Apple iMac Manuel d'utilisateur télécharger pdf (Page 62)

CHAPTER 5

Software

62 Toolbox Image File Contents

RTAS is relocateable code; its location in RAM is determined by the OS, and it

remains functional after the OS boots.

Note

RTAS is part of the system software. It is not needed by

applications, which use operating system APIs. ◆

Toolbox Image File Contents 5

The Toolbox image file (also called the bootinfo ﬁle) contains three main

components, each of which is made up of smaller components: the pieces that

are part of the bootinfo speciﬁcation, the Trampoline code, and the ToolBox

ROM Image itself.

Most changes needed for a new CPU occur in the Boot ROM, not in the bootinfo

ﬁle. Changes to the ToolBox ROM Image should be limited to new manager

software and support for hardware that is common to many Macintosh

computers (ATA interface modules, user interface modules, and the like).

The bootinfo ﬁle exists on the boot device and has a localizable name.

Identiﬁcation information that leads to the ﬁle’s path is stored in NV-RAM and

the search algorithm for a usable bootinfo ﬁle parallels the search mechanism

across SCSI, ATA, etc., used in the former startup disk routine. By default, the

ﬁle is located by using the directory ID of the “blessed folder” in the boot block

of each HFS or HFS Plus partition, and then searching for a ﬁle with a ﬁle type

'tbxi'. Searching by ﬁle type is done to allow localization of the ﬁle.

Non-localized, the name of the bootinfo ﬁle is “Mac OS ROM”.

Open Firmware Script 5

The bootinfo components normally do not need to be changed for each new

product. The Open Firmware script is automatically modiﬁed at build time to

have the correct offsets within the bootinfo ﬁle to the other two main

components.

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Apple iMac Manuel d'utilisateur Page 62