Many boards have engineering curcuits embedded on PCB,but not used by customers. But they have great value for reverse engineers, and hardware debug engineers.

Decided to make special thread for posting regarding data.



Debug XDP for Intel P55 PCH mesanine 60-pin connector on Intel DP55DK board.

Also reference PCI-Express NVIDIA videocards often have JTAG connector onboard.

On 8800GTS 640MB G80-chip based videocard:



J9 connector pattern on GeForce GTX 285 (G200 based) videocard:



J502 connector pattern on GeForce 7600GT (G73 based) videocard:



All of them are the same. Will post JTAG signal pinouts after reverse engineering.

JTAG adapter for standard LPT port.

This exact one is ALTERA ByteBlaster MV, but it's not complex to make it suitable not only for ALTERA's.

offtopic...
Since it is English language thread, pleas sory me for my grammar.
Whot kind of abilitys we reach due to using JTAG? Software voltmods? Disabled GPU units unlocing?

Hardware-level debugging, code tracing, boundary-scan testing, acessing BGA chip I/O, flashing onboard NVrams.
It's not indended for customer, and needs advanced tools both with engineering confidential software usually.

Foxconn 865 chipset motherboard for Socket 478 CPU's, HDT connector nearby CPU socket.



ASUS P5B Deluxe iP965 chipset motherboard JTAG connector, under bottom layer of mask. Also near CPU socket