Squeak 3.9

Squeak is an open, highly-portable Smalltalk-80 implementation whose virtual machine is written entirely in Smalltalk, making it easy to debug, analyze, and change.
The image above was created in Squeak, and illustrates several of Squeaks abilities, including the ability to scale and rotate bitmap images at any color depth, anti-aliased TrueType fonts and vector graphics.
Main features:
- real-time sound and music synthesis written entirely in Smalltalk
- extensions of BitBlt to handle color of any depth and anti-aliased image rotation and scaling
- network access support that allows simple construction of servers and other useful facilities
- it runs bit-identical on many platforms (Windows, Mac, Unix, and others)
- a compact object format that typically requires only a single word of overhead per object
- a simple yet efficient incremental garbage collector for 32-bit direct pointers
- efficient bulk-mutation of objects .