Abstract. Integrated circuit cards or smart cards are now well-known. Applications such as electronic