At 2:03 AM 4/18/97, David Bushong wrote:
>OK, so I got a new Epson Stylus Color 600, which seems (fairly) happy with
>MacOS, but lo and behold I try dumping text to it from NetBSD and I get...
>pages of 'x's.  Upon further inspection (RTF instruction book)  I notice
>it claims that its serial interface is "RS-423"  Now, normal unix serial
>drivers use RS-232, right?  Is there any chance of my faking it?  Do I
>have any chance at all?  Do I have a clue?

RS-232 specifies electrical levels, a 25-pin D connector, and the
functional pinout of that connector.  For the electrical level
specification yoiu can only reliably go to about 20KBaud over any noticable
distance.

RS-422 and RS-423 specify only electrical levels, not connector or pinout.
Both are "upward compatible" with RS-232 in the sence that they specify the
same voltage levels, but 423 adds some pulse-shaping to allow transitions
to travel over longer distances at higher rates than 232.  RS-422 goes
further by specifying differential signalling:  a signal line is a pair of
wires and each wire has the opposite voltage of the other.  This means that
over twisted-pair wires there is no radiated energy loss and you can do
multi-mega-baud rates over reasonable distances if you have good quality
wire (can you say Category 5?).

Anyway the upshot of all this is that what you quote is not a software
issue.  The serial driver should work as far as it goes.  If the printer
works under MacOS then you have already solved all the pinout and voltage
level problems.  Now you need to worry about what data format and protocols
are used by the printer.  The RS- specifications will not help you here,
and you will probably need to write your own filter for the print spooler
to make it work.

Does the Epson manual give you the low-level commands the printer obeys?

Signature failed Preliminary Design Review.
Feasibility of a new signature is currently being evaluated.
h.b.hotz@jpl.nasa.gov, or hbhotz@oxy.edu