A virtual machine needs four core resources: CPU, memory, network, and storage (disk). These resources are granted to the virtual machine through the configuration of the virtual hardware.
When a virtual machine is created, a default set of virtual hardware is assigned to it. VMware provides devices and resources that can be added and configured to the virtual machine. Not all virtual hardware devices will be available to every single virtual machine; both the physical hardware of the ESXi host and the VM's guest OS must support these configurations. For example, a virtual machine will not be capable of being configured with more vCPUs than the ESXi host has CPU sockets.
The virtual hardware available includes:
BIOS: Phoenix Technologies 6.00 that functions like a physical server BIOS. Virtual machine administrators are able to enable/disable I/O devices, configure boot order, and so on.
DVD/CD-ROM: NEC VMware IDE CDR10 that is installed by default...