Apple Desktop Computer manual Software

Page 68

C H A P T E R 5

Software

ToolBox ROM Image, so sharing the same Box Flag is not an issue for those areas.

IMPORTANT

Programs such as control panels and installers that use Box Flag to verify that this is a valid CPU on which to execute need to be changed to verify the existence of the hardware they require. Developers should look for the features they need, rather than reading the Box Flag and then making assumptions about the computer’s features. ▲

Asset management software that reports the kind of machine it is run on should check the name registry for the value of the property at Devices:device-tree:model. For the current iMac, the property value is iMac,1.

68What Is Different

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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 NotePowerPC G3 Microprocessor Supplemental Reference DocumentsMac OS 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 CompatibilitySerial Port Compatibility Macintosh-To-Macintosh ConnectionsUSB Storage Devices USB ControllerKeyboard Keyboard LayoutMouse Keyboard and USBHard Disk Drive Video DisplayInfrared Communication Link Sound SystemSound Inputs Sound OutputsBuilt-in Microphone 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 Performance RAM FootprintUser Experience 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