Windows 8 Bible

How Printing Works

When you print a document, quite a bit of work takes place invisibly in the background before the printer even “knows” there’s a document to print. First, a program called a print spooler (or spooler for short) makes a special copy of the document that contains instructions that tell the printer exactly what to do. Those instructions don’t look anything like the document you’re printing. They’re just codes that tell the printer what to do so that the document it spits out ends up looking like the document that you printed.

After the spooler creates the special printer file, it can’t just hand the whole thing off to the printer as one giant set of instructions. Most printers are slow mechanical devices that can hold only a small amount of information at a time in a buffer. The buffer is a storage area within the printer that holds the data to be printed until it is printed. The amount of data that can reside in the buffer depends on the size of the buffer. In some cases, the buffer will hold a large number of pages. In others, it might hold only a single page, or in the case of a complex document such as a photo, and a relatively small buffer, only part of the page might fit in the buffer at one time.

Furthermore, when the spooler has finished creating the special printer file, another document may already be printing. There may even be several documents waiting to be printed. So, the spooler has to put all the print jobs into a queue (line). All of this activity ...