[Coco] Max baud rate for 68681 in MM/1?

Joel Ewy jcewy at swbell.net
Mon Feb 1 21:35:33 EST 2016

On 02/01/2016 12:13 AM, Dave Philipsen wrote:
> That implies a maximum data rate of 230,400 bps but I'm not so sure 
> the 1488/89 chips would go that fast.  They were the de facto chips of 
> choice for RS232 back then but, as you say, most people never 
> attempted anything much faster than 38,400.  Maybe someone can recall 
> the practical limit on those drivers/receivers.
> There's a strong possibility that you could replace the crystal with a 
> 7.3728 MHz crystal, replace the Signetics with Exar, and split out the 
> TTL signals and connect them to a more modern RS232 transceiver and 
> you'd be in business at least up to 460,800 bps.
Drivewire feels pretty comfortable on the CoCo at 115K, so that should 
be adequate.



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