modern Smalltalk variants. After significant revisions which froze some aspects of execution semantics to gain performance (by adopting a Simula-like class inheritance model of execution), Smalltalk-76 was created. This system had a development environment featuring most of the now familiar tools, including a class library code browser/editor. Smalltalk-80 added metaclasses, to help maintain the "everything is an object" (except variables) paradigm by associating properties and behavior with individual classes, and even primitives such as integer and boolean values (for example, to support different ways to create instances). Smalltalk-80 was the first language variant made available outside of PARC, first as Smalltalk-80 Version 1, being given to a small number of firms (Hewlett-Packard, Apple Computer, Tektronix, and Digital Equipment Corporation (DEC)) and universities (UC Berkeley) for peer review and implementing on their platforms. Later, in 1983, a general availability implementation, named Smalltalk-80 Version 2, was released as an image (platform-independent file with object definitions) and a virtual machine specification. ANSI Smalltalk has been the standard language reference since 1998. Two currently popular Smalltalk implementation variants are descendants of those original Smalltalk-80 images. Squeak is an open source implementation derived from Smalltalk-80 Version 1 by way of Apple Smalltalk. VisualWorks is derived from Smalltalk-80 version 2 by way of Smalltalk-80 2.5 and ObjectWorks (both products of ParcPlace Systems, a Xerox PARC spin-off company formed to bring Smalltalk to the market). As an interesting link between generations, in 2001 Vassili Bykov implemented Hobbes, a virtual machine running Smalltalk-80 inside VisualWorks. (Dan Ingalls later ported Hobbes to Squeak.) During the late 1980s to mid-1990s, Smalltalk environments—including support, training and add-ons—were sold by two competing organizations: ParcPlace Systems and Digitalk, both California based. ParcPlace Systems tended to focus on the Unix/Sun microsystems market, while Digitalk focused on Intel-based PCs running Microsoft Windows or IBM's OS/2. Both firms struggled to take Smalltalk mainstream due to Smalltalk's substantial memory needs, limited run-time performance, and initial lack of supported connectivity to SQL-based relational database servers. While the high price of ParcPlace Smalltalk limited its market penetration to mid-sized and large commercial organizations, the Digitalk products initially tried to reach a wider audience with a lower price. IBM initially supported the Digitalk product, but then entered the market with a Smalltalk product in 1995 called VisualAge/Smalltalk. Easel introduced Enfin at this time on Windows and OS/2. Enfin became far more popular in Europe, as IBM introduced it into IT