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 Adaptec had years before produced PCMCIA parallel SCSI interfaces, but when PCMCIA was superseded by the ExpressCard Adaptec discontinued their PCMCIA line without supporting ExpressCard.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 port later than Windows 95/98 prevent user programs from directly writing to or reading from the LPT without additional software (kernel extensions). Current CNC Milling Machines also often make use of the parallel port to directly control the machine's motors and attachments. Traditionally IBM PC systems have allocated their first three parallel ports according to the configuration in the table below (if all three printer ports exist). If there is an unused slot, the port addresses of the others are moved up. (For example, if a port at 0x3BC does not exist, the port at 0x378 will then become the first