Printer Control Language - PCL
In computing, PCL or Printer Control Language (Printer Command Language according to Hewlett Packard) is a language to control computer printers, introduced by Hewlett Packard (HP) in 1980. HP has published several new versions since and many other printer manufacturers have adopted the language as a de facto standard.
Typically, the sequence of PCL commands needed to produce a certain printed page comes from the printer driver, a piece of software belonging to the operating system or application program that does the printing. The system sends the resultant command sequence to the printer, which interprets it and produces the page.
In PCL, commands exist to choose a certain font (stored inside the printer), to position the cursor on the page, to transmit a raster image to the printer, etc. These commands take the form of escape sequences: strings of characters that start with the escape character. Newer versions of PCL have an escape sequence to switch on HP-GL mode, which allows for the transmission of vector graphics.
The complexity of PCL lies somewhere between that of ASCII code (which only allows the simplest printer control, such as "carriage return" and "line feed") and that of PostScript (which offers a fully-featured programming language and requires a sophisticated interpreter inside the printer).