KMD - 16k seems to be a very fancy advanced RTOS to me. The OM-55 Navy SatCom modem used 32k for the entire program and had 16k, with spare space, for RAM. This involved a full multi-tasking (time sliced) operating system - on an 8080. (They cost $100 a pop when it was designed.) The kernel portion was under 1k. The IO routines were small. The rest involved maintaining the DSCS satellite communications protocols running, demodulating the data, and feeding it all to the output while running the modest control panel.
edit: By the way Philbrick is in my engineering DNA. I started designing professionally in about '65 - as in getting real pay for it. And the first job or two involved operational amplifiers with these new fangled RA-909's.