5. Supported Printers

Postscript arrived as part of the Apple Laserwriter, a perfect companion to the Macintosh, the system largely responsible for the desktop publishing revolution of the 80s.

Postscript programs can be run to generate output on a pixel screen, a vector screen, a fax machine, or almost any sort of printer mechanism, without the original program needing to be changed. Postscript output will look the same on any Postscript device, at least within the limits of the device's capabilities. Before the creation of PDF, people exchanged complex documents online as Postscript files. The only reason this standard didn't "stick" was because Windows machines didn't usually include a Postscript previewer, so Adobe specified hyperlinks and compression for Postscript, called the result PDF, distributed previewers for it, and invented a market for their "distiller" tools (the functionality of which is also provided by ghostscript's ps2pdf and pdf2ps programs).

Postscript is a complete programming language; you can write software to do most anything in it. This is mostly useful for defining subroutines at the start of your program to reproduce complex things over and over throughout your document, like a logo or a big "DRAFT" in the background. But there's no reason you couldn't compute π in a Postscript program.

Postscript is fully specified in a publically available series of books (which you can find at any good bookstore). Although Adobe invented it and provides the dominant commercial implementation, other vendors like Aladdin produce independently coded implementations as well.

You get what you pay for. Most printers under $200-300 will print reasonably well, but printing costs a lot per page. For some printers, it only takes one or two cartridges to add up to the cost of a new printer! Similarly, the cheapest printers won't last very long. The least expensive printers, for example, have a MTBF of about three months; obviously these are poorly suited for heavy use.

Inkjet printheads will clog irreparably over time, so the ability to replace the head somehow is a feature. Inkjet printheads are expensive, with integrated head/ink cartridges costing ten times (!) what ink-only cartridges go for, so the ability to replace the head only when needed is a feature. Epson Styluses tend to have fixed heads, and HP DeskJets tend to have heads integrated into the cartridges. Canons have three-part cartridges with independently replaceable ink tanks; I like this design. OTOH, the HP cartridges aren't enormously more expensive, and HP makes a better overall line; Canon is often the third choice from the print quality standpoint; and Epson Styluses are the best supported under Linux at the moment. You just can't win.

Laser printers consume a drum and toner, plus a little toner wiping bar. The cheapest designs include toner and drum together in a big cartridge; these designs cost the most to run. The best designs for large volume take plain toner powder or at least separate toner cartridges and drums.

The best color photograph output is from continuous tone printers which use a silver halide plus lasers approach to produce—surprise!—actual photographs. Since these printers cost tens of thousands to buy, Ofoto.com offers inexpensive print-by-print jobs. The results are stunning; even the best inkjets don't compare.

The best affordable photo prints come from the dye-sublimation devices like some members of the Alps series (thermal transfer of dry ink or dye sublimation). Unfortunately they have poor Linux support (the one report I have speaks of banding and grainy pictures), and even then it's unclear if the dye-sub option is supported.

The more common photo-specialized inkjets usually feature 6 color CMYKcm printing or even a 7 color CMYKcmy process. All photo-specialized printers are expensive to run; either you always run out of blue and have to replace the whole cartridge, or the individual color refills for your high-end photo printer cost an arm and a leg. Special papers cost a bundle, too; you can expect top-quality photo inkjet output to run over a US dollar per page. See also the section on printing photographs later in this document, and the sections on color tuning (such as it is) in Ghostscript.

Speed is proportional to processing power, bandwidth, and generally printer cost. The fastest printers will be networked Postscript printers with powerful internal processors. Consumer-grade printers will depend partly on Ghostscript's rendering speed, which you can affect by having a reasonably well-powered machine; full pages of color, in particular, can consume large amounts of host memory. As long as you actually have that memory, things should work out fine.

If you want to print on multicopy forms, then you need an impact printer; many companies still make dot matrix printers, most of which emulate traditional Epson models and thus work fine.

There are two supported lines of label printer; look for the Dymo-Costar and the Seiko SLP models. Other models may or may not work. Avery also makes various sizes of stick-on labels in 8.5x11 format that you can run through a regular printer.

Big drafting formats are usually supported these days by monster inkjets; HP is a popular choice. Mid-sized (11x17) inkjets are also commonly used for smaller prints. Much plotting of this sort is done with the languages RTL, HP-GL, and HP-GL/2, all of which are simple HP proprietary vector languages usually generated directly by application software.