Display Postscript

Dummy's (or Idiot's, Moron', or Whatever Doesn't Infringe) Guide to Display PostScript...

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NeXT's Open Step operating system did use something called Display PostScript as its display technology. PostScript is a technology developed by Adobe (of Photoshop fame) and is a descriptive language that allows complex graphics to be described using mathematical equations (or descriptions if you like), as opposed to bitmaps or the like.  This lets the images or text to be printed or displayed at the max resolution possible for a given output device, such as allowing high resolution printers to produce very smooth curves and fonts. Most good printers on the market today are Postscript printers, or use a similar technology.

Put another way, PostScript (and similar technologies) describe the shape of fonts and graphics, rather than just giving an index where the dots are.  It like the difference between describing a circle by listing where a set of dots is needed to display it on some particular screen, versas describing the circle with attributes like: make a blue circle half way down the page, lined up on the right side, 1 inch in diameter, and drawn using a line 1/16 inch thick.  Output devices draw the graphics and/or text based on the description and thats unlinks the content from any from any particular devices physical capabilities.

Adobe owns and licenses PostScript for a fee. NeXT had licensed Display PostScript from Adobe and its use of this technology allowed next to offer a very advanced GUI on top of Unix including the abstracted client/display model of X11. In other words you could work on one NeXT machine, responsive GUI and all, from any other NeXT machine on the network (assuming decent network speed).

When Apple acquired NeXT (is is said) Apple decided that the fees for Display PostScript were too high (probably true, a moderate fee for a high end workstation/server system like NeXT was easily absorbed, but adding that fee to a volume OS like OS X would sting a bit . . or maybe Jobs was just ticked at Adobe . . . hard to know). Instead Apple chose to use PDF, also an Adobe technology, and the bases of its display technology. PDF is similar to Display Postscript, except it is free to use, and (so I understand) lacks the remote session capabilities of Display Postscript.  PDF is a subset/superset of PostScript (I have heard it both ways, which means it is an overlapping technology).

Can you say love/hate . . . I knew you could.

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Created 4/19/04
Modifed 5/20/05  - Nvu, content update