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SX Parts Catalog

Printers and Controllers
Hewlett-Packard Printers

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HP LaserJet III Printer

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Model Information

Model Number               HP 33447

Model Number               HP 33449

Introduction Date          March 1990

Original MSRP              $2,395

Replaces Model             LaserJet series II

Replaced by Model          LaserJet 4


The Resolution Enhancement Technology (RET) introduced with the HP LaserJet III represents a technical milestone in the history of desktop laser printers. RET eliminates the fine stair steps normally seen on diagonal lines from printers with conventional 300 dpi controllers. RET uses variable dot sizes to smooth jagged lines and edges on all types of text and graphics. It also sharpens corners and intersections by placing smaller dots at the pointed tips. The result is print quality that has the sharpness of 600 dpi on the edges.

The LaserJet III also introduced the PCL 5 printing language with enhanced page formatting features. PCL 5 is a superset of PCL 4, which is built into other LaserJets. It provides the LaserJet III with much of the functionality of PostScript without the cost and processor overhead. All older PCL 4 applications should print perfectly with PCL 5. HP also integrated its industry standard HP-GL/2 pen plotter language into PCL 5. HP-GL/2 allows graphics to be described very efficiently and many CAD applications require it. Older LaserJet II printers required PDP's Plotter-in-a-Cartridge product to emulate HP-GL/2.

PCL 5 was conceived as a substitute for PostScript much in the same way Canon developed CaPSL. A major shortcoming of CaPSL is that it's a dead-end for higher print quality; there are no typesetters that use CaPSL. Most publishers using PostScript use low-cost 300-dpi laser output for drafts and then print to PostScript-equipped image setters, such as a Linotronic machine, for the final film.

This exact correspondence between low cost proof copies and typeset-quality camera-ready copies has been one of the key ingredients for the phenomenal success of PostScript and its creator, Adobe Systems, Inc. HP realized that in order for PCL 5 to be a substitute for PostScript, there had to be high resolution typesetting equipment compatible with PCL 5. So HP teamed up with CompuGraphic to use CG's Intellifont type fonts and scaling technology as part of PCL 5. Together they wrote a program called DirectSet that translates PCL 5 commands into code for the AGFA Compugraphic Series 9000 imagesetters.

To hedge its bets, HP also contracted with Adobe to provide a PostScript cartridge for the LaserJet III. Resolution Enhancement Technology works well in the PostScript mode, but you should disable RET when printing scanned images because the dots added by the RET circuitry to smooth the image tend to reduce clarity. The LaserJet III allows the operator to turn off RET from the control panel. The LaserJet III sold far better than expected and was in short supply during all of 1990. The III was HP's third grand slam in the printer business and is one of the most popular printers on the market.

On October 26, 1992 Hewlett Packard bombed the laser printer industry with the much anticipated introduction of the LaserJet 4 and LaserJet 4M. These reasonably low-cost 8 ppm printers are based on the new Canon P-270 engine (also called EX), which provides true 600 dpi by way of new ultra-fine toner technology. EX printers are smaller than the SX/TX, with both a 75 sheet multipurpose tray and a 250 sheet cassette as standard and a third cassette (500 sheet) as optional. Hewlett-Packard killed the LaserJet III and critically wounded every other OEM of the SX engine. It was a sad, but inevitable, day for the SX engine. Four months later, in February 1993, Canon sent letters to all SX OEMs announcing the last chance to place orders for SX and TX engines as production would end by 1994. The RX engine remained in production until a duplex printing option was created for the revised LaserJet 4, called the LaserJet 4 Plus.


PCL 5 works with scalable fonts and the LaserJet III includes 8 scalable typefaces (the CG Times and Univers families). CG Times is like Times-Roman, and Univers is very much like Helvetica. These two faces are provided in normal, bold, italic, and bold italic. Type can be scaled in quarter-point increments from .25 up to 999.75 points. Bitmapped Courier and line printer fonts are also included, as are 35 internal symbol sets. See the HP Font Cartridges page for more information.


