A Mac booted in Target Mode can be attached to the port of any other computer, Mac or PC, where it will appear as an external device. Hard drives within the target Mac, for example, can be formatted or partitioned exactly like any other external drive. Some computers will also make their internal CD/DVD drives and other internal and external peripheral hardware available to the host computer.[2]
Target Disk Mode is useful for accessing the contents of a Mac which cannot load its own operating system. Target Disk Mode is the preferred form of old-computer to new-computer interconnect used by Apple's Migration Assistant. Migration Assistant supports Ethernet (wired) or Wi-Fi, which TDM does not. Neither supports USB; however, Thunderbolt-to-Firewire, Thunderbolt-to-Gigabit-Ethernet, and USB-3.0-to-Gigabit-Ethernet adapters are an option when one of the computers does not have Firewire or Thunderbolt.
History
Apple introduced disk mode access with the original PowerBook 100 and continued to offer it with most subsequent PowerBook series and FireWire-equipped Macs. As long as the requisite software appeared in the system ROM, the Mac could be booted into disk mode.
Target Disk Mode was originally called SCSI Disk Mode, and a special cable (SCSI System Cable) allowed the original PowerBook series to attach to a desktop Mac as an external SCSI disk. A unique system control panel on the PowerBook was used to select a non-conflicting SCSI ID number from the host Mac. This also made it possible to select the disk in the Startup control panel and boot up from it.
With the change to IDE drives starting with the PowerBook 150 and 190, Apple implemented HD Target Mode, which essentially enabled SCSI Disk Mode by translating the external SCSI commands via the ATAdriver. Officially reserved for Apple's portables only, the mode was supported by all PowerBooks except the 140, 145, 145B, 150 and 170. However, SCSI Disk Mode can be implemented unofficially on any Macintosh with an external SCSI port by suspending the startup process with the interrupt switch, as long as all internal drives on the chain can be set to different IDs than the active host system's devices.
When Apple dropped the SCSI interface, starting with the AGP Power Mac G4 and “Pismo” PowerBook G3, FireWire Target Disk mode replaced the earlier disk mode implementation, also receiving official support beyond laptops to all subsequent Macs with built-in Firewire.
The 12-inch Retina MacBook (early 2015) has only one expansion port, a USB-C port that supports charging, external displays, and Target Disk Mode. Using Target Disk Mode on this MacBook requires a cable that supports USB 3.0 or USB 3.1, with either a USB-A or USB-C connector on one end and a USB-C connector on the other end for the MacBook.[5]
The host computer (the computer into which the Target Disk Mode booted computer is plugged) merely needs to meet the same requirements as for any external mass storage device using the bus in question, and (if access to native Mac formatted partitions such as the boot volume is desired) support for the correct version of Hierarchical File System. On Classic Mac OS, this means FireWire 2.3.3 or later and Mac OS 8.6 or later are required to use a Firewire target.[1]
The host computer may run Microsoft Windows, but with some possible shortcomings: to read a Mac's HFS-formatted partitions, extra drivers such as MacDrive, TransMac, MacDisk, or HFSExplorer are necessary. Users also must ensure their computer possesses appropriate interface hardware in order to physically connect to a Mac in Target Mode. MacDrive also has a read-only option to prevent any accidental editing of the computer in Target Disk Mode; however, this mode cannot be set after an HFS/HFS+ disk is mounted. With the addition of HFS drivers into Apple's Boot Camp, it has also become possible for Macs running Windows to read (but not write) HFS partitions, without the purchase of software. Users have separated these drivers from the main Bootcamp install, and now also install on other Windows computers. Host computers running Linux are also able to read and write to a Mac's HFS or HFS+ formatted devices through Target Disk Mode. It is working out-of-the-box on most distributions as HFS+ support is part of the Linux kernel. However these filesystems cannot be checked for errors, so for shrinking or moving partitions it is preferred to use Mac OS.
