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[Yvan]

Symptoms
When printing from a Macintosh to a printer using any non-Appletalk method such as LPR/LPD, IPP, Rendezvous, USB, etc., certain files will result in many "garbage" pages being printed, each one usually having a line or several lines of random characters.

This behaviour is present on many printers including many made by Hewlett-Packard (HP). Similar behaviour occurs if the users prints via a print server such as a Windows print queue that ultimately ends up printing the file using one of the IP methods.

Cause
The Postscript code that is being sent to the printer contains binary data that is incorrectly formatted and is unexpected to these printers.

Contrary to many articles on the internet, the problem is not because these printers cannot handle binary-encoded postscript but rather an assumption the printer makes about the data based on the type of connection established by the client machine.

The purpose of binary encoding postscript is to reduce the size of the resulting postscript file and/or increase the speed at which the Postscript interpreter is able to process the file. Binary encoding is supported in Postscript levels 2 and 3. There are two ways postscript can be binary encoded, "Postscript Binary" and "Tagged Binary Core Protocol", or TBCP. Some people will refer to Postscript Binary as "standard format". This is incorrect and misleading, as Adobe defines Standard Protocol as a text-only serial protocol.

Printers affected by this problem assume that binary data received over Appletalk connections is encoded in Postscript Binary and assume that binary data received over non-Appletalk (IP) connections are encoded using TCBP. This is an incorrect but fair assumption that results in the printing of garbage.

The Macs should not be sending Postscript in this format because:
(a) Postscript Binary was superceded by TBCP