HP LaserJet III (1990)

What the HP LaserJet III was

The HP LaserJet III was a desktop laser printer introduced by Hewlett-Packard in March 1990 at a launch price of US$2,395, according to Wikipedia's HP LaserJet history and the HP Computer Museum. It sat in HP's desktop LaserJet line following the LaserJet II, with which it shared the same eight-pages-per-minute Canon SX print engine noted by the HP Computer Museum. Its two headline additions over the earlier model were Resolution Enhancement technology and HP PCL 5. This page records only facts traceable to authoritative sources; specifications such as standard memory, interfaces, dimensions, weight and any discontinuation date could not be confirmed for the base model and are omitted rather than estimated.

Resolution Enhancement technology (REt)

Resolution Enhancement technology (REt, also written RET) was one of the LaserJet III's two marquee features. The printer remained a 300-dpi device, but, as the HP Computer Museum describes it, REt allowed the laser to adjust the size and position of dots within a character-cell matrix and along the edges of lines and arcs, giving an 'effective resolution of near 600 dots per inch' without added memory or slower printing. The museum notes an important limitation: this smoothing did not apply to bit-mapped (scanned) images, only to text and line art.

PCL 5 and scalable fonts

The LaserJet III was the launch platform for HP PCL 5. As Wikipedia's Printer Command Language history records, 'PCL 5 was released on the HP LaserJet III in March 1990, adding Intellifont font scaling (developed by Compugraphic, now part of Agfa), outline fonts and HP-GL/2 (vector) graphics.' Intellifont let the printer scale outline typefaces to arbitrary point sizes, moving users beyond the fixed 10- and 12-point bitmap fonts of earlier models. The HP Computer Museum lists CG Times and Univers among the internal scalable typefaces built into the machine, and HP-GL/2 added a vector graphics language to PCL for line-art output.

Print method and the Canon SX engine

Like other laser printers, the LaserJet III formed each page electrophotographically: a laser scanner unit swept a modulated beam across a rotating photoconductor drum, the resulting latent image was developed with toner and then fused to the paper. The HP Computer Museum identifies the print engine as a Canon SX engine rated at eight pages per minute, the same engine used in the LaserJet II. Incoming jobs were described in PCL and rasterized to the dot pattern the laser writes, a task handled by a raster image processor. PostScript was not built into the base model; Wikipedia notes that on models before the LaserJet IIISi, PostScript was provided through a font-cartridge solution rather than onboard.

The LaserJet III family

HP shipped variants alongside the base LaserJet III. Wikipedia records the LaserJet IIID as 'the same as the LaserJet III except it had 2 paper trays and duplex printing,' which it lists at US$4,995 in the fall of 1990; the HP Computer Museum corroborates the dual-tray, standard-duplex configuration and dates the IIID (product number 33459A) to 1990, though it records a lower original price of US$3,595. The LaserJet IIISi followed at US$5,495 - a price given by both Wikipedia and the HP Computer Museum - and is described by Wikipedia as 'the first mass-market Ethernet network printer.' The museum documents the IIISi's Canon NX engine running at up to 17 pages per minute at 300-dpi output, with memory expandable from 1 MB to 16 MB and optional duplex printing; Wikipedia adds a 5 MB memory configuration, Image REt, job stacking and onboard Adobe PostScript emulation in place of the font-cartridge approach used on earlier models, and dates the IIISi to March 1991 (the museum lists 1990).

Place in printing history

The LaserJet III is remembered chiefly for the two technologies it introduced. Resolution Enhancement technology raised the apparent quality of 300-dpi laser output at a time before affordable 600-dpi engines; the HP Computer Museum characterises REt as 'the last major improvement in text print quality.' PCL 5, meanwhile, brought scalable outline fonts and a vector graphics language into HP's mainstream office printer, narrowing the typographic gap with PostScript devices such as the Apple LaserWriter while keeping the lower cost of the LaserJet line. Both features carried forward into later LaserJet generations.