Apple Desktop Computer manual Serial Port Compatibility, Macintosh-To-Macintosh Connections

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C H A P T E R 3

Devices and Ports

Serial Port Compatibility

The ﬁrst release of the MacOS USB DDK does not include a universal Serial/ USB shim that would allow processes that use the Communications Toolbox CRM to use a USB serial device. At the introduction of the iMac computer, any USB Serial Class Driver will need to implement its own Serial/USB shim.

The ﬁrst release of the Mac OS USB DDK does not include a universal Serial/ USB shim that would allow processes that use the Communications Toolbox CRM to ﬁnd and use a USB modem device. At the introduction of the iMac computer, any USB modem device would need to implement its own communication shim to interface between the CRM and its USB Communication class driver. For more information, please refer to the Mac OS USB DDK, which is available from the Apple Developer DDK page on the World Wide Web, at

http://developer.apple.com/sdk/

Macintosh-To-Macintosh Connections

USB is a serial communications channel, but it does not replace LocalTalk functionality on Macintosh computers; you cannot connect two Macintosh computers together using the USB. The best method for networking iMac computers is through the built-in Ethernet port.

USB Storage Devices

The Macintosh USB software does not support booting from an external USB storage device.

USB Controller

The iMac computer uses an Open Host Controller Interface (OHCI) controller for USB communication. Some early USB devices (most notably keyboards) can’t interoperate with an OHCI controller. Those devices will not be supported by the Macintosh USB system software.

USB Ports

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Contents Apple iMac Computer Page Contents RAM Expansion Devices and PortsRtas SoftwareRtas NV-RAM Appendix Abbreviations IndexFigures and Tables Page About This Developer Note Contents of This NoteATA Devices PowerPC G3 MicroprocessorSupplemental Reference Documents Mac OSOpen Firmware USB DevicesE F a C E Introduction Features Shows a front view of the computer Case and External FeaturesFront view 2Side view showing I/O bay System Software Compatibility IssuesVideo 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 Ports USB ConnectorsGND Transfer Types SupportedADB Compatibility USB Compatibility IssuesUSB Controller Serial Port CompatibilityMacintosh-To-Macintosh Connections USB Storage DevicesKeyboard Layout KeyboardKeyboard and USB MouseVideo Display Hard Disk DriveSound System Infrared Communication LinkExternal Sound Input Sound InputsSound Outputs Built-in MicrophoneExternal Sound Output Sound SpeciﬁcationsHeadphone Jacks Total harmonic distortion Internal Modem Ethernet PortPage RAM Expansion Expansion Slots Removing the Logic Board AssemblyPlacing the Computer Face Down Unfastening the Cables Removing the bottom coverRAM Expansion Removing the Retaining Screws 3Logic board assembly handle and retaining screwsRemoving the EMI Shield Removing the Logic Board AssemblyLocations of the Expansion Slots 6Locations of the RAM expansion slots Main RAM ExpansionElectrical Design of RAM SO-DIMMs Mechanical Design of RAM SO-DIMMsSdram Devices Conﬁguration of RAM SO-DIMMs Address Multiplexing RAM SO-DIMM Electrical LimitsVideo RAM Expansion Page Software Why Make This Change? What Has Changed Features of the New Approach Data Structures and Files PerformanceRAM Footprint User ExperienceBoot ROM Contents Rtas Mac OS ndrv DriversToolbox Image File Contents Trampoline Code NewWorld Boot ProcessToolBox ROM Image Interrupt Handling What Is DifferentRAM Footprint Outmoded ResourcesStartup Disk Control Panel NanoKernelInterrupt Layout Open Firmware and the Device TreeMachine Identiﬁcation Software Abbreviations Chrp NMI Page Index Nvram X, Y, Z Allen Watson