[comp.lang.postscript] HP Laserjet III choking on Laser Prep

phys169@csc.canterbury.ac.nz (05/15/91)

I've had difficulty in getting an HP Laserjet III (with PostScript) to print
postscript files using the Laser Prep from Apple, which includes a string of
characters including "1ab3". Each time it chokes on "1ab3" but such files print
okay on other printers. Can anybody help explain it to me? Is this a known
limitation with the implementation of PostScript on the HPLJ 3? Is there
any easy solution?  (I can supply more information if needed.)

Thanks in advance,
Mark Aitchison, Physics, University of Canterbury, New Zealand.

phys169@csc.canterbury.ac.nz (05/15/91)

In article <1991May15.111938.743@csc.canterbury.ac.nz>, I wrote:
> I've had difficulty in getting an HP Laserjet III (with PostScript) to print
> postscript files using the Laser Prep from Apple, which includes a string of
> characters including "1ab3". 

Thanks for the help. The answer was:

there is a loop doing a read 722 times, for 718 characters of data plus 4 line
terminators (presumably Carriage Returns). The local VAX software is sending
Carriage Return+Line Feed pairs, and the other printer, an NEC, plugged into
the same place must simply be ignoring either the CR or the LF. The extra
one character per line causes headaches for the program, since the last 4
data bytes are interpreted as PS code. 

This is the second time control characters have caused problems for me - a Form
Feed was upsetting a Brother printer, but other PostScript printers simply
ignored it. It seems the response to some common control characters varies from
implementation to implementation (I can't find anything about them either in
the printers' hardware manuals or red & blue PostScript books; perhaps I'm
missing something?).

Morale of Story: beware of control codes, and avoid using "read".

Mark Aitchison, Physics, University of Canterbury, New Zealand.

tj@gpu.utcs.utoronto.ca (Terry Jones) (05/17/91)

>postscript files using the Laser Prep from Apple, which includes a string of
>characters including "1ab3". Each time it chokes on "1ab3" but such files print
>okay on other printers. Can anybody help explain it to me? Is this a known

I think what is happening may be dependant on how you are sending the files
to the printer. I will take a guess that since you are seeing the 1ab3 error
then you might be sending it from a unix host or through some non standard
method. In this case there are times when an original LaserWriter might work
and a newer or different PostScript printer might fail because of some logic
in LaserPrep. There are parts that check if sertain code is built into
the printer, and if so it is supposed to "skip" part of the laserPrep file. 
In non standard communication setups this skip may fail and thus code
that is supposed to be skipped or eexec'ed (not a typo) normally will
be executed as PostScript and choke. 

tj

fritz@csc.ti.com (Fritz Whittington) (05/19/91)

In article <1991May16.205103.21762@gpu.utcs.utoronto.ca> tj@gpu.utcs.utoronto.ca (Terry Jones) writes:
>>postscript files using the Laser Prep from Apple, which includes a string of
>>characters including "1ab3". Each time it chokes on "1ab3" but such files print
>>okay on other printers. Can anybody help explain it to me? Is this a known
I didn't see the original post, but the "1A" is probably the culprit if
you are on an MS-DOS machine.  The DOS "copy" command will stop copying
when it sees a CTRL-Z (1Ah) in the file.  To get around this, use the
"binary" switch (/b) on the copy command:  "copy /b filename.ps prn"
--
Fritz Whittington