From mboxrd@z Thu Jan 1 00:00:00 1970 MIME-Version: 1.0 In-Reply-To: <3aaafc130908141737k53505228k365717d5a296980@mail.gmail.com> References: <4e6ca2050908140304i1a78ad52i131fdb5a96560f41@mail.gmail.com> <4e6ca2050908140429t4fbba7deieec0ad9dbeb52ae5@mail.gmail.com> <3aaafc130908141737k53505228k365717d5a296980@mail.gmail.com> Date: Fri, 14 Aug 2009 18:06:20 -0700 Message-ID: Subject: Re: [9fans] HP: Printing with the Illiterate From: Russ Cox To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Topicbox-Message-UUID: 4aa0cd78-ead5-11e9-9d60-3106f5b1d025 On Fri, Aug 14, 2009 at 5:37 PM, J.R. Mauro wrote: > IJS is probably it; that's the PCL driver for the home-office class printers. IJS is not PCL. IJS is a custom protocol that is spoken between a bitmap-producing program like Ghostscript and a bitmap-printing program like /usr/bin/hpijs http://svn.ghostscript.com/ghostscript/branches/mtrender/ijs/ijs_spec.pdf /usr/bin/hpijs speaks IJS to Ghostscript (or whatever is on standard input/output) and speaks a new HP protocol called LIDIL to the printer on the other end. Rather than commit to a full specification of LIDIL and have to worry about backwards compatibility in the future, HP chose to use IJS as a shim protocol and distribute a binary that talks to the printer (source is available but it's still a binary). PCL is not in the picture. Getting PCL out of the picture is exactly the reason that IJS and LIDIL were introduced, because LIDIL is basically "here is a bitmap" whereas PCL is a real language that requires actual memory and computing power inside the printer. LIDIL moves the memory and computing requirements out of the printer into the computer proper. Russ