[comp.sys.mac.system] DeskWriter & System 7.0

pino@cory.Berkeley.EDU (Jose L. Pino) (05/23/91)

I just learned from HP that the current deskwriter printer driver (2.1)
does not support virtual memory.  A new driver is in the works but they
didn't know when it would be finished.  So, to print on the deskwriter
in system 7.0 turn VM OFF!!

Jose Pino
pino@cory.berkeley.edu

neff@hp-vcd.HP.COM (Dave Neff) (05/24/91)

>I just learned from HP that the current deskwriter printer driver (2.1)
>does not support virtual memory.  A new driver is in the works but they
>didn't know when it would be finished.  So, to print on the deskwriter
>in system 7.0 turn VM OFF!!
>
>Jose Pino
>pino@cory.berkeley.edu

Just a couple of comments.  The problem is only with the serial version
of the driver.  The AppleTalk version works fine.  The problem is really
due to the Mac O.S. not noticing the fact that DTR is de-asserted and
insisting on sending many K of data.  Although it really seems to be
a Mac O.S. bug, there may be a work around in the driver but it may affect
the printer driver performance when VM is turned on.  I really hope
Apple fixes this, but who knows.  I kind of doubt supporting the DeskWriter
is high on their list of things to do :-).  Evidentally it is only
a problem for devices using 57.6K baud, and few devices other than
the DeskWriter use this baud rate.  I have also read on the net that
XON/XOFF handshaking also doesn't work very well at 57.6 K baud
in pre-system 7 versions (the DeskWriter only uses DTR).

The finder icon glitch is also a known problem.  Actually, the
messed up icons are kind of cute on my 8 bit monitor :-).  Definately
an HP driver bug that is being fixed.

So either turn VM off or use AppleTalk for now.  We have had a variety of
problems with certain hardware (accelerators, third part VM support,
even the Mac portable) causing the Mac to not (or very slowly) notice when
we drop DTR.  In AppleTalk mode this is not a problem of course.  And
since I wrote allot of the AppleTalk firmware I know it works flawlessly :-).

Sorry, I can't give any dates on when a new driver will be out.
I don't know the schedules and HP in general hates to give out dates on
anything futures related.  I do printer firmware not printer drivers so
I really don't even know the release schedule.

Dave Neff
neff@hpvcfs1.HP.COM