Apple Personal LaserWriter NTR Specifications download pdf (Page 37)

CHAPTER 2

PostScript Software

Resource Categories 27

Engine Device Parameters 2

The %Engine% device contains parameters that control the print engine itself. The

Personal LaserWriter 320 printer’s %Engine% device contains the parameters listed

in Table 2-9.

Resource Categories 2

In PostScript language Level 2, PostScript objects such as fonts, patterns, and ﬁlters can

be managed as open-ended collections of resources grouped into categories. A resource

is requested by resource category and name. If the resource does not reside in virtual

memory, the resource management mechanism loads it from an external source, such as

a disk, a ROM cartridge, or a network ﬁle server. The PostScript Language Reference

Manual, second edition, discusses named resources in detail.

There are several groups of resources:

■ New resources in the regular resource categories can be added. These include such

items as font and pattern resources (see Table 2-10).

■ Categories of implicit resources represent built-in capabilities of the Personal

LaserWriter 320 interpreter. For example, the FormType category indicates that

the interpreter understands Type 1 only (see Table 2-11).

■ Some resources are used to deﬁne new categories (see Table 2-12).

Most of the instances listed in the following tables are described in the PostScript

Language Reference Manual, second edition, or the PostScript Language Reference

Manual Supplement.

Table 2-9 %Engine% communication parameters

Key Type Default Details

Darkness real 0.484375 Controls the amount of toner applied to the paper. A

value of 0.0 signiﬁes the minimum darkness, and a value

of 1.0 signiﬁes the maximum darkness. Values outside

this range are not legal. The Personal LaserWriter 320

printer supports 16 levels of darkness, so this parameter

is divided into 16 steps. Multiply the integer portion

of Darkness by 15. Therefore, a value of 0.0 is not

distinguishable from 0.05, but it is distinguishable from

0.1. Changes in the Darkness parameter are not sent to

the engine until there are no pages in the paper path,

either feeding or being copied.

This value persists across power cycles and restarts.

Type name /Parameters This read-only constant always returns a value of

/Parameters.

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Apple Personal LaserWriter NTR Specifications Page 37