Serial port ports with pinouts and voltage levels incompatible with RS-232. Inter-operation with RS-232 devices may be impossible as the serial port cannot withstand the voltage levels produced and may have other differences that "lock in" the user to products of a particular manufacturer. Low-cost processors now allow higher-speed, but more complex, serial communication standards such as USB and FireWire to replace RS-232. These make it possible to connect devices that would not have operated feasibly over slower serial connections, such as mass storage, sound, and video devices. Many personal computer motherboards still have at least one serial port, even if accessible
NAS Parallel Benchmarks serial versions of the benchmarks consistent with the parallel versions and defined a problem size "Class W" for small-memory systems. NPB 2.4 of 2002 offered a new MPI implementation and introduced another still larger problem size "Class D". It also augmented one benchmark with I/O-intensive subtypes. NPB 3 retained the MPI implementation from NPB 2 and came in more flavors, namely OpenMP, Java and High Performance Fortran. These new parallel implementations were derived from the serial codes in NPB 2.3 with additional optimizations. NPB 3.1 and NPB 3.2 added three more benchmarks, which, however, were not available across all implementations;