The HP LaserJet III has been discontinued, but The Printer Works can build them from parts at special request. Refurbished printers are in like-new condition and come with a full-one-year warranty. For a price quote, select the printer's part number in the ordering information table.

Controller Notes

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Part Number                10 MHz: 33449-60001
                           10 MHz: 33451-60001
                           16 MHz: 33497-60001

Designer/Mfg.              HP

Design Similar to          None

Std. Emulations            PCL 5 (incorporates HP-GL/2)

Opt. Emulations            Adobe PostScript

Emulation Brand            HP

CPU & Clock Rate           68000 @ 10 MHz or 16 MHz

ASIC(s)                    Yes, HP Proprietary 1MK6-0201

Bitmap Resolution (max)    300 X 300

RET                        Yes

Base RAM                   1 Megabyte

Max RAM                    5 Megabytes

Font Cartridges            2 Slots, Std. Full Size

Control Panel Type         Full Function with 16 Char. LCD

Standard Interfaces        RS-232, Centronics Parallel

Optional Interfaces        AppleTalk, External Video, LAN

Like the IID controller, the LaserJet III controller was designed and built by HP rather than Canon. The boards are made in the U.S.A. (Boise, Idaho) and then sent to Japan for integration into the printers. Three major revisions of the circuit board exist. The part numbers are: 33449-60001, 33451-60001, 33497-60001. HP uses the suffix 69001 instead of 60001 to label boards that have been "restored" by their repair facility and sold as replacement parts.

The early revision boards used many small surface-mount chips and five large 40-pin masked ROMs for the firmware. The new boards have all the functions of the small chips integrated into a few large Application Specific Integrated Circuits (ASICs), and the firmware is placed in four small surface-mount masked ROMs. A picture of the original version HP III controller is shown above. The latest version, with its large ASICs, is shown in the next section, covering the LaserJet IIID.

HP's investment in custom surface-mount chips allows it to produce high-quality controllers that are extremely reliable at a fraction of the cost of the original LaserJet and LaserJet II controllers. HP engineers have created the highest ratio of controller performance to build cost in the industry. This technological edge allows HP to sell printers at competitive prices and still enjoy a healthy profit margin.

The controller contains an ASIC for RET. This special chip scans multiple raster lines and generates different sized dots to eliminate the "jaggies" on diagonals and curves, sharpen the tips of points, and clean up the inside corners of line intersections. All this results in better looking print which, at its best, can approach the output of 600 dpi controllers.

One of the beauties of RET is that it improves print quality without increasing RAM requirements or degrading print speed. Since PCL is basically a 300 dpi protocol, it was important for HP to figure out a way to improve print quality without losing compatibility with 300-dpi font and graphic data. Another advantage is that RET acts independently of the controller's native language, yielding enhanced output whether the original bitmap was created by PCL 5, PostScript, or any other process.

Another nice feature of the LaserJet III controller design is that it can plug into a LaserJet II and effectively turn the older printer into a LaserJet III. This upgrade can be made without changing anything else, since the mechanical design is identical. Although the control panels look different, they are functionally identical. It's a pleasant surprise to see a faithful old LaserJet Series II produce beautiful resolution-enhanced output after a new LaserJet III controller board has been installed!

Standard memory is 1 megabyte and two slots are provided to add up to 4 additional megabytes. HP was criticized for providing non-expandable memory boards for the LaserJet II and IID. Memory cards from HP are still not expandable, but HP included a second slot in the III so that you don't have to discard your old card when you add memory to a printer that already has a card installed. HP does not make a 4 megabyte memory card for the LaserJet III.

The optional video interface does not work with products such as the JetScript Adapter, but it works fine with interface cards that merely use the video lines (e.g., the LaserMaster). The LaserJet III uses the same RAM cards as the IID and the IIP, but it has two slots instead of one. These cards are different from those used with the Series II.

LaserJet III and IIID Use the Same Controllers

All versions of the LaserJet III controller will function perfectly as either a LaserJet III or a LaserJet IIID controller! HP shrewdly programmed the LaserJet III controller to sense the engine type and operate accordingly. As a result, service facilities need only stock one type of controller to support both LaserJet III and IIID printers.

Supplies and Accessories

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You can check prices or order these items from the ordering information table below.


The HP LaserJet III uses the same toner cartridges as all other SX-based printers.


There are many font cartidges made by HP for the HP LaserJet family. When you want to increase your printer font collection, see our catalog page on Font Cartridges from Hewlett-Packard.


The LaserJet IID printer uses the same shaped paper trays and high-capacity feeders as all other SX-based printers. All versions are physically interchangeable, but there are slight color differences. (See also Diagram 300.)

You can also buy third party high-capacity feeders for paper or envelopes, as well as an output stacker, to add productivity to SX, RX and TX printers. The sheet feeders can hold up to 1500 sheets; the envelope feeder up to 250 envelopes. The stacker extends your printer's output hopper, allowing it to stack up to 500 sheets.


The HP LaserJet III has two RAM expansion slots. The 1 MB and 2 MB RAM cards available from HP can be added in combinations to give you 1, 2, 3, or 4 MB of additional memory. The generic RAM cards are available unpopulated (0 MB) or filled with 1, 2, 3, or 4 MB. These cards can be used only in a single slot, you cannot combine these with a RAM card in the second expansion slot.


Although slow compared to high end controllers, the LaserJet III controller is one of the best available for SX engines, offering excellent print quality as well as broad compatibility. For PostScript compatibility, we recommend one of the PostScript Emulation cartridges from HP.

Ordering Information

Model Information | Controller Notes | Supplies and Accessories
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For price and ordering information or to place the item in your shopping cart, select a Part Number in the table.

Part Number                  Description

33449A                       Printer, HP LaserJet III, 110/115 50/60Hz

33449AB-AU                   Printer, HP LaserJet III, 220/240V 50Hz

Part Number                  Description

33449-60001                  Controller, HP LaserJet III/IIID (10 MHz)

33449-60001-AEX              Adv. Exch., Controller, HP LaserJet III/IIID (10 MHz)

33451-60001                  Controller, HP LaserJet III/IIID (10 MHz)

33451-60001-AEX              Adv. Exch., Controller, HP LaserJet III/IIID (10 MHz)

33497-60001                  Controller, HP LaserJet III/IIID (16 MHz)

33497-60001-AEX              Adv. Exch., Controller, HP LaserJet III/IIID (16 MHz)

Part Number                  Description

33474B                       Memory Card, 1MB for HP LaserJet IIP/III/IIID/IIIP

33475B                       Memory Card, 2MB for HP LaserJet IIP/III/IIID/IIIP

33474B-CLN                   Memory Card, 1MB, Generic for HP LJ IIP/III/IIID/IIIP

33475B-CLN                   Memory Card, 2MB, Generic for HP LJ IIP/III/IIID/IIIP

33477B-CLN                   Memory Card, 4MB, Generic for HP LJ IIP/III/IIID/IIIP

Part Number                  Description

33416A                       AppleTalk Interface Kit (Requires 33439P and Memory)

33439P                       Adobe PostScript Emulation and Font Cartridge

Part Number                  Description

92297B                       Paper Cassette, Letter, HP III/IIID

92297C                       Paper Cassette, Legal, HP III/IIID

92297D                       Paper Cassette, A4, HP III/IIID

92297E                       Paper Cassette, Executive, HP III/IIID

92297F                       Envelope Cassette with Top, HP III/IIID

Part Number                  Description

LCS-SX-USP                   Feeder, Sheet, Genesis JetTray 1500 for SX

LCSEF25-SX                   Feeder, Envelope, Genesis JetTray 250E for SX

MAINTENANCE KIT --->Contents of Kit (See photograph and details.)
Part Number                  Description

33449-37904                  HP LJ 2/2D /3&347: 3D Maintenance Kit, 120V, 100K Pg. Rpl. Parts

Part Number                  Description

33449-90901                  HP III, User's Manual

33481-90969                  HP III, PCL5 Technical Reference Guide

33449-90905                  HP III, Setup Guide

33449-90906                  HP III & HP II Combined, Service Manual

Each SX maintenance kit contains (see photograph and details):

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