Small Computer System Interface is a set of standards for physically connecting and transferring data between computers and peripheral devices, best known for its use with storage devices such as hard disk drives. SCSI was introduced in the 1980s and has seen widespread use on servers and high-end workstations, with new SCSI standards being published as recently as SAS-4 in 2017.
AirPort is a discontinued line of wireless routers and network cards developed by Apple Inc. using Wi-Fi protocols. In Japan, the line of products was marketed under the brand AirMac due to previous registration by I-O Data.
The Macintosh Plus computer is the third model in the Macintosh line, introduced on January 16, 1986, two years after the original Macintosh and a little more than a year after the Macintosh 512K, with a price tag of US$2,599. As an evolutionary improvement over the 512K, it shipped with 1 MB of RAM standard, expandable to 4 MB, and an external SCSI peripheral bus, among smaller improvements. Originally, the computer's case was the same beige color as the original Macintosh, Pantone 453; however, in 1987, the case color was changed to the long-lived, warm gray "Platinum" color. It is the earliest Macintosh model able to run System Software 5, System 6, and System 7, up to System 7.5.5, but not System 7.5.2.
The Power Macintosh G3 is a series of personal computers designed, manufactured, and sold by Apple Computer from November 1997 to August 1999. It represented Apple's first step towards eliminating redundancy and complexity in the product line by replacing eight Power Macintosh models with three: Desktop and Mini Tower models for professional and home use, and an All-In-One model for education. The introduction of the Desktop and Mini Tower models coincided with Apple starting to sell build-to-order Macs directly from its web site in an online store, which was unusual for the time as Dell was the only major computer manufacturer doing this. Apple's move to build-to-order sales of the Power Macintosh G3 also coincided with the acquisition of Power Computing Corporation, which had been providing telephone sales of Macintosh clones for more than two years.
SuperDrive is the product name for a floppy disk drive and later an optical disc drive made and marketed by Apple Inc. The name was initially used for what Apple called their high-density floppy disk drive, and later for the internal CD and DVD drive integrated with Apple computers. Though Apple no longer manufactures computers that feature built-in SuperDrives, the name is still used when referring to Apple's external CD and DVD drive accessory (pictured).
Apple Inc. sold a variety of LCD and CRT computer displays in the past. Apple paused production of their own standalone displays in 2016 and partnered with LG to design displays for Macs. In June 2019, the Pro Display XDR was introduced, however it was expensive and targeted for professionals. Nearly three years later, in March 2022, the Studio Display was launched as a consumer-targeted counterpart to the professional monitor. These two are currently the only Apple-branded displays available.
Pegasos is a MicroATX motherboard powered by a PowerPC 750CXe or PowerPC 7447 microprocessor, featuring three PCI slots, one AGP slot, two Ethernet ports, USB, DDR, AC'97 sound, and FireWire. Like the PowerPC Macintosh counterparts, it boots via Open Firmware.
New World ROM computers are Macintosh models that do not use a Macintosh Toolbox ROM on the logic board. Due to Mac OS X not requiring the availability of the Toolbox, this allowed ROM sizes to shrink dramatically, and facilitated the use of flash memory for system firmware instead of the now more expensive and less flexible Mask ROM that most previous Macs used. A facility for loading the Toolbox from the startup device was, however, made available, allowing the use of Mac OS 8 and Mac OS 9 on New World machines.
Old World ROM computers are the Macintosh (Mac) models that use a Macintosh Toolbox read-only memory (ROM) chip, usually in a socket. All Macs prior to the iMac, the iBook, the Blue and White Power Mac G3 and the Bronze Keyboard (Lombard) PowerBook G3 use Old World ROM, while said models, as well as all subsequent models until the introduction of the Intel-based EFI Models, are New World ROM machines. In particular, the Beige Power Mac G3 and all other beige and platinum-colored Power Macs are Old World ROM machines. In common use, the "Old World" designation usually applies to the early generations of PCI-based "beige" Power Macs, but not the older Motorola 68000-based Macs; however, the Toolbox runs the same way on all three types of machines.
