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Technical Q&As are short question and answer formatted pages that provide answers to questions frequently received at Apple Developer Technical Support.

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Ejecting the Volume on Which Your Program Resides (HTML) ()
FL09: Suggests different solutions regarding ejecting a disk on which an application resides.
Hardware 1998-07-06
Empty Memory Objects (HTML) ()
QA1259: Describes how two memory management edge cases are handled by the common Mac OS memory allocators.
Hardware 2003-04-21
Energy Star PCI Device (HTML) ()
QA1108: Provides useful information for developers of Energy Star-compliant PCI devices.
Hardware 2002-01-15
Expansion ROM device properties (HTML) ()
HW50: Describes the Open Firmware properties that should be included in a boot device's expansion ROM.
Hardware 1999-03-29
Explanation of SDRAM configuration Nomenclature (HTML)
HW75: Explains the three-part "Device configuration" numbers for SDRAM in the Power Mac G4 Computer Developer Note.
Hardware 1999-10-18
Faster DDR DRAM in the 867MHz Power Mac G4 (Mirrored Drive Doors) (HTML) ()
QA1191: Confirms the use of faster DDR DRAM in the 867MHz Power Mac G4 (Mirrored Drive Doors).
Hardware 2002-08-19
FCode & OS X (HTML) ()
QA1106: Provides useful tips for Open Firmware debugging on on machines introduced in 2001 or later.
Hardware 2002-01-15
Generating an NMI Without a Programmer's Switch (HTML) ()
QA1264: Explains how to generate a non-maskable interrupt (NMI) on CPUs without programmer's switches.
Hardware 2004-04-26
Getting a List of Drivers & LUNs (logical unit numbers) (HTML)
Deprecated - DV04: Describes a legacy Mac OS technique for obtaining a list of SCSI Parallel drivers, devices, and LUNs.
Hardware 1995-07-01
Getting a Packet Trace (HTML) ()
QA1176: Lists tools available for looking at the network packets on the wire.
Hardware 2004-07-13
Getting started with Forth (HTML) ()
HW53: Describes where FCode driver developers can get information about the Forth programming language.
Hardware 1999-03-29
The "green" PCI bus (HTML)
HW93: Explains why the PCI bus is considered "green".
Hardware 2000-09-05
HID Manager Event Data Underruns (HTML)
QA1038: Explains how to correctly handle HID Manager event queue data underruns.
Hardware 2001-06-13
How can I tell if a PCI device has on board I/O space? (HTML)
QA1287: Demonstrates "how to" tell if a PCI device has on board I/O space.
Hardware 2003-09-24
How do I change the numeric base for the Open Firmware user interface? (HTML)
HW66: Explains how to change the numeric base for the Open Firmware user interface.
Hardware 1999-10-11
How do I determine the top of the Open Firmware dictionary? (HTML)
HW69: Explains how to determine the top of the Open Firmware dictionary.
Hardware 1999-10-11
How does Open Firmware generate the name property? (HTML) ()
HW39: Describes the Open Firmware name property generation process.
Hardware 1999-02-15
How many PCI header types exist today? (HTML)
HW92: Briefly describes the three PCI header types defined in the PCI 2.2 specification.
Hardware 2000-09-05
if and then in Forth (HTML) ()
HW54: Using the Forth word "if" requires a "then".
Hardware 1999-03-29
Installing an I/O Kit KEXT Without Rebooting (HTML)
QA1319: Describes the state of the art of installing I/O Kit kernel extensions (KEXTs) without requiring a restart.
Hardware 2003-10-28
Invoking the Open Firmware user interface (HTML) ()
HW45: Describes how to invoke the Open Firmware user interface on startup.
Hardware 1999-02-15
IODeviceTree & the IORegistry (HTML) ()
QA1120: Describes the IODeviceTree plane in the Mac OS X IORegistry.
Hardware 2002-02-13
IOKit Framework Headers (HTML) ()
QA1107: Describes the differences between the headers in IOKit.framework and the I/O Kit headers in Kernel.framework.
Hardware 2002-01-15
IOLog and Interrupt Context (HTML) ()
QA1100: Describes when IOKit runs at primary (hardware) interrupt context.
Hardware 2002-02-13
Is the Open Firmware device tree object oriented? (HTML)
HW80: Discusses the object-oriented attributes of the Open Firmware device tree.
