[comp.sys.mac.programmer] Problems with Async LaserWriter Driver 4.0

mathmyka@cosmo.UUCP (Mathias Myka) (01/08/91)

I have recently acquired an Adobe PostScript Cartridge for the
HP LaserJet II. (Please note that there is also a Adobe PS
cartridge from Hewlett-Packard, which only works in the new
LaserJet III).

While this combination works fine in connection
with a PC-compatible computer, I have problems in connecting the
printer to my Macintosh II cx.

The setup I am using is as follows:
- Apple's Asynchronous LaserWriter Driver 4.0
- System 6.0.4
- Cable with TxD, RxD and HskO (to printer DSR/CTS) connected,
  attached to the Mac's modem port
- Printer set to 9600 Baud, 8 databits, no parity,
  1 stop bit

This configuration was successfully tested with a
LaserWriter II NTX (with two stop bits, which is the LW II NTX default),
configured with its 25-pin connector as input. However,
it does not run with the HP LaserJet II.

I _am_ able to talk to the LaserJet II printer through a terminal
emulation program; e.g., PostScript's executive mode works
flawlessly.

The problem seems to be the LaserWriter Driver; the Driver is
obviously able to establish an initial connection to the
printer (commands in the file "Direct.ACL"). After processing
the ACL commands (Exit 0), the driver (quite unneccesarily)
sends the sequence <Ctrl-D> <Ctrl-T> with a very short pause
between the two characters.

Since the LaserJet isn't very fast, it possibly does not
recognize the <Ctrl-T> status request and never sends an
answer. As a result I get the following message on the screen:
"status: connection unsuccessful - LaserWriter not responding".
This situation doesn't change if I lower the baud rate or use
a slower Mac (i.e. Plus).

Observation: After a <Ctrl-D> is sent, it can take up to 6 seconds
until the printer returns to the idle state.

The specific questions I have (other than: "how can I make it
work ?") are:
a) how can the Asynchronous LaserWriter Driver be changed (patched)
   to either make a longer pause between <Ctrl-D> and <Ctrl-T>
   or not send the <Ctrl-D> at all (this is already done in
   the ACL file, and therefore not necessary) ?
b) am I using the latest version of the Asynchronous LW driver; is
   there a newer version that contains a fix for this problem ?
c) are there any third-party PostScript drivers for the Mac that
   allow the connection of PS printers through RS-232 / RS-422 ?

Thanks for any help !

- Mathias Myka
  Memmingen, Federal Republic of Germany
  E-Mail: ...!unido!cosmo!mathmyka (mathmyka@cosmo.UUCP)