A computer architecture in which multiple processors share the same memory, which contains one copy of the operating system, one copy of any applications that are in use, and one copy of the data. Because the operating system divides the workload into tasks and assigns those tasks to whatever processors are available, SMP reduces transaction time. There are no glossary terms that begin with this letter. undo disk For Virtual Server and Virtual PC, a virtual hard disk that stores the changes made to a virtual machine's guest operating system and data after the Undo Disks feature has been enabled for the virtual machine. Changes accumulate in the undo disk (.vud) file until you commit or discard the changes. Each time you shut down or turn off a virtual machine, you decide whether to keep, commit, or discard the changes. See also: commit virtual DHCP server For Virtual Server, an emulation of a Dynamic Host Configuration Protocol (DHCP) server. A virtual network can be configured to provide a virtual DHCP server, which offers dynamic configuration of IP addresses and related information to DHCP-enabled virtual machines.