Apple iMac Manual de usuario

 Technical Publications© Apple Computer, Inc. 1998  Developer Note Apple iMac Computer Developer Note

10 PREFACE Supplemental Reference Documents 0 For more information about the technologies mentioned in this developer note, you may wish to consult

11 PREFACE USB Devices 0 For more information about USB on the Macintosh computer, developers should refer to Apple Computer’s Mac OS USB DDK ATI Re

12 PREFACE IEEE Std 1275-1994 Standard for Boot (Initialization, Configuration) Firmware (Version 1.7)Open Firmware Recommended Practice: Device Sup

13 CHAPTER 1 Introduction 1Figure 1-0Listing 1-0Table 1-0

CHAPTER 1 Introduction 14 Features The Apple iMac computer is a new consumer-oriented desktop computer. This chapter summarizes the features of this

CHAPTER 1 IntroductionCase and External Features 15 Modem: The computer has a built-in modem with 56 Kbps data rate. For more information, see “In

CHAPTER 1 Introduction 16 Case and External Features Figure 1-1 Front view The front of the case is dominated by the 15-inch display. The front als

CHAPTER 1 IntroductionCase and External Features 17 Figure 1-2 Side view showing I/O bay Sound input portSound output portUniversal Serial Bus (USB)

CHAPTER 1 Introduction 18 Compatibility Issues The back of the case contains the receptacle for the power cord and a small folding handle for use in

CHAPTER 1 IntroductionCompatibility Issues 19 Main RAM Expansion Modules 1 For expansion of main RAM, the iMac computer uses standard SO-DIMMs that

 Apple Computer, Inc.© 1998 Apple Computer, Inc.All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or

21 CHAPTER 2 Architecture 2Figure 2-0Listing 2-0Table 2-0

CHAPTER 2 Architecture 22 The components at the heart of the iMac computer reside on two printed-circuit boards: the main logic board and the proces

CHAPTER 2 ArchitectureProcessor module 23 Processor module 2 The processor module contains the high-speed components: G3 microprocessor 512 KB

CHAPTER 2 Architecture24 Main Logic Boardprocessor’s clock speed, rather than at the clock speed of the main system bus. In the iMac, the clock speed

CHAPTER 2ArchitectureMain Logic Board 25 the built-in modem the infrared link the Ethernet port the sound ASIC the internal IDE hard drive the

CHAPTER 2 Architecture26 Main Logic BoardInfrared Link Module 2The infrared link module is a separate printed circuit board that is connected to SCC p

27CHAPTER 3Devices and Ports 3Figure 3-0Listing 3-0Table 3-0

CHAPTER 3 Devices and Ports28 USB PortsThis chapter describes both the built-in I/O devices and the ports for connecting external I/O devices. Each of

CHAPTER 3Devices and PortsUSB Ports 29Figure 3-1 USB Type A port and connector The iMac computer provides 5-volt power at 500 mA for each of the two p

3 Contents Figures and Tables 7 Preface About This Developer Note 9Contents of This Note 9Supplemental Reference Documents 10PowerPC G3 Microprocesso

CHAPTER 3 Devices and Ports30 USB Ports Interrupt transfers, used for human interface device (HID) class devices such as keyboards and mice, as well

CHAPTER 3Devices and PortsUSB Ports 31Serial Port Compatibility 3The first release of the MacOS USB DDK does not include a universal Serial/USB shim th

CHAPTER 3 Devices and Ports32 KeyboardKeyboard 3The Apple USB keyboard has a total of 82 keys, including 12 function keys, a numeric keypad and a set

CHAPTER 3Devices and PortsMouse 33Keyboard and USB 3The Apple USB keyboard is designed to work with the iMac computer by way of the USB ports. The key

CHAPTER 3 Devices and Ports34 Hard Disk DriveThe mechanism inside the Apple USB mouse is similar to that in the Apple Desktop Bus Mouse II. The mouse

CHAPTER 3Devices and PortsInfrared Communication Link 35Infrared Communication Link 3The iMac computer has a direct infrared (IR) communication link

CHAPTER 3 Devices and Ports36 Sound SystemSound Inputs 3The sound system accepts inputs from three possible sources: built-in microphone external st

CHAPTER 3Devices and PortsSound System 37 during power cyclingExternal Sound Output 3The external sound output jack is a 3.5-mm mini phone jack locat

CHAPTER 3 Devices and Ports38 Sound SystemTotal harmonic distortion plus noise (THD+N) as a percentage of full scale for various outputs are shown in

CHAPTER 3Devices and PortsEthernet Port 39Ethernet Port 3The iMac computer has a built-in 10/100 Mbps Ethernet port. The user can connect it to eithe

4 Infrared Link Module 26 Chapter 3 Devices and Ports 27USB Ports 28USB Connectors 28Transfer Types Supported 29USB Compatibility Issues 30ADB Compat

41CHAPTER 4RAM Expansion 4Figure 4-0Listing 4-0Table 4-0

CHAPTER 4 RAM Expansion42 The Expansion SlotsThis chapter tells how to gain access to the expansion slots in the iMac computer and describes the two t

CHAPTER 4RAM ExpansionThe Expansion Slots 43Figure 4-1 Bottom view showing bottom cover handle Removing the bottom cover 4The bottom cover is held in

CHAPTER 4 RAM Expansion44 The Expansion SlotsFigure 4-2 Cables connected to the logic board assembly

