The NEC PC-6000 Series was a series of 8-bit home computers introduced in November 1981 by NEC Home Electronics (NEC-HE). There were several models in this series, such as the PC-6001, the PC-6001 MK2 and the PC-6001 MK2 SR. There was also an American version, called the NEC TREK, or NEC PC-6001A. It was followed by the PC-6600 Series.
Several peripherals were available for the system in North America, including an expander with three cartridge jacks (some of the cartridge-based games used two cartridges), a cassette-tape recorder, a 5.25" floppy disk drive, a printer, and a touchpad.
Source: Wikipedia, "PC-6000 series", available under the CC-BY-SA License.