Developer Transition Kit (2005)



The 2005 Developer Transition Kit (DTK), also known as the Developer Transition System (DTS), is an Intel Mac made available for lease to developers enrolled in an Apple Developer Connection subscription. Announced at the WWDC 2005 keynote on 2005, the DTK was leased to developers for US$999, with Apple offering a first-generation Intel iMac in exchange for returning the machine within a week of a 2006 deadline.

As with the Apple TV (1st generation), the DTK makes use of a platform that was never used on a retail Mac. Specifically, it uses the Intel Pentium 4 "Prescott" platform, based on the abandoned NetBurst microarchitecture, while the first retail Macs use the Core Duo "Yonah" platform, based on the Core microarchitecture.

Hardware

 * CPU Specs:
 * Core Design: Intel "Prescott" Pentium 4 660 x 1
 * CPU Speed: 3.6 GHz
 * Chipset:
 * Northbridge: Intel 915G with Intel GMA 900 GPU
 * Southbridge: Intel ICH6 82801FB
 * Front-side Bus Speed: 800 MHz
 * DVI-D video output via Silicon Image ORION ADD2-N PCI Express adapter
 * RAM: 1 GiB 533 MHz DDR2 ECC SDRAM
 * Storage: 160 GB
 * Firmware: Developer builds of Mac OS X 10.4
 * Initial firmware: 10.4.1 (8B1025)
 * Last firmware: 10.4.3 (8F1111)
 * Internal Name:

Software
DTK machines used beta releases branched from stable builds of Mac OS X Tiger, which at the time was publicly released for PowerPC Macs. The machines shipped with Mac OS X 10.4.1 (8B1025) preinstalled, along with a DVD to reinstall this build. Apple later released updated builds on the Apple Developer Connection portal for DTK lessors, in compressed DMG format. These could be burnt to a DVD-R/DVD-RW using Disk Utility. The DVD includes Xcode 2.1.

As Software Update was not yet functional in the 10.4.1 build, updating the machine was only possible by manually downloading a full DVD image.

The first public Mac OS X build for Intel was 10.4.4 (8G1165), however it was only provided on DVD media specific to Mac models it initially shipped with. Mac OS X Leopard was the first full upgrade release for Intel Macs.

Release notes below are Intel-specific changes made on top of those for the public releases of Tiger they are based on. They are compiled from user-written recounts of the release notes, rather than official Apple documentation.

PC Similarities
The hardware of the DTK is notable for being extremely similar to a traditional x86-based PC of the time. The logic board is not an Apple design - it is a modified Intel Desktop Board D915GUXLK, with a BIOS build customised to meet Apple's requirements, and rear I/O connectors intended to fit the unmodified late 2005 Power Mac G5 case. This is not uncommon, as Intel's Desktop Boards division acted as an ODM for major PC brands. An anonymous Intel employee describes that the motherboard "was just another OEM-specific prototype based on a production board to them" (Intel), and that the project had no references to Apple internally. The logic board has "Barracuda" printed between the CPU and RAM slots, where an Intel model number would usually appear - likely the codename Intel gave this specific motherboard adaptation. The original codename for the D915GUX series is "Luxembourg" (the "UX" suffix is derived from the codename).

A backplate has been installed to adapt the Power Mac G5's logic board screw mounting points to the standard microATX form factor, and the Power Mac G5 power supply is adapted to the standard ATX power supply 24-pin and 4-pin connectors using a daughterboard with Apple part number 920-0267-03. Unlike retail Mac Pros, which exclusively use PCI Express, the DTK logic board provides one PCI Express x16 and one x1 slot, and two legacy PCI slots. The logic board identifies itself as "Apple Computer Inc. Apple Development Platform" with model number AAD16649-103, and BIOS version string EV91510A.86X.0450, dated 2005. The "EV91510A" prefix, and the format of the entire version string, match Intel's retail 915 chipset-based motherboards.

While the machine uses the Intel 915G chipset's integrated Intel GMA 900 GPU, no video output is present on the logic board itself. A PCI Express card provides the video output functionality. This works around the lack of onboard video output connector on the unchanged Power Mac G5 case. The card in question is an off-the-shelf Advanced Digital Display 2 card manufactured by Silicon Image, based on the Sil1364 chipset. ADD2 is an Intel proprietary extension of PCI Express, supported by Intel 9xx, G/Q3x, and G/Q4x chipsets, whose original purpose is to expose the additional video outputs of Intel GMA chipsets on PCs with limited video outputs directly on the motherboard.

The machine uses the legacy Master Boot Record scheme, rather than the GPT and Extensible Firmware Interface (EFI) scheme used by shipping Intel Macs. The reason for this is likely a combination of Intel lacking a stable implementation of EFI for their motherboards at the time, and Apple not wanting significant changes made to the BIOS to ensure the project remained secret. This makes it possible to install any other x86 operating system, such as Windows.

Influence on Hackintoshing
The DTK, and subsequent online leaks of its restore DVD images, prompted the creation of the "Hackintosh" movement, also referred to as "OSx86", which produces tools and patches enabling macOS to successfully boot on non-Apple hardware, and make use of hardware components not supported by the set of drivers built into the operating system. The osx86project.org website was registered on 2005 to hold documentation and forum discussions (since moved to insanelymac.org) on installing the DTK builds of Mac OS X Tiger.

The DTK features an Infineon Trusted Platform Module (TPM), required for the machine to successfully boot into Mac OS X, to prevent straightforward installation of the DTK's Mac OS X builds onto similar non-Apple hardware. The security check is implemented in the Rosetta emulation layer, which allows PowerPC apps to seamlessly run on an Intel Mac. Should the TPM challenges fail, Rosetta refuses to start. A critical Mac OS X component, ATSServer (Apple Type System daemon), is included as a PowerPC-only binary, thereby requiring the TPM check to pass for Mac OS X to boot into a graphical interface. Cracked releases of the Mac OS X builds patch out the TPM requirement, allowing it to be installed on similar non-Apple hardware with a "Prescott" Pentium 4 and Intel 915G chipset. Further patches developed by the community enable it to run on a wider range of platforms, such as Intel Pentium M and AMD Athlon 64, by working around the use of SSE3 instructions in Rosetta.

Source code to the Darwin/x86 bootloader (also known by its build system version, Boot-132) was released by Apple, and is used as the basis for Hackintosh bootloaders such as Chameleon.

While some retail Macs shipped with TPM hardware, the operating system did not make use of it, and subsequent Macs removed the TPM. Retail Intel Macs instead use the System Management Controller and Dont Steal Mac OS.kext (DSMOS) to implement a hardware check that occurs earlier in the boot process.