Hardware 1999-11-15
Issues with boot time KEXT loading (HTML) ()
QA1087: Explains how to solve problems with loading KEXTs at boot time.
Hardware 2004-01-15
Legacy Devices (HTML)
HW84: Discusses why legacy devices with hard-wired I/O addresses may not work properly with Open Firmware.
Hardware 2000-03-20
Locating the 1275-1994 Standard Document (HTML)
HW85: Alerts that the Open Firmware (IEEE 1275-1994) document can't be found at the IEEE Standards Association site.
Hardware 2000-07-17
Mac OS X and root access (HTML)
QA1013: Describes how to enable root access in Mac OS X.
Hardware 2001-03-13
Making sense of IOKit error codes (HTML) ()
QA1075: Explains how to interpret I/O Kit error codes.
Hardware 2002-02-07
Maximum Memory for the "Firewire" PowerBook (HTML)
Deprecated - HW83: Discrepancies between PowerBook Developer Note and TIL articles 14870 and 58582, regarding maximum memory configurations.
Hardware 2000-03-13
Menu Bar Clock and NVRAM (HTML)
QA1102: Explains why booting with the Command-Option-P-R keys doesn't reset date and time preferences.
Hardware 2001-12-21
Obtaining the name of an external MIDI Device from a MIDI Endpoint (HTML)
QA1374: Get the names of external MIDI Devices from MIDI Endpoints.
Hardware 2004-12-01
Open Firmware and the devalias node (HTML)
HW95: Describes why the contents of the Open Firmware devalias node varies between Macintosh models.
Hardware 2000-09-05
Open Firmware device tree nodes (HTML)
HW86: Explains the usage of the "@n" notation in Open Firmware device tree nodes.
Hardware 2000-09-05
Open Firmware Memory bus speed (HTML)
HW97: Describes a method to display memory bus speed for G3 or G4 Macintosh in Open Firmware.
Hardware 2000-09-22
Open Firmware version number (HTML)
HW96: Discusses the unique values of Open Firmware version numbers.
Hardware 2000-09-22
OTScheduleDeferredTask When Task Running (HTML) ()
NW52: Describes what happens when you use OTScheduleDefferedTask to schedule a task that is running.
Hardware 1997-10-13
The "packages" node in the device tree (HTML)
HW90: Describes the "packages" node in the Open Firmware device tree.
Hardware 2000-09-05
PC100 SDRAM DIMMs on the Flat Panel iMac (HTML) ()
QA1130: Describes PC100 SDRAM DIMM limitations on the "original " Flat Panel iMac.
Hardware 2002-03-18
PCI address/data stepping (HTML)
HW94: Explains that Apple does not support PCI address/data stepping.
Hardware 2000-09-05
PCI bus on the iMac (HTML) ()
HW42: Explains that the iMac has a PCI bus even though it has no expansion slots.
Hardware 1999-02-15
PCI Bus? (HTML)
QA1104: Answers the question, "Do all Macintosh computers have a PCI bus?"
Hardware 2001-12-21
PCI class codes (HTML)
HW91: Explains why PCI class codes are important.
Hardware 2000-09-05
PCI Header types (HTML)
HW78: Describes the three required types of PCI headers to be provided in its configuration header space.
Hardware 1999-11-15
PCI Macintoshes and CardBus controllers (HTML)
HW87: Explains why older PCI Macintoshes do not recognize a Cardbus controller.
Hardware 2000-09-05
PCI SIG (HTML) ()
HW55: Describes the meaning of the acronym PCI SIG.
Hardware 1999-03-29
PCI Type 1 Cycles (HTML)
HW26: Describes the circumstances when the PowerMac generates a Configuration Type 1 command.
Hardware 1995-07-15
PCI/PCI-X slots on the Power Mac G5 (HTML)
QA1307: Discusses installing PCI/PCI-X cards of different speeds in the Power Mac G5.
Hardware 2003-09-30
Power adapter Sensing for the 17" PowerBook (HTML) ()
QA1266: Details Design and detection considerations for 17-inch PowerBook power adapters
Hardware 2003-06-12
Power Management; Policy Maker vs. Power Controller (HTML) ()
QA1121: Describes the differences between a Power Management Policy Maker and a Power Management Power Controller.