A disk enclosure is a specialized casing designed to hold and power hard disk drives or solid state drives while providing a mechanism to allow them to communicate to one or more separate computers.
The USB mass storage device class is a set of computing communications protocols, specifically a USB Device Class, defined by the USB Implementers Forum that makes a USB device accessible to a host computing device and enables file transfers between the host and the USB device. To a host, the USB device acts as an external hard drive; the protocol set interfaces with a number of storage devices.
LaCie is an American-French computer hardware company specializing in external hard drives, RAID arrays, optical drives, Flash Drives, and computer monitors. The company markets several lines of hard drives with a capacity of up to many terabytes of data, with a choice of interfaces. LaCie also has a series of mobile bus-powered hard drives.
Apple Partition Map (APM) is a partition scheme used to define the low-level organization of data on disks formatted for use with 68k and PowerPC Macintosh computers. It was introduced with the Macintosh II.
The PowerBook 3400c is a laptop computer in the PowerBook line manufactured by Apple Computer from February to November 1997. It was briefly the fastest laptop in the world. Using the PowerPC 603e processor running at speeds of up to 240 MHz, this PowerBook was the first to feature a PCI architecture, EDO memory, and a 64-bit wide, 40 MHz internal bus. It was also the first PowerBook to feature a PC card slot capable of being used as a zoomed video port. Like all Apple laptops since the PowerBook 500 series, it featured a built-in trackpad as the pointing device.
Boot Camp Assistant is a multi boot utility included with Apple Inc.'s macOS that assists users in installing Microsoft Windows operating systems on Intel-based Macintosh computers. The utility guides users through non-destructive disk partitioning of their hard disk drive or solid-state drive and installation of Windows device drivers for the Apple hardware. The utility also installs a Windows Control Panel applet for selecting the default boot operating system.
A live USB is a portable USB-attached external data storage device containing a full operating system that can be booted from. The term is reminiscent of USB flash drives but may encompass an external hard disk drive or solid-state drive, though they may be referred to as "live HDD" and "live SSD" respectively. They are the evolutionary next step after live CDs, but with the added benefit of writable storage, allowing customizations to the booted operating system. Live USBs can be used in embedded systems for system administration, data recovery, or test driving, and can persistently save settings and install software packages on the USB device.
SanDisk Professional is a brand of Western Digital that produces external storage products designed and marketed for the Macintosh, creative pro, photography and A/V markets. Its USB, FireWire, eSATA, SAS, SCSI Thunderbolt, and Fibre Channel systems support all levels of audio/video production.
Thunderbolt is the brand name of a hardware interface for the connection of external peripherals to a computer. It has been developed by Intel, in collaboration with Apple. It was initially marketed under the name Light Peak, and first sold as part of an end-user product on 24 February 2011.
IEEE 1394 is an interface standard for a serial bus for high-speed communications and isochronous real-time data transfer. It was developed in the late 1980s and early 1990s by Apple in cooperation with a number of companies, primarily Sony and Panasonic. It is most commonly known by the name FireWire (Apple), though other brand names exist such as i.LINK (Sony), and Lynx.
In computing, Linux-IO (LIO) Target is an open-source implementation of the SCSI target that has become the standard one included in the Linux kernel. Internally, LIO does not initiate sessions, but instead provides one or more Logical Unit Numbers (LUNs), waits for SCSI commands from a SCSI initiator, and performs required input/output data transfers. LIO supports common storage fabrics, including FCoE, Fibre Channel, IEEE 1394, iSCSI, iSCSI Extensions for RDMA (iSER), SCSI RDMA Protocol (SRP) and USB. It is included in most Linux distributions; native support for LIO in QEMU/KVM, libvirt, and OpenStack makes LIO also a storage option for cloud deployments.
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