Adobe’s approach left a gap in the market which Hewlett-Packard strove to fill with its own device independent-ish page description language based on its Printer Command Language, PCL, which first appeared in the 1970s.
HP’s marketing has been entirely different to Adobe’s, opting for the mass cloners rather than exclusive licensing. This strategy has resulted in a plethora of printers equipped with clones of PCL costing much less than their PostScript-licensed counterparts. The problem with having so many PCL clones around is that it’s not possible to guarantee 100% identical output on all printers. This is only a problem when the intention is to use high-resolution bureaux and where an exact proof is required before sending them the document files. Only PostScript can offer an absolute guarantee.
PCL was originally made for use with dot-matrix printers and is an escape code rather than a complete PDL. Its first widespread incarnation, version 3, only supported simple printing tasks. PCL 4 added better support for graphics and is still used in personal printers. It requires less processing power than PCL 5, or the latest version PCL 6.
PCL 5, developed for the LaserJet III, offered a similar feature set to PostScript, with scaleable fonts through the Intellifont system and vector descriptions giving WYSIWYG on the desktop. PCL 5 also utilised various forms of compression which speeded up printing times considerably compared to PostScript Level 1. PCL 5e brought bi-directional communication for status reporting, but no extra print quality enhancements, while PCL 5c added specific improvements for colour printers.
In 1996 HP announced PCL 6. First implemented on the LaserJet 5, 5N and 5M workgroup printers, PCL 6 is a complete rewrite. It’s a flexible, object-orientated control language, tuned for fast processing of graphically-rich documents and offers better WYSIWYG facilities. This makes it ideal for handling Web pages. The more efficient code, combined with faster processors and dedicated hardware acceleration of the LaserJet 5 printers, results in time-to-first-page speed increases of up to 32% over the LaserJet 4(M)+ printers they replaced.