IBM PC 5150 with no drives?

Light pen interface was built in on the video board. Both CGA and MDP (Monochrome Display and Printer) boards had it. But IBM didn't sell a light pen, largely because the long persistence phosphor of the IBM monochrome monitor made it unusable. Clock and calendar were not on the motherboard until the AT. MS-DOS would ask for DATE and TIME unless you had an AUTOEXEC.BAT file. Unless you told it otherwise, it assumed that the date was 1/1/80. Multifunction cards with disk controller, or video came much later. (~85) The remaining "functions" to fill out the claimed numbers were software in the box. Usually a RAM disk program and a print spooler. Thus, a typical "SIX function" muyltifunction board would consist of Clock/calendar, memory, serial, parallel, and two programs.