JTAG 101: IEE 1149.x and Software Debug
JTAG (jay-tag) is one of the engineering acronyms that have been transformed into a noun, although arguably it is not so popular as RAM, or CPU. IEEE Std 1149.1-1990 IEEE Standard Test Access Port and Boundary-Scan Architecture is the official name, but JTAG is a bit snappier and is an abbreviation of Joint Test Action Group.
<br>If you examine the standard’s title you may be able to deduce the two use cases for JTAG devices and hardware. This paper deals with using the Test Access Port (TAP) as a means to control the execution of the processor, and to debug software via the TAP.
Not content with JTAG or IEE1149.1 as a name for this feature, most semiconductor vendors have also declared their own brand name version. To help a user migrate to IA32, this white paper gives a quick overview of the various implementations, and names, of JTAG debug methods for users familiar with PowerPC, ARM and MIPS processors and this is compared to the JTAG implementation in the Intel® Atom™ microprocessor.
Read the full JTAG 101: IEE 1149.x and Software Debug White Paper.