In this paper, we study and build the Hamiltonian system attached to any
gl2β(C) rational connection with arbitrary number of
non-ramified poles of arbitrary degrees. In particular, we propose the Lax
pairs expressed in terms of irregular times associated to the poles and a map
reducing the space of irregular times to isomonodromic times. We apply the
general theory to all cases where the associated spectral curve has genus 1 and
recover the standard Painlev\'{e} equations. We finally make the connection
with the topological recursion and the quantization of classical spectral curve
from this perspective.Comment: 67 pages + appendice