Smalltalk runs on a virtual machine VM -- an abstract computer -- that can be implemented on various platforms. A Smalltalk program is translated for this abstract computer and is independent from the target platform. Because the virtual machine also offers the platform resources in an abstracted way, a Smalltalk program is executable on all platforms with a compatible virtual machine. The virtual machine technology can be traced back to Peter Ladin's SECD machine for LISP that was designed in the early 60s. In 1983, the Smalltalk group at PARC added the JIT (just-in-time compilation) technology of the virtual machine from Smalltalk so that it is capable of running efficiently on commercial computers (on a Motorola 68020 system). It was the first implementation of an implicitly typed and dynamic compiled system with late-binding.
The concept of a virtual machine and the pure object orientation of Smalltalk allows the automatic organisation of the object memory. For this purpoe, the Smalltalk VM has the so-called garbage collector which automatically and efficiently recognises objects that are no longer used and re-uses the memory that they used up. 'Generation scavenging', the first ever performing algorithm for the memory organisation was first implemented in Berkley Smalltalk and then installed into the second generation of virtual machines by the company ParcPlace Systems. This architecture is still used today in VisualWorks.
There is a saying: "Smalltalk started it all". Smalltalk was the first consequential object oriented language (and the second language with OO elements after Simula, by which the OO concept was invented). Smalltalk was the origin or catalyst for the present day workstations, the mouse operation, windows system, interactive development environments and many technologies such as VM and GC that are clearly used by Java and C# today. All of this is historically interesting and can be read in the following sources:
"THE EARLY HISTORY OF SMALLTALK" by Alan C. Kay, in History of Programming
Languages, Thomas J. Bergin and Richard G. Gibson, Eds. Addison-Wesley, ISBN 0-201-89502-1.
"The Community of Smalltalk" by Adele Goldberg, in Handbook of Programming
Languages, Vol. 1. Object-Oriented Programming Languages, Peter H Salus, Ed. McMillan, ISBN 1-57870-008-6.
Adele Goldberg presents Smalltalk-80.
The enthusiasm for Smalltalk cannot be explained. Instead, it lies in the inner qualities of Smalltalk and its environment.
Smalltalk was developed at Xerox Palo Alto Research Center in the 70s and 80s. The language was designed to combine comprehension with expressiveness and flexibility. The usage at local schools helped in creating a system that was responsive (children quickly grow impatient) and at the same time fun to use (otherwise, the children would not have used it).
In 1988, Parcplace System was founded by Xerox to commercially exploit Smalltalk. Parcplace Systems merged with Digitalk, becoming Parcplace-Digitalk in 1995 and was renamed to ObjectShare in 1997. In 1999, the VisualWorks technology was bought up by Cincom. In doing so, Cincom took over the entire engineering team and forced a more considerable evolution and implementation of newer technologies from the internet environment.