Hardware 2002-02-13
PrepareMemoryForIO in the NewWorld (HTML)
DV33: Explains the correct use of PrepareMemoryForIO on DMA buffers when writing a device driver for DMA software.
Hardware 1998-12-07
Programmatically causing restart, shutdown and/or logout (HTML) ()
QA1134: Describes how to programmatically cause restart, shutdown, sleep or logout.
Hardware 2003-02-10
Reducing the size of Physical Memory in Open Firmware (HTML)
QA1099: Describes how to configure the Power Macintosh so less memory is recognized than is actually present.
Hardware 2001-12-20
Registering a Rendezvous service multiple times (HTML)
QA1311: Explains why registering the same Rendezvous service twice on the same machine doesn't cause a name conflict.
Hardware 2003-10-23
Rendezvous enforces the service type format in Panther (HTML)
QA1198: Explains why registering a Rendezvous service might fail on Panther.
Hardware 2004-03-23
Rendezvous service types used in Mac OS X (HTML)
QA1312: Provides a list of common Rendezvous service types used in Mac OS X.
Hardware 2004-07-14
Rendezvous TXT record rate limiting in Panther (HTML)
QA1293: Explains how mDNSResponder implements TXT record rate limiting in Panther.
Hardware 2003-10-23
Resetting NVRAM to factory defaults (HTML)
QA1103: Describes what happens when you boot holding the Command-Option-P-R keys.
Hardware 2001-12-21
Retain Counts of io_object_t Objects in IOKit.framework (HTML) ()
QA1195: Distinguishes between the retain counts of an I/O Kit kernel object and its io_object_t user space proxy.
Hardware 2002-09-04
Sample code for allocating an amount of dictionary space (HTML)
HW71: Discusses the allocation and the setting of memory for Dictionary space in Open Firmware.
Hardware 1999-10-11
SCSI ID from vRefNum (HTML) ()
DV29: Legacy Mac OS technique for identifying the ID of a SCSI Parallel device containing a specified disk volume.
Hardware 1997-05-23
A SCSI little secret (HTML)
HW81: Details what to expect when accessing the motherboard SCSI bus on the Blue & White G3.
Hardware 1999-12-20
SCSIAction and IOSCSIUserClient on Mac OS X 10.2 (HTML) ()
QA1201: Describes migrating to a new API for SCSI Parallel devices starting with Mac OS X 10.2.
Hardware 2002-09-13
SDRAM Problems With Self-Powered USB Devices (HTML) ()
HW82: Alerts that non-compliant, self-powered USB devices plugged into a G4, can cause problems with low-voltage-sensitive SDRAM .
Hardware 2003-08-21
SDRAM, CAS Latency for the "Quicksilver" PowerMacG4s (HTML)
QA1071: Describes the supported CAS Latency values for the "QuickSilver", PowerMac G4 CPUs.
Hardware 2001-09-13
Sending SCSI commands to storage devices (HTML) ()
QA1179: Explains that Mac OS X does not implement SCSI pass-through for many mass storage devices.
Hardware 2002-08-06
Sequence Grabber - Determining the capture resolution of an IIDC device (HTML)
QA1403: Discusses how to determine the resolution of a captured image from an IIDC device
Hardware 2005-01-06
Sequence Grabber - Video capture with multiple IIDC cameras (HTML)
QA1365: Discusses factors which influence the number of IIDC cameras that can simultaniously be used for capture.
Hardware 2004-08-25
Serial API Choice (HTML)
DV39: Discusses the choice of serial APIs supported by traditional Mac OS and Mac OS X.
Hardware 2001-07-02
Sleep vs. Doze on Mac OS X (HTML)
QA1309: Discusses and demonstrates sleep versus doze detection on Machintosh Mac OS X
Hardware 2003-10-09
The state of mDNSResponder (HTML)
QA1339: Explains how to obtain information regarding the internal state of mDNSResponder.
Hardware 2004-02-06
Stopping Forth command scrolls (HTML) ()
HW57: Describes how to limit Forth commands from scrolling off the screen.
Hardware 1999-03-29
Switching between one and two machine mode for the Open Firmware user interface (HTML) ()
HW37: Explains how to change from one machine mode to two in the Open Firmware user interface.
