Point of information: By and large FORTHs did not use bytecode. Execution tokens (XTs) were usually stored as a function of the default word size, which typically was 16 bits. There were some FORTHs that went out of their way to use token threading so they could store programs in byte codes, but those were pretty rare. Rarer still were programs that mixed byte code with word-sized code (although one such scheme is described in an issue of Forth Dimensions).