Jtag testing of buses using plug-in cards with Jtag logic mounted thereon

摘要

A plug-in JTAG test card includes JTAG boundary scan circuitry which may be used to drive JTAG test data out onto portions of buses connected to peripheral plug-in slots. One or more of the JTAG plug-in test cards can be used to verify the integrity of each of the point-to- point connections on the buses which terminate in the peripheral plug-in slots. In one advantageous embodiment, the plug-in JTAG test cards simulate a dual in-line memory module (DIMM) or single in-line memory module (SIMM) cards which include scan test buffer circuitry but do not actually include memory chips so that an inexpensive plug-in card can be used to provide JTAG testing at the manufacturing level for multiple motherboards. In a particularly preferred embodiment, JTAG boundary scan buffer circuits, such as, for example, SN74ABT8245's, are used as test circuits rather than for their intended use as interface circuits.