External clocking a serial port?

Giuliano Pochini pochini at denise.shiny.it
Tue Apr 11 10:51:41 EST 2000

DeRobertis wrote:
> To run a Mac serial port at 1.8Mbps like the Epson Stylus Color 740's
> docs say it can, you need external clocking.
> I'm guessing the Stylus Color 740 is sending out the proper clock to do
> so -- and no doubt that would take out Linux using the crtscts option !

Hmm, It's possible...

> The clock input and remote side ready just happen to occupy the same
> pin. That would explain it flapping the ready so many times per second.
> How do I turn on external clocking under linux?

You have to hack the driver:


#define EXTSYNC         0x30    /* External Sync Mode */


/* Write Register 11 (Clock Mode control) */


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