Apple Desktop Computer manual Main RAM Expansion, 6Locations of the RAM expansion slots

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C H A P T E R 4

RAM Expansion

Figure 4-6Locations of the RAM expansion slots

Video RAM slot

Main RAM top slot

Main RAM bottom slot

Main RAM Expansion

The iMac computer has two RAM expansion slots that accommodate standard SO (small outline) DIMMs using SDRAM devices.

IMPORTANT

RAM expansion SO-DIMMs for the iMac must use SDRAM devices. If the user installs an SO-DIMM that uses EDO or SGRAM devices, the computer will beep several times when the user attempts to restart the computer. ▲

An SO-DIMM for the iMac can contain either 16, 32, or 64 MB of memory.

48Main RAM Expansion

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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 SoftwareMain RAM Expansion Modules Video RAM Expansion ModulesUSB Ports and Devices Page Architecture Architecture Processor module G3 MicroprocessorBackside Cache Main Logic Board Memory Controller and PCI BridgeController IC USB Controller Video Display SubsystemBuilt-in Modem 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 InputSound Speciﬁcations External Sound OutputHeadphone Jacks Total harmonic distortion Ethernet Port Internal ModemPage RAM Expansion Removing the Logic Board Assembly Expansion SlotsPlacing 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 Performance RAM FootprintUser Experience Data Structures and FilesBoot ROM Contents Mac OS ndrv Drivers RtasToolbox Image File Contents NewWorld Boot Process Trampoline CodeToolBox ROM Image What Is Different Interrupt HandlingOutmoded Resources RAM FootprintNanoKernel Startup Disk Control PanelOpen Firmware and the Device Tree Interrupt LayoutMachine Identiﬁcation Software Abbreviations Chrp NMI Page Index Nvram X, Y, Z Allen Watson