A print device is the actual hardware device that produces printed output—what you call a "printer" in casual conversation.
Print-device resolution is measured in dots per inch (DPI). The higher the DPI, the finer the resolution.
A printer, or logical printer, is the software interface between the operating system and print device. The printer determines how the document gets to the printing devices (for example, by means of a local port or to a remote print share) and to other parameters of the printing process. A single printer can send print jobs to multiple print devices, and multiple printers can send jobs to a single print device. For more detail about printers and print devices, see "Planning How Users Access Printers" in Microsoft Windows NT Server: Concepts and Planning Guide. In the NetWare and OS/2 environments, this software interface is called a queue.
In Windows NT terminology, a queue is a group of documents waiting to be printed.
Print jobs are source code that contain both data and commands for print processing.
Print jobs are classified into data types based on what modifications, if any, the spooler must make to the job so that it prints correctly. For example, one data type requires no modifications, whereas another data type requires the addition of a form feed to the end of the job.
The print spooler is a collection of dynamic-link libraries (DLLs) that receives, processes, schedules, and distributes print jobs.
Spooling is only one of the processes performed by the spooler. Spooling is the process of writing the contents of a print job to a file on disk. This file is called a spool file. In the event of power loss during printing, the spool file prevents loss of data, ensuring that the print job can resume after power is restored. Despooling is the process of reading the contents from a spool file and sending those contents to a print device.
Rendering means creating a print job. An application calls the graphics device interface (GDI). GDI takes the document information sent by the application, calls the printer driver associated with the target print device, and creates a print job in the printer language of the print device. The print device has "firmware" that interprets the submitted printer language and creates a bitmap for each page.
A print server is the computer that connects one or more print devices to the network and shares them with other networked computers. A print server can also be a special hardware device that connects a print device to the network with a net tap on one side and a parallel or serial port on the other side.
This chapter presumes that the print server is a Windows NT 4.0 Workstation.
A downlevel server is a print server running a Windows product that is not Windows NT 4.0—for example, Windows for Workgroups or Windows NT 3.x.
Creating a printer means connecting to the print device, either over the network or over a serial or parallel port, naming the printer, and installing the printer driver. To create a printer, run the Add Printer wizard, and click the Local printer option. You'll be asked to install the printer driver, specify a port, and give the printer a name.
Connecting to a printer means connecting to the share on the computer that created the printer. To connect to a printer, run the Add Printer wizard, and click the Network printer option. You won't be required to install the printer driver. Only Windows NT and Windows 95 clients can "connect to" a printer shared out by a Windows NT 4.0 print server. Other print clients must "create" the printer shared by the Windows NT print server.
A print client is the computer that creates the print job sent to a Windows NT print server. The client can be a remote client sending the print job to the print server over a LAN. Or the client can be on the print server itself—a local client. This chapter presumes that most printing done with Windows NT Workstation is local.
A client application is any application that creates a print job. The client application can be local (on the print server) or it can be on a client computer on the network.
Network-interface printers are print devices connected directly to the network by means of their own network cards.
Print server services are software modules on the print server that receive print jobs and determine if the spooler should alter them. Different print server services support print jobs from various clients.
Printer drivers are software programs that enable applications to communicate fully and properly with print devices. Each print device can require unique codes and commnds to make available its special features, such as two-sided printing or custom paper sizes.
Anything described as local means that it exists on the same computer.