The IBM Portable Personal Computer 5155, introduced February 1984. Intel 8088 4.77MHz CPU (like original PC and XT). It had built-in ROM Basic, two 5.25" 360K half-height floppy diskette drives (the second one optional) , no hard disk, 256K memory standard (expandable to 640K), a small (9-inch) 25x80 character monochrome amber screen capable of graphics, and DOS. The keyboard folds up and snaps shut, and can also be detached. Weight: about 30 pounds. It came with a nice dark-blue carrying case, kind of an IBM suitcase. Price: $2900. For at least a year or two the Columbia Business School required all students to have one of these.