CHAPTER 4RAM ExpansionThe Expansion Slots 45Removing the Retaining Screws 4A slot-shaped handle is located at the back end of the logic board assembly

CHAPTER 4 RAM Expansion46 The Expansion SlotsRemoving the Logic Board Assembly 4With the retaining screws removed and the cables positioned to the sid

CHAPTER 4RAM ExpansionThe Expansion Slots 47Figure 4-5 EMI shieldLocations of the Expansion Slots 4Figure 4-6 shows the location of the two main RAM e

CHAPTER 4 RAM Expansion48 Main RAM ExpansionFigure 4-6 Locations of the RAM expansion slots Main RAM Expansion 4The iMac computer has two RAM expansi

CHAPTER 4RAM ExpansionMain RAM Expansion 49Total RAM capacity using devices currently available is 128 MB and is limited by the space available for th

5 Placing the Computer Face Down 42Removing the bottom cover 43Unfastening the Cables 43Removing the Retaining Screws 45Removing the Logic Board Asse

CHAPTER 4 RAM Expansion50 Main RAM ExpansionThe JEDEC specification for the SO-DIMM defines a Serial Presence Detect (SPD) feature that contains the att

CHAPTER 4RAM ExpansionMain RAM Expansion 51Configuration of RAM SO-DIMMs 4Table 4-1 shows the sizes of the RAM expansion modules that can be used in th

CHAPTER 4 RAM Expansion52 Main RAM ExpansionAddress Multiplexing 4Signals A[0] – A[13] on each RAM SO-DIMM make up a 14-bit multiplexed address bus th

CHAPTER 4RAM ExpansionVideo RAM Expansion 53Active 1.2 A (8 devices at 150 mA each)Sleep 6 mA per bankThe maximum current specified for active operatio

55CHAPTER 5Software 5Figure 5-0Listing 5-0Table 5-0

CHAPTER 5 Software56 Why Make This Change?The Apple iMac computer is different from previous Macintosh computers in that it has no single, large ROM t

CHAPTER 5SoftwareWhy Make This Change? 57• Not changing the higher level software as often simplifies things for many groups inside Apple, including te

CHAPTER 5 Software58 Why Make This Change?Features of the New Approach 5Because the iMac has new hardware features that are different from other Macin

CHAPTER 5SoftwareWhy Make This Change? 59Performance 5Performance of an iMac computer using ROM in RAM should exceed performance measurements for oth

6 Interrupt Handling 64Outmoded Resources 65RAM Footprint 65RTAS 65NV-RAM 65NanoKernel 66Startup Disk Control Panel 66Open Firmware and the Device T

CHAPTER 5 Software60 Boot ROM Contentsin RAM appears to be a ROM, the ROM-in-RAM approach is completely compatible with all application and system sof

CHAPTER 5SoftwareBoot ROM Contents 61Failure to boot in POST causes the error beep, optionally entering the Mini-Nub. Open Firmware 5The Open Firmware

CHAPTER 5 Software62 Toolbox Image File ContentsRTAS is relocateable code; its location in RAM is determined by the OS, and it remains functional afte

CHAPTER 5SoftwareNewWorld Boot Process 63Trampoline Code 5The Trampoline code is the component of the NewWorld architecture that handles the transiti

CHAPTER 5 Software64 What Is Different5. The Forth script transfers control to the Trampoline code, which functions as the transition between Open Fir

CHAPTER 5SoftwareWhat Is Different 65that interrupt latency has been reduced to such an extent as to make it negligible. The other is that the interru

CHAPTER 5 Software66 What Is Differentvariable-sized partitions that are used by Mac OS, Open Firmware, and any other client. PRAM resides in the Mac

CHAPTER 5SoftwareWhat Is Different 67Once Open Firmware locates a startup device and successfully loads a Mac OS ROM, image it passes information abou

CHAPTER 5 Software68 What Is DifferentToolBox ROM Image, so sharing the same Box Flag is not an issue for those areas. IMPORTANTPrograms such as contr

69APPENDIX Abbreviations AStandard units of measure used in this note include:Other abbreviations used in this note include:A amperes MB megabytes dB

7 Figures and Tables Chapter 1 Introduction 13 Figure 1-1 Front view 16 Figure 1-2 Side view showing I/O bay 17 Chapter 2 Architecture 21 Figure

APPENDIX A Abbreviations70CHRP Common Hardware Reference PlatformCPU central processing unitCRM Communications Resource ManagerCRT cathode ray tube, a

APPENDIX AAbbreviations71NMI nonmaskable interruptNV-RAM nonvolatile random-access memoryOHCI Open Host Controller Interface OS operating systemPCI Pe

73IndexAATA Device Software Guide 10, 34ATA disk interface 34ATA hard disk 34ATI Rage IC 25Bbackside cache 23Boot ROM 57contents 60–62Box Flag 68Ccach

INDEX74Kkeyboard 32–33LL2 cache 23Mmachine ID 67Macintosh ROM, why it’s changing 56–60Mac OS 8.1 10Mac OS ROM file 59Mac OS ROM image 58Mac OS ToolBox

INDEX75Run-Time Abstraction Services. See RTASSSDRAM device specifications 50serial presence detect, on SO-DIMM 50SGRAM 53SO-DIMMs, for RAM expansion 4

THE APPLE PUBLISHING SYSTEMThis Apple manual was written, edited, and composed on a desktop publishing system using Apple Macintosh computers and Fram

9 PREFACE About This Developer Note This developer note is a concise description of the iMac ™ computer, with the emphasis on the features that are