A multi-language, time-sharing system (MTS-12) has been developed for the PDP-12, a Digital Equipment Corporation laboratory computer. This low-cost, core-resident system features program storage on LINC tape (3/4" magnetic tape on a 4" reel), access to the high-level interpreted FOCAL language, and a special variable storage in the user buffer area which permits string handling, answer storage and other housekeeping functions. Although less convenient than special purpose languages, FOCAL has direct command capability which is easy to learn and which provides full mathematical support. No specific author mode is available, but FOCAL is quite simple and can be used without programer assistance. A MODIFY command provides online program correction, and file protection is available to control use of this feature. With this system, sophisticated teaching programs can be presented to three simultaneous users in only 12k of 12 bit core. The system is expandable, but is especially suited for small-scale use with the mainframe unattended, when the PDP-12 might not be in use. (Author)