Wow, I hadn’t seen the OC8820 for decades! I used to code BASICA on it (or was it GW-BASIC)? back in the early 80s. If memory serves, it also came with CPM-80 in addition to MS-DOS. In addition to the BASIC interpreter, I remember the only apps available for it were SuperCalc (a Lotus 1-2-3 predecessor) and WordStar.