LaserWriter
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The Apple LaserWriter was one of the first laser printers available to the mass market. Combined with GUI-based programs like Adobe PageMaker on the Macintosh, it is generally considered to have sparked the Desktop publishing (DTP) revolution in the mid-1980s.
Unlike models from HP, which had been introduced a few months earlier and used their proprietary PCL printing language, the LaserWriter included the PostScript page description language which allowed for far more complex graphics, high-resolution bitmap graphics, outline fonts, and generally much better-looking output.
The use of PostScript comes at a cost. Unlike PCL and other early printer control languages, PostScript is a complete programming language and requires a complete computer to run it. In the case of the LaserWriter this was a Motorola 68000 CPU running at 12MHz, making it the fastest machine in Apple's lineup, and the most expensive at $6,995 when it was introduced in late 1985.
At this sort of price point the printer needed to be shared among several computers. However LANs were both complex and expensive at the time, so in typical Apple fashion they wrote software to drive the Mac's RS-422 port at about 250 kbit/s, wrote a protocol stack called AppleTalk to run on top of it, and delivered the result as LocalTalk (referring to the hardware, cabling and software).
When shared between several machines, the LaserWriter quickly fell to an attractive price point. It was unmatched in terms of printing ability, and could be fully utilized only under a GUI-based computer, on which Apple had the monopoly at the time. Millions were eventually sold, and the LaserWriter is also credited with saving both the Macintosh, and Apple.
Building on the success of the original LaserWriter, Apple developed many successive models. These later LaserWriters offered faster print speeds, higher resolutions, ethernet connectivity, and eventually, color output. To compete, many other laser printer manufacturers introduced models with PostScript capability. Eventually, the standardization on ethernet and PostScript as a means for connecting to and controlling laser printers made Apple's printers superfluous, and Apple discontinued the line after the LaserWriter 8500.
The LaserWriter has an interactive PostScript interpreter: one can actually connect a serial terminal to the printer and, by typing `executive', communicate with the printer's computer. The printer will also display diagnostic error messages on this link. (RS-232, 19.2 kbaud, 8 bit, no parity, 1 stop bit.)it:LaserWriter