Apple Desktop Computer manual Toolbox Image File Contents

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C H A P T E R 5

Software

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

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 of '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

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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Contents Apple iMac Computer Page Contents Devices and Ports RAM ExpansionSoftware RtasAppendix Abbreviations Index Rtas NV-RAMFigures and Tables Page Contents of This Note About This Developer NoteMac OS PowerPC G3 MicroprocessorSupplemental Reference Documents ATA DevicesUSB Devices Open FirmwareE F a C E Introduction Features Case and External Features Shows a front view of the computerFront view 2Side view showing I/O bay Compatibility Issues System SoftwareUSB Ports and Devices Main RAM Expansion ModulesVideo RAM Expansion Modules Page Architecture Architecture Backside Cache Processor moduleG3 Microprocessor Controller IC Main Logic BoardMemory Controller and PCI Bridge Built-in Modem USB ControllerVideo Display Subsystem Infrared Link Module Devices and Ports USB Connectors USB PortsTransfer Types Supported GNDUSB Compatibility Issues ADB CompatibilityUSB Storage Devices Serial Port CompatibilityMacintosh-To-Macintosh Connections USB ControllerKeyboard Keyboard LayoutMouse Keyboard and USBHard Disk Drive Video DisplayInfrared Communication Link Sound SystemBuilt-in Microphone Sound InputsSound Outputs External Sound InputHeadphone Jacks Sound SpeciﬁcationsExternal Sound Output Total harmonic distortion Ethernet Port Internal ModemPage RAM Expansion Placing the Computer Face Down Removing the Logic Board AssemblyExpansion Slots Removing the bottom cover Unfastening the CablesRAM Expansion 3Logic board assembly handle and retaining screws Removing the Retaining ScrewsRemoving the Logic Board Assembly Removing the EMI ShieldLocations of the Expansion Slots Main RAM Expansion 6Locations of the RAM expansion slotsMechanical Design of RAM SO-DIMMs Electrical Design of RAM SO-DIMMsSdram Devices Conﬁguration of RAM SO-DIMMs RAM SO-DIMM Electrical Limits Address MultiplexingVideo RAM Expansion Page Software Why Make This Change? What Has Changed Features of the New Approach User Experience PerformanceRAM Footprint Data Structures and FilesBoot ROM Contents Mac OS ndrv Drivers RtasToolbox Image File Contents ToolBox ROM Image NewWorld Boot ProcessTrampoline Code What Is Different Interrupt HandlingOutmoded Resources RAM FootprintNanoKernel Startup Disk Control PanelMachine Identiﬁcation Open Firmware and the Device TreeInterrupt Layout Software Abbreviations Chrp NMI Page Index Nvram X, Y, Z Allen Watson