Apple Desktop Computer manual Hard Disk Drive, Video Display

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C H A P T E R 3

Devices and Ports

The mechanism inside the Apple USB mouse is similar to that in the Apple Desktop Bus Mouse II. The mouse ball is removeable for cleaning; the ring that allows access to the ball can be locked by inserting an unfolded paper clip into a small hole and turning the ring clockwise.

Hard Disk Drive

The iMac computer has an internal hard disk drive. The drive uses the extended IDE (integrated drive electronics) interface, which is also referred to as the ATA interface. The implementation of the ATA interface on these computers is a subset of the ATA/IDE speciﬁcation, ANSI proposal X3T10/0948D, Revision 3 (ATA-3).

The software that supports the internal hard disk is the same as that in previous Macintosh PowerBook models with internal IDE drives and includes DMA support. For the latest information about that software, see Technote #1098, ATA Device Software Guide Additions and Corrections, available on the world wide web at

http://developer.apple.com/technotes/tn/tn1098.html

The web page for Technote #1098 includes a link to a downloadable copy of ATA Device Software Guide.

Video Display

The built-in video display uses a 15-inch CRT (13.8-inch viewable diagonal). The CRT uses shadow-mask technology and has a dot pitch of 0.28 mm. The display is multi-scan and supports three resolutions. Table 3-2 lists the resolutions and the pixel depths supported with either the standard 2 MB of SGRAM or with expanded SGRAM.

34Hard Disk Drive

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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 SoftwareVideo RAM Expansion Modules Main RAM Expansion ModulesUSB Ports and Devices Page Architecture Architecture G3 Microprocessor Processor moduleBackside Cache Memory Controller and PCI Bridge Main Logic BoardController IC Video Display Subsystem USB ControllerBuilt-in Modem Infrared Link Module Devices and Ports USB Connectors USB PortsTransfer Types Supported GNDUSB Compatibility Issues ADB Compatibility USB Storage Devices Serial Port Compatibility Macintosh-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 InputExternal Sound Output Sound SpeciﬁcationsHeadphone Jacks Total harmonic distortion Ethernet Port Internal ModemPage RAM Expansion Expansion Slots Removing the Logic Board AssemblyPlacing the Computer Face Down 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 Trampoline Code NewWorld Boot ProcessToolBox ROM Image What Is Different Interrupt HandlingOutmoded Resources RAM FootprintNanoKernel Startup Disk Control PanelInterrupt Layout Open Firmware and the Device TreeMachine Identiﬁcation Software Abbreviations Chrp NMI Page Index Nvram X, Y, Z Allen Watson