[rescue] looking for a Multia

Dave McGuire mcguire at neurotica.com
Tue Aug 12 10:09:22 CDT 2003

On Tuesday, August 12, 2003, at 10:18 AM, Sandwich Maker wrote:
> "I was going to use a classic for that task, but now am working on
> "setting up a U1 instead.  Why a U1 for such a light task?  Faster 
> serial
> "ports.
> ummm, excuse me, but afaik the u1 and u2 have the same 8530 zscc
> serial chip as the older suns going back at least as far as the 3/80.
> maximum speed on any of them is 76800, and while i'll grant the u1 has
> more cpu hp to handle the interrupt load, that's the speed i run my
> sparc2 serial port at.

   The Z8530's two ports are good to to 1Mbps.  The problem is the 
frequency of the clock input fed into the chip.  The on-chip 
programmable dividers divide that frequency down to generate the baud 
rates...but if the main clock input isn't high enough, you won't get 
high baud rates out of the dividers.

   Is the U1's Z8530 fed a higher frequency than the older Suns?


Dave McGuire                 "You don't have Vaseline in Canada?"
St. Petersburg, FL                     -Bill Bradford

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