  We study the metastable response of a highly hysteretic DC-SQUID made of a
Niobium loop interrupted by two nano-bridges. We excite the SQUID with an
alternating current and with direct magnetic flux, and find different stability
zones forming diamond-like structures in the measured voltage across the SQUID.
When such a SQUID is embedded in a transmission line resonator similar diamond
structures are observed in the reflection pattern of the resonator. We have
calculated the DC-SQUID stability diagram in the plane of the exciting control
parameters, both analytically and numerically. In addition, we have obtained
numerical simulations of the SQUID equations of motion, taking into account
temperature variations and non-sinusoidal current-phase relation of the
nano-bridges. Good agreement is found between experimental and theoretical
results.
