A computer housing or case contains computer system components including a display unit, a processor, and a computer power supply unit. One or more handles are positioned at a side of the case to allow a user to hold the encased computer system while viewing the display. A case has a support interface structure to hold the case steady in an upright position. The support interface structure of the case mates with a complimentary support interface in the weight-supporting base unit and mates with guides to align a power supply port in the case to contact a power supply port in the base unit. A base unit has a keyboard guide to receive a keyboard by lifting the keyboard above a support surface. A modular computer system comprises a tablet computer, a base unit, and a remote keyboard. A first infrared communication device couples the tablet computer to the remote keyboard and other input peripherals. A second infrared communication device couples the tablet computer to a remote printer. A radio frequency network adapter couples the tablet computer to the base unit, which provides additional communications to an external communications network.