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An integrity check of the BS chains requires a description of the BS architecture present in the BS components present (obtainable from the SN74BCT8244 data sheet), and information concerning their location in the board-level BS chain. These two types of information are merged in table 1 below.

Parameter Component 0 Component 1 Component 2
Component belongs to BS chain 0 0 1
Location of the component in the chain 0 1 0
Length of the Instruction Register (IR) 8 8 8
Contents of the IR following capture XXXXXX01 XXXXXX01 XXXXXX01
Is an Identification Register present? No No No
Sample / Preload code 00000010 00000010 00000010

Table 1: Information required for checking the integrity of the BS chains.

Notice that only that information which is not pre-defined is required, such as the code of the S/P mandatory instruction, or the length of the instruction register and its contents following a Capture-IR operation (the two bits closest to TDO are pre-defined, but the remaining bits might be used to capture relevant information).