  We have studied the performance of two different types of front-end systems
for our gamma camera based on Hamamatsu H8500 (flat-panel 64 channels
multi-anode PSPMT) with a CsI(Tl) scintillator array. The array consists of 64
pixels of $6\times6\times20{\rm mm}^3$ which corresponds to the anode pixels of
H8500. One of the system is based on commercial ASIC chips in order to readout
every anode. The others are based on resistive charge divider network between
anodes to reduce readout channels. In both systems, each pixel (6mm) was
clearly resolved by flood field irradiation of $^{137}$Cs. We also investigated
the energy resolution of these systems and showed the performance of the
cascade connection of resistive network between some PMTs for large area
detectors.
