 16550, and a CoCo 3
> running UltimaTerm 4.1.
>
> Any idea on how to fix this ?
>

Well, aside from using Drivewire instead of Terminate (or some other software 
combination) or getting an RS-232 PAK for the Coco, there may be a problem with 
your serial cable.

The Coco port has a limited number of connections so will not send or receive 
some signals needed for higher speed connections. To quote the Coco service 
manual, "It is also possible that devices which use a larger set of RSW-232C 
signals may be used with the Color Computer 3. This would be accomplished by 
connecting unused device inputs to the correct high or low level."
You can do this by bridging cable lines inside either the PC or Coco connectors.

I'm not sure where I got this info but you could try it. I'm sure I have my 
cable set this way.

PC DB9 connector - bridge lines
  DB9 6 to DB9 4
  DB9 7 to DB9 8

Robert