Re: EOF characters in XyWrite files

[Dale Schultz dale@xxxxxxxx]

Hi

the contents of the file on disk is almost totally unrelated to what gets sent to the
printer.

say the file contained ABCDEF
representing a document that was to print A though F in one line.

A fictitious printer may need to be sent a stream of bytes like this:

Alpha-1;Alpha-2;Alpha-3;Alpha-4;Alpha-5;Alpha-6;$formfeed

The XyWrite printer driver defines the transformation of A to Alpha-1; and B to
Alpha-2; etc

So when you print the document, the transformation is done and the printer byte
stream is sent to the printer port.

Now imagine the XyWrite file contains:
ABCDEFDocinfo etc.

The stuff that is to be printed is still ABCDEF
The transformation to the print stream is identical

Bottom line is: what is in the file is almost unrelated to what goes to the printer.
I say 'almost' instead of 'completely' only because for any given printer driver
there is a predictable transformation from the file content to the binary byte stream
sent to the printer.

If you want to see what gets sent to the printer for a given document, do this

TYF ,xx
the open the file xx
what will most likely look like garbage is the binary data that would have been sent
to the printer if XyWrite had not sent it to the disk file called xx. print control
syntax typically includes many escape characters which display in XyWrite as
triangles.

Note that the binary steam that goes to the printer can contain byte number 26 (which
is sometimes interpreted as an end of file marker) - that is perfectly legal and may
even be demanded as part of the print control syntax.

Now at the risk of confusion... if you open that xx print file in XyWrite it will
likely only show you the contents up until the first byte that has the value 26!

I seem to recall that there was also a command CAB that means "CAll Binary" which
will open the file based on the directory file size, and hence include any embedded
EOF characters..

Dale
http://dale.mixmox.com








----- Original Message -----
From: "Michael Norman" 
To: ; 
Sent: Tuesday, October 17, 2006 8:02 PM
Subject: Re: EOF characters in XyWrite files


> At 01:44 PM 10/17/2006, Dale Schultz wrote:
>
> >So binary files can have as many EOF characters as one likes. Each
> >byte of the file
> >is simply a value between 0 and 255 and 26 can be treated just like any other.
>
> Thanks for the precis, Dale. Question is: if a file has more than one
> EOF character, how, if at all, is a printer affected? A lot of
> variables: the machine itself, printer language its using, XY printer
> file and so on. In my case it may have affected only one of XY's many
> printer command alternatives. On the other had, as Patrica suggests,
> I might have just bumped the printer during the print run, jarred a
> cable lose and that was the problem.
>
> Michael Norman
>