Interactive TV/arcade games have been entertaining people for over 50 years. Nowadays a large number of legacy TV/arcade games have been ported to new platforms such as PCs by emulation. However, they generally require that the players be co-located to interact with one computer that emulates the game. This paper proposes a novel approach to turning those single-computer games into multicomputer games such that multiple players can play their favorite legacy games in real time over a computer network. The main challenge in this work is how to synchronize multiple replicas of a game without semantic knowledge about or modifications to the game. We present the approach, especially the synchronization algorithm, and evaluate its effectiveness under a variety of network conditions. In future research we will extend this work on mobile devices.

Collaborative technology plays an important role in pervasive computing environment and there are more and more multi-user applications for people to use. However, AutoCAD, as a powerful tool for CAD(Computer Aided Design), still lacks efficient interactive functions. This paper will present CoAutoCAD which makes AutoCAD collaborative from its implementation and application aspects. Three important layers of CoAutoCAD Kernel are shown as Coadapter, Coordinator and Engine. Coadapter layer can get user commands through the API offered by AutoCAD; Coordinator layer deliver messages among users in P2P environments; Engine layer is based on Mark & Retrace algorithm to make collaboration reliable. According to its implementation, CoAutoCAD has some features. The adaptation from AutoCAD is transparent for users and it does not need the source code ofAutoCAD. CoAutoCAD can have the functions which AutoCAD has and these two tools are compatible. Users send their messages directly to each other and the collaboration ofCoAutoCAD is efficient.