Support for PostScript printing

GDDM V3R2 General Information

Support for PostScript printing

GDDM V3R2 General Information
GC33-0866-03

Developed by Adobe systems in 1985, PostScript has, in recent years, become a de facto standard for printing quality output. PostScript is a language that describes to printers exactly how a page is to be printed. PostScript printers usually have a ROM or plug-in cartridge to enable them to interpret the PostScript language. The majority of PostScript printers are monochrome laser or LED technology printers printing at 300 or 600 pixels per inch. Now more and more printers are exploiting PostScript's color capabilities.

The original PostScript language is known as level-1 PostScript and provides a wide range of text and graphics primitives for use in describing a page to be printed. Level 1 has limited support of color and some color PostScript printers, such as the IBM 4079 Color Jetprinter use level 1 of the language with only minor modifications. The newer level-2 PostScript has better color support and is therefore the level used by most current color PostScript printers. Level 2 also allows for compression of image data.

GDDM 3.1.1 supports PostScript printing on the MVS/TSO, MVS/Batch and VM/CMS subsystems as family-4 output. This means that the PostScript output is placed in a file, which can then be routed to a printer by some other software, such as

TCP/IP (transmission control protocol/internet protocol)
PC download to DOS, Windows, and OS/2
PSF/2 for printing level-1 PostScript output on PCL, AFP, or PPDS printers

The PostScript output sent to the file can be primary (PS) or secondary, "encapsulated" (EPS) output. Most of the GDDM processing options that apply to family-4 output can be used when creating PostScript output. Some of the benefits of GDDM's support of PostScript printing are:

Upward compatibility
The new support is upwardly compatible, which implies the following benefits:
- Existing GDDM applications can continue to work unchanged.
- New user default specifications, PostScript device tokens and procopts can be used by new or modified applications to create PostScript output.
- Existing applications can use the new facilities by appropriate customization of GDDM user-default modules or files.
User exits
A user exit is provided to enable your GDDM applications to run programs that print the PostScript files generated.
Color selection
GDDM provides a special color table that you can customize to specify which shade of each color is to be used by the generated PostScript output. In this way, your programs can produce acceptable results on a wide range of color printers.
Font mapping
GDDM also provides a table that can be customized by end users, applications, or for the whole system, to specify how GDDM symbol sets (graphic text) or fonts (presentation text) are mapped to PostScript printer fonts. This enables you to use the large variety of Adobe fonts available for PostScript printers.
"Core Interchange" symbol sets
GDDM now provides the SAA Core Interchange font families, Helvetica, Times New Roman, and Courier, in vector symbol set form. This widens the choice of symbol sets available to all GDDM applications. Applications exploiting the new PostScript support can use these symbol sets to obtain a closer match between screen display and printed output.

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