On Thu, 11 Nov 1999 svinto@ita.chalmers.se wrote:

> hi all,
> 
> i've recently intalled NetBSD on a Sparc Classic to use as a
> print-server. however, it seems i can't get the serial port to do
> 56700 which is required by the printer, an HP DeskWriter 550c. i get:
> 
> lp: tcsetattr: Invalid argument
> 
> if i put 56700 in /etc/printcap. 38400 works, but of course the
> printer just prints jibberish. 
> 
> the print-server i'm using today is an old Macintosh SE/30 also
> running NetBSD 1.4.1 which works like a charm, only it's a bit slow.
> if i'm not mistaken both these machines use the same serial chips. so
> why can the Mac do 56k but not the Sparc? or am i missing something
> here?

While the two machines use the same serial chip, they DON'T use the same
clock frequency to drive the baud rate generator. The Sun machines
actually use a slightly higer clock rate. The net result is that the
highest two baud rates the mac can support are 57600 and 38400, which for
suns they are 76800 and 51200.

So unfortunatly it won't work.

The only way to get it to work would require:

1) hooking up an external clock input to the Sun and feed it the clock
rate the mac uses

2) modify the sparc zs code to make use of that clock source if it's
available. mac68k and macppc have code which will do this.

Take care,

Bill