Without attempting to figure out whether this will fit the task, my mod of the BASIC52 interpreter, running on the Atmel AT89C51RD2/ED2, is a single-chip solution, as long as the on-chip RAM will be sufficient for the given task. The simplest setup is the 'RD2 itself, crystal, power source, reset circuit and an RS232 transceiver - I usually wire up such on a solder-devboard ("stripboard") in a hour or so, plus locating the parts in the drawer... ;-)
It is now compatible with the Elector version ("1.3") as long as the extensions are concerned, so the I2C-extension from there can be used if needed.

JW