In June 1982 Columbia Data Products (CDP) of Columbia, Maryland, introduced the MPC 1600 "Multi Personal Computer," an exact functional copy of the IBM PC model 5150 except for the BIOS, which was developed by a "clean room" reverse engineering process, thus avoiding copyright infringement. IBM had published the bus and BIOS specifications, wrongly assuming that this would be enough to encourage the add-on market, and prevent unlicensed copying of the design.
"As the first IBM PC clone, the MPC was actually superior to the IBM original. It came with 128 KiB RAM standard, compared to the IBM's 64 KiB maximum. The MPC had eight PC expansion slots, with one filled by its video card. Its floppy disk drive interface was built into the motherboard. The IBM PC, in contrast, had only five expansion slots, with the video card and floppy disk controller taking two of them. The MPC also included two floppy disk drives, one parallel and two serial ports, which were all optional on the original IBM PC. The MPC was followed up with a portable PC, the 32 pound (15 kg) "luggable" Columbia VP in 1983" (Wikipedia article on Columbia Data Products, accessed 01-01-2013).