Prototype Logic Board Offers Rare Look at the iPhone’s Simple Origins

An anonymous source has offered a rare look at what it says is an original iPhone development board, a prototype with the code name M68.

The Verge today published photographs of a prototype logic board that Apple engineers used to create the original iPhone way back in 2007. While the company would later move on to much smaller test boards for subsequent iPhone models, these never-before-seen images offer an interesting look back at the development of the iconic handset.

The original prototype, known as an engineering validation test (EVT), is a development device in which components are arranged on an oversized PC-style motherboard, allowing for easy replacement if components need to be changed or tweaked:

Apple was focused on surprising everyone with the iPhone, and that meant that many of the engineers working on the original handset didn’t even know what it would eventually look like.

To achieve that level of secrecy, Apple created special prototype development boards that contained nearly all of the iPhone’s parts, spread out across a large circuit board. The Verge has obtained exclusive access to the original iPhone M68 prototype board from 2006 / 2007, thanks to Red M Sixty, a source that asked to remain anonymous. It’s the first time this board has been pictured publicly, and it provides a rare historical look at an important part of computing history, showing how Apple developed the original iPhone.

Since the prototype board was to be used for development purposes, it contained everything that a developer could ask for. There’s a serial connector that could be used to test iPod accessories. The prototype also had two mini USB ports which provided engineers with access to the Samsung AP and the radio. While the board also has a SIM card slot, Apple included an RJ11 port that allowed developers to connect a landline and test voice calls on it:

There’s a serial connector at the top that was used to test iPod accessories since the iPhone also used Apple’s 30-pin connector, and there’s even a LAN port for connectivity. Two Mini USB connectors flank the side of the board, which were used by engineers to access the main iPhone application processor and radio (baseband). Apple engineers could use these Mini USB ports to code for the device without ever seeing the screen […]

To the right of the radio board, you’ll see an RJ11 port, which is the same registered jack that’s used by regular landline phones. Apple used this so that engineers could plug a regular landline phone headset into this iPhone development board and test voice calls […]

This particular prototype unit even includes a screen, though some other prototypes lacked a display. Instead, they featured a component video and RCA connectors on the board which allowed developers to plug it into a display. The board is also filled with JTAG connectors and white connectors with pins that could be used by engineers for low-level debugging:

Elsewhere on this board, you’ll see lots of white connectors with pins. The smaller ones are JTAG connectors used for low-level debugging. Engineers could connect signal probes to some of these connectors to monitor various signals and voltages, allowing developers to test key software changes to the iPhone and make sure they weren’t negatively impacting the hardware […]

If an engineer inside Apple received a development board like this without a screen, component video and RCA connectors on the side of the board could be used to connect it to a display. Engineers could also test headphone connectivity, thanks to stereo line out ports on the side.

Now, Apple uses security shields for iPhone prototypes, but this early development board is certainly a fascinating look at Apple secrecy leading up to the introduction of the iPhone.

The Verge‘s full article is a worthwhile read.