A given interconnect of a programmable gate array includes a programmable repeater circuit that enables selective isolation and testing of a select block of configured circuitry within the programmable gate array. The programmable repeater circuit includes an input node coupled to a first portion of the given interconnect and an output node coupled to a second portion of the given interconnect. A selective buffer circuit selectively outputs a buffered output signal to the output node that is related to a logic state at the input node. A signal storage circuit is also connected to the input node for selectively storing the logic state received from the input node. In a further embodiment, the signal storage circuit comprises an LSSD register. A primary latch of the LSSD register receives data selectively either from the input node, in accordance with a first clock signal, or alternatively from a secondary serial input node, in accordance with a second clock signal. A secondary latch of the LSSD register is selectively coupled, per a third clock signal, to receive and latch therein latched data of the primary latch. Data representative of data latched within the secondary latch is provided at a secondary serial output, and selectively provided at the primary output node when enabled per a programmable enable signal. In yet a further embodiment, the LSSD register is part of a serial scan chain for selectively interfacing an interconnect boundary of the select block of the configured circuitry within the programmable gate array.