JTAG Tutorial

JTAG Tutorial 

Certain mobile phones have no other access capability other than a test interface to allow for debugging and memory analysis capability other than to use JTAG (Joint Test Action Group) standard: IEEE 1149.1 : 1990 Standard Test Access Port and Boundary-Scan Architecture. IEEE 1149.1 : 2001 is available here: http://standards.ieee.org/findstds/standard/1149.1-2001.html   

There are various reading materials available by way of the internet that help an examiner understand the way in which JTAG can be used: 

http://www.corelis.com/education/JTAG_Tutorial.htm

What is JTAG?
Overview of the JTAG architecture and the new technology trends that make using JTAG essential for dramatically reducing development and production costs. The article also describes the various uses of JTAG and the tools available today for supporting JTAG technology.

Additional material: http://en.wikipedia.org/wiki/Joint_Test_Action_Group

Other materials that may interest:

Mobile Phone Chip Off - http://trewmte.blogspot.com/2011/02/mobile-phone-chip-off.html 

Mobile device forensics - http://en.wikipedia.org/wiki/Mobile_device_forensics

JTAG acquisition from Android - http://www.caseite.com/content/jtag-acquisition-android

Is JTAG forensically approved? - http://www.forensicfocus.com/Forums/viewtopic/p=6533275/