PCMCIA
When the PC Card was introduced, the only other way to connect peripherals to a laptop computer was via RS-232 and parallel ports of limited performance, so it was widely adopted for many peripherals. More recently, virtually all laptop equipment has 480 Mbit/s Hi-Speed USB 2.0 ports, and most types of peripheral which formerly used a PC Card connection are available for USB or are built-in, making the ExpressCard less necessary than the PC Card was in its day. Some laptop computers do not have an ExpressCard slot.