Very small, interpreter under 1, 800 lines, has no graphics. Topic of classic Addison-Wesley book 'A Little Smalltalk'. Both by Timothy Budd, Oregon State University. [Free for non-commercial use]
SET Language 2, close relative of SETL, has some clumsy support for closures, an experimental (broken) object system, and redefines integer division to mean something different than in SETL: 3/2 yields 1.5 in SETL, but only 1 in SETL2.