A mainframe computer is disclosed including a hardware platform (10) with hardware resources comprising processors and memory. The computer comprises a virtualization hypervisor software of the market (300). Thus, an instance (1) of a proprietary Mainframe software environment can run on the hardware architecture, in at least one first virtual machine that can run on the virtualization hypervisor. In order to guarantee the security/reliability and the performance of the mainframe computer, the virtualization hypervisor is configured so as to create a hardware resource pool (100) of the hardware platform that is dedicated to hosting, exclusively, the one (or more) virtual machine(s) in which an instance of the proprietary Mainframe software environment is running.