TABLE 1. Glossary

LFSR

Linear Feedback Shift Register. When enabled, will generate a 16-bit signature of sampled serial test

data.

LSP

Local Scan Port. A four signal port that drives a local (i.e. non-backplane) scan chain. (e.g., TCK

TDO

Local

Local is used to describe IEEE Std. 1149.1 compliant scan rings and the SCANSTA111 Test Access Port

that drives them. The term local was adopted from the system test architecture that the ’STA111 will most

commonly be used in; namely, a system test backplane with a ’STA111 on each card driving up to 3 local

scan rings per card. (Each card can contain multiple ’STA111s, with 3 local scan ports per ’STA111.)

Park/Unpark/Unparked Parked, unpark, and unparked, are used to describe the state of the LSP controller and the state of the

local TAP controllers (the local TAP controllers refers to the TAP controllers of the scan components that

make up a local scan ring). Park is also used to describe the action of parking a LSP (transitioning into

one of the Parked LSP controller states). It is important to understand that when a LSP controller is in

one of the parked states, TMS

given state.

TAP

Test Access Port as defined by IEEE Std. 1149.1.

Selected/Unselected

Selected and Unselected refers to the state of the ’STA111 Selection Controller. A selected ’STA111 has

been properly addressed and is ready to receive Level 2 protocol. Unselected ’STA111s monitor the

system test backplane, but do not accept Level 2 protocol (except for the GOTOWAIT instruction). The

data registers and LSPs of unselected ’STA111s are not accessible from the system test master.

Active Scan Chain

The Active Scan Chain refers to the scan chain configuration as seen by the test master at a given

moment. When a ’STA111 is selected with all of its LSPs parked, the active scan chain is the current

scan register only. When a LSP is unparked, the active scan chain becomes: TDI

register

→ the local scan ring registers → a PAD bit → TDO

configurations of the LSP network.

Level 1 Protocol

Level 1 is the protocol used to address a ’STA111.

Level 2 Protocol

Level 2 is the protocol that is used once a ’STA111 is selected. Level 2 protocol is IEEE Std. 1149.1

compliant when an individual ’STA111 is selected.

PAD

A one bit register that is placed at the end of each local scan port scan-chain. The PAD bit eliminates the

prop delay that would be added by the ’STA111 LSPN logic between TDI

buffering and synchronizing the LSP TDI inputs to the falling edge of TCK

scanned at higher frequencies without violating set-up and hold times.

LSB

Least Significant Bit, the right-most position in a register (bit 0).

MSB

Most Significant Bit, the left-most position in a register.

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