Hacking the DECmate serial port

Tony Duell ard at p850ug1.demon.co.uk
Fri Apr 29 17:19:49 CDT 2005


> 
> On 4/29/05, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
> > Not necesarily. The 6402 takes external transmit and receive clocks, at
> > 16 times the desirted baud rate. If the clock generator hardware can't go
> > faster than 16*4800 for some reason, then you won't get more than 4800
> > baud. This is probalby very easy to modify, though.
> 
> Sorry to sound simplistic, but does that mean if I just whack in an
> appropriate crystal, then I'd magically get 9600? (haven't downloaded
> the prints yet)

I've not looekd at the prints, but I'd be wary of changing a crystal. It 
may well be used for the CPU clock, or video timing, or something like 
that. 

I'd try to figure out the divider chain, and see if you can connect the 
UART clock pins to something twice as fast (i.e. one binary division 
stage less). 

-tony



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