Hardware 1999-02-15
T_DATA_REQ vs M_DATA TPI Message Blocks (HTML) ()
NW42: Explains why OT passes data to a TPI module using M_DATA message blocks instead of M_PROTO+T_DATA_REQ.
Hardware 1996-10-25
TCP/IP Option Sizes (HTML) ()
NW62: Enumerates the TCP/IP options and their sizes for Open Transport.
Hardware 1999-04-26
Timely Issues - 1904 (HTML) ()
OPS23: Explains why the beginning of the year 1904 was chosen for epoch of the Time global variable.
Hardware 1999-05-17
Tips on USB driver matching for Mac OS X (HTML)
QA1076: Gives some tips on getting USB driver matching to work.
Hardware 2001-10-02
Use the Doorbell (HTML) ()
Deprecated - FW01: Explains the function of the FireWire Serial Bus Protocol 2 (SBP2) doorbell.
Hardware 1999-05-17
Using "words" in Open Firmware (HTML)
HW73: Explains how to search for specific entries within all the global and local Open Firmware words.
Hardware 1999-10-11
Was that a path I just saw? (HTML)
HW101: Describes the Open Firmware path that is occasionally shown at boot time.
Hardware 2000-10-06
What are configuration variables in Open Firmware? (HTML) ()
HW38: Defines the configuration variables in Open Firmware.
Hardware 1999-02-15
What are generic names in Open Firmware? (HTML) ()
HW34: Documents the generic names in Open Firmware.
Hardware 1999-02-15
What are NewWorld and Open Firmware version 3? (HTML) ()
HW33: Describes "NewWorld project" and tells what part Open Firmware version 3 plays.
Hardware 1999-02-15
What are snag keys in Open Firmware? (HTML) ()
HW35: Explains Open Firmware snag keys, including examples of their function.
Hardware 1999-02-15
What is a CardBus host bus adapter HBA? (HTML)
HW79: Explains what a CardBus host bus adapter (HBA) is and discusses its implementation on the Macintosh.
Hardware 1999-11-15
What is a tokenizer? (HTML) ()
HW58: Defines a tokenizer.
Hardware 1999-03-29
What is an Open Firmware devalias? (HTML)
HW99: Describes devaliases in Open Firmware.
Hardware 2000-10-06
What is an Open Firmware phandle, and why can't I access it from the Mac OS? (HTML)
HW76: Explains an "Open Firmware phandle" and why it is inaccessible from the Mac OS.
Hardware 1999-11-15
What is meant by 1 machine mode verses 2 machine mode with respect to Open Firmware? (HTML) ()
HW36: Documents 1 machine mode vs. 2 machine mode in Open Firmware.
Hardware 1999-02-15
What is the "dump" word and how do I use it? (HTML)
HW68: Describes the function of the Open Firmware word "dump" and how it can be used.
Hardware 1999-10-11
What is the return stack in Open Firmware and can I use it? (HTML)
HW67: Describes the purpose of the Open Firmware return stack and how developers can use it.
Hardware 1999-10-11
What is the word "see" and how do I use it to help me find what a word does? (HTML)
HW72: Explains the function and use of the Open Firmware word "see".
Hardware 1999-10-11
What is unsolicited status? (HTML) ()
FW03: Explains the meaning and usage of the SBP-2 unsolicited status message.
Hardware 1999-05-17
What numeric base is the default for the Open Firmware user interface? (HTML)
HW65: Describes how the default numeric base used by the Open Firmware user interface is hexadecimal.
Hardware 1999-10-11
When to use PCMCIA, PC Card, and CardBus (HTML)
HW77: Explains the differences between PCMCIA, PC Card, and CardBus.
Hardware 1999-11-15
Which Machines Support Driver Services Library and the MP Nanokernel? (HTML) ()
HW63: Lists the systems that do and don't support the Driver Services Library and the MP Nanokernel.
Hardware 1999-07-12
Why did the name of the PCI bridge change? (HTML) ()
HW59: Explains the name change of the PCI bridge to the generic name "pci" in Open Firmware.
Hardware 1999-03-29
Why didn't I boot from the CD? (HTML)
HW98: Describes the behavior of holding down the "c" key at boot time.
Hardware 2000-10-06
Why does logging keep my Printer Module from working? (HTML) ()
Deprecated - QA1182: Describes some problems with standard printf logging in a Printer Module on Jaguar.
Hardware 2002-11-06