Parallel SCSI data rate of 640 MB/s. Due to the technical constraints of a parallel bus system, SCSI has since evolved into faster serial interfaces, mainly Serial Attached SCSI and Fibre Channel. The iSCSI protocol doesn't even have a physical definition at all but uses any IP network, usually based on Ethernet. , SCSI interfaces had become impossible to find for laptop computers. Adaptec had years before produced PCMCIA parallel SCSI interfaces, but when PCMCIA was superseded by the ExpressCard Adaptec discontinued their PCMCIA line without supporting ExpressCard. Ratoc produced USB and Firewire to parallel SCSI adaptors, but ceased production when the
Parallel algorithm wall, and thus multicore systems have become more widespread, making parallel algorithms of more general use. The cost or complexity of serial algorithms is estimated in terms of the space (memory) and time (processor cycles) that they take. Parallel algorithms need to optimize one more resource, the communication between different processors. There are two ways parallel processors communicate, shared memory or message passing. Shared memory processing needs additional locking for the data, imposes the overhead of additional processor and bus cycles, and also serializes some portion of the algorithm. Message passing processing uses channels and message boxes but this communication