PCL (Printer Command Language)

History

PCL originated in the mid-1980s alongside Hewlett-Packard's early inkjet and laser printers and evolved over roughly a decade of successive printer generations. It is a family of languages rather than a single fixed specification, and the exact dates below are drawn largely from secondary reference sources; where HP's own historical documentation was not directly verifiable, milestones are described as reported.

• PCL 1 / 1+ appeared on early HP inkjet units — PCL 1 on the HP ThinkJet and PCL 1+ on the HP QuietJet — providing basic text and graphics output.
• PCL 2 added electronic-data-processing / transaction-oriented functionality aimed at multi-user system printing.
• PCL 3 is associated with the original HP LaserJet and added bitmap-font support and raster resolution up to 300 dpi.
• PCL 4 was introduced on the HP LaserJet Plus, adding macros and larger bitmapped fonts and graphics.
• PCL 5 was released on the HP LaserJet III (reported March 1990), adding HP's Intellifont scalable/outline fonts and HP-GL/2 vector graphics.
• PCL 5e (HP LaserJet 4, reported October 1992) added bi-directional printer-to-PC communication and improved handling of Windows fonts.
• PCL 5c added color, associated with the HP PaintJet 300XL and HP Color LaserJet products.
• PCL 6 was introduced around 1995 (associated with the HP LaserJet 5 generation) and split PCL into an object-oriented "Enhanced" language (PCL XL) plus a "Standard" PCL 5-compatible mode.

HP also introduced PJL (Printer Job Language) in the early 1990s (reported on the HP LaserJet IIIsi) as a companion, job-level control layer wrapping PCL and PostScript jobs.

What problem it solved

Early printers were driven by ad-hoc, vendor- and model-specific control codes, making it difficult for applications to produce consistent output across devices. PCL provided a relatively compact, consistent command vocabulary that applications and drivers could target, letting a host describe pages — text placement, fonts, line spacing, simple graphics, number of copies, paper size and orientation — without micromanaging the print engine.

As printers gained resolution, scalable fonts, vector graphics, and color, the layered PCL levels allowed new capabilities to be added while older command streams still worked. PCL 6 Enhanced further addressed performance and fidelity for graphical-interface printing: a compact binary, object-oriented stream that could more directly represent the drawing operations of graphical operating systems, reducing translation overhead and data size.

How it works

Classic PCL (levels 1 through 5) is a stream of printable data interleaved with escape sequences. Every command begins with the escape character, written here as Ec (ASCII decimal 27 / hex 1B).

• Two-character (simple) sequences are Ec plus one character. For example, EcE resets the printer.
• Parameterized sequences follow a structured pattern: the escape character, a parameterized/group indicator character, a numeric value field (shown as #), and a terminating character. Examples include:
• Ec&l#X — number of copies (e.g. Ec&l14X for 14 copies)
• Ec&l2A — Letter page size; Ec&l26A — A4
• Ec&l0O — portrait orientation; Ec&l1O — landscape
• Ec(s#H — set font pitch in characters per inch (e.g. Ec(s10H for 10 cpi)
• Related parameterized sequences that share the same leading characters can be combined into one longer sequence, which reduces overhead.

PCL 6 Enhanced (PCL XL) works differently. Instead of text-like escape sequences it is a binary, stack-based, object-oriented stream of operators and their attributes (data values). The stream expresses higher-level drawing objects, and reference sources describe it as "similar to PostScript" in flavor, restricted to binary encoding, and designed to match the drawing model of the graphical interface (Windows GDI).

Where it sits in the print/document pipeline

PCL is a page-description / device language near the end of the printing pipeline:

1. An application renders a document. 2. The operating system's graphics layer and a printer driver translate that rendering into a printer language. 3. For PCL, the driver emits a PCL data stream, often wrapped with PJL job-control commands and, in PCL 5, possibly embedding HP-GL/2 for vector graphics. 4. The printer's firmware interpreter parses the stream and rasterizes it for the print engine.

So PCL sits between the host printer driver and the printer's raster/marking engine. PJL sits around the PCL (or PostScript) job, handling language switching, job separation, and status readback.

Relationship to printers

PCL is tightly bound to HP's printer history and especially the HP LaserJet line: successive PCL levels were introduced on specific LaserJet, DeskJet, and inkjet models, and each level's feature set tracked the capabilities of the engine it shipped on — resolution, scalable fonts, vector graphics, color, and graphical-interface-optimized printing.

Because HP published PCL technical references and PCL became widespread, many non-HP printers implement PCL or PCL-compatible interpreters so they can accept the same data streams. PCL 6 Standard mode preserves compatibility with the large installed base of PCL 5 output.

Relationship to operating systems

PCL is normally reached through a printer driver rather than directly by applications. On Windows, PCL — especially PCL 6 Enhanced — was designed to align with the OS graphics model: its object-oriented commands were intended to match Windows GDI drawing operations, which helps a Windows driver emit PCL efficiently.

On Unix, Linux, and macOS, the common path is CUPS with drivers and filters that can generate PCL for PCL-capable printers. In all cases the OS and driver layer convert the system's rendering into the PCL stream the printer expects.

Relationship to PDF / PostScript / drivers

Versus PostScript: Both are printer/page languages of the laser era. PostScript is a full, Turing-complete programming language with rich, general graphics and typographic control and supports both plain-text and binary encodings. Classic PCL (1 through 5) is a more compact command/escape-sequence language, historically lighter-weight to interpret. PCL 6 Enhanced is stack-based and object-oriented — described in sources as similar to PostScript in flavor — but is restricted to binary encoding and is oriented toward matching graphical-interface drawing rather than being a general programming language. Historically PostScript was common in graphic-arts and desktop-publishing workflows while PCL was widely used for general office printing; many printers offer both.

Versus PDF: PDF (standardized as ISO 32000) is a document interchange and archival format — a fixed page representation for viewing and exchange — not a printer command stream. PCL is a device-facing print language. Modern workflows often start from PDF, which a driver or RIP then converts into PCL (or PostScript) for a given printer.

Drivers: In practice the driver is what produces PCL. HP historically shipped universal print driver packages offering PCL 5, PCL 6, and PostScript emulation options, and many third-party printers include PCL emulation so standard PCL drivers work.

Modern use

PCL remains widely supported in enterprise and office laser and multifunction printers. PCL 5 in particular endures as a stable, well-documented target and is used in legacy host and enterprise printing paths — for example, IBM systems' Host Print Transform generates PCL 5 commands. PCL 6 (PCL XL) is a common default for graphical-interface printing on many devices because of its compact binary form and GDI alignment.

For document exchange and increasingly for direct printing, PDF-based workflows and standards-based, driverless printing (such as IPP Everywhere and PWG Raster) have grown, but broad PCL support persists for backward compatibility.

Advantages

• Compact command stream: classic PCL escape sequences are terse, and the PCL 6 binary form is more compact still.
• Historically lightweight to interpret compared with a full PostScript interpreter.
• Very broad device support and a large installed base, with strong backward compatibility across levels.
• Well documented by HP through published technical reference manuals.
• PCL 5 integrates vector graphics via HP-GL/2 and supports scalable fonts.
• PCL 6 Enhanced maps closely to graphical-interface (Windows GDI) drawing, aiding efficient driver output.

Limitations

• PCL is fundamentally device- and print-oriented, not a document-interchange format like PDF and not a general programming language like PostScript.
• Output fidelity depends on the printer's PCL interpreter and available fonts, so behavior can vary across implementations and emulations.
• The classic escape-sequence model is stateful and order-dependent, which can make raw streams awkward to author or debug by hand.
• PCL 6 Enhanced (PCL XL) is binary-only, so it is not human-readable and requires tooling to inspect.
• Two architecturally distinct generations (1 through 5 versus 6/XL) mean "PCL support" can indicate different things on different devices.
• Historically it was weaker in high-end graphic-arts and color-managed workflows, where PostScript and PDF were often preferred.

Related standards and protocols

• HP-GL/2 — HP's vector graphics language, embeddable within PCL 5.
• PJL (Printer Job Language) — HP's job-level control layer for language switching, job separation, and status readback, wrapping PCL and PostScript jobs.
• PostScript (Adobe) — a competing and complementary page-description language.
• PDF (Adobe / ISO 32000) — a document interchange format often converted to PCL for printing.
• IPP and PWG Raster / IPP Everywhere — IETF and PWG driverless-printing standards representing a modern alternative path.
• CUPS — the common Unix, Linux, and macOS printing system that can drive PCL printers.

Timeline

Dates rely largely on secondary reference sources and are given as reported or approximate where HP primary documentation was not directly verifiable; no false precision is asserted.

1. 1984 era

   PCL introduced on HP's early inkjet printers (HP ThinkJet with PCL 1; QuietJet with PCL 1+); basic text and graphics.

2. 1984 era

   PCL 3 associated with the original HP LaserJet; bitmap fonts and raster up to 300 dpi.

3. 1985

   PCL 4 on the HP LaserJet Plus; macros and larger bitmapped fonts and graphics.

4. March 1990 (reported)

   PCL 5 on the HP LaserJet III; Intellifont scalable/outline fonts and HP-GL/2 vector graphics.

5. Early 1990s (reported)

   PJL introduced, reported on the HP LaserJet IIIsi; job-level control.

6. October 1992 (reported)

   PCL 5e on the HP LaserJet 4; bi-directional communication and Windows fonts.

7. circa 1992

   PCL 5c color (HP PaintJet 300XL / Color LaserJet).

8. circa 1995

   PCL 6 (HP LaserJet 5 generation): PCL 6 Enhanced (PCL XL, object-oriented binary) plus PCL 6 Standard (PCL 5-compatible).