Apple Desktop Computer manual Features

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C H A P T E R 1

Introduction

The Apple iMac computer is a new consumer-oriented desktop computer. This chapter summarizes the features of this new computer and points out issues affecting compatibility.

Features

Here is a list of the features of the iMac computer. Each feature is described in more detail in a later chapter.

■Processor: The iMac has a PowerPC G3 microprocessor running at a clock speed of 233 MHz. For more information, see “G3 Microprocessor” (page 23).

■Cache: The iMac has a backside L2 cache consisting of 512 KB of fast static RAM. The clock speed for the backside cache is half the clock speed of the microprocessor. For more information, see “Backside Cache” (page 23).

■Memory: The iMac has two standard SO-DIMM expansion slots for SDRAM modules. The computer comes with 32 MB of SDRAM installed. RAM is expandable up to 128 MB total, using presently available memory devices. For more information, see “Main RAM Expansion” (page 48).

■Hard disk storage: The iMac has a built-in hard disk drive with a capacity of 4 GB. For more information, see “Hard Disk Drive” (page 34).

■CD-ROM drive: The iMac has a built-in CD-ROM drive with 24X speed.

■Display: The iMac has a built-in 15-inch color monitor (13.8-inch viewable diagonal). The monitor can display with resolutions of 640 by 480, 800 by 600, or 1024 by 768 pixels. For more information, see “Video Display” (page 34).

■Video RAM: The iMac comes with 2 MB of video SGRAM, which supports millions of colors on displays up to 800 by 600 pixels and thousands of colors on a display with 1024 by 768 pixels. The computer has one expansion slot for a second 2 or 4 MB SGRAM DIMM, which allows the computer to display millions of colors on a display with 1024 by 768 pixels. For more information, see “Video RAM Expansion” (page 53).

■Graphics acceleration: The video circuits provide built-in 2D and 3D acceleration using an ATI Rage IIc IC.

■USB ports: The computer has two USB ports for keyboard, mouse, and other USB devices, described in “USB Ports” (page 28).

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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 Devices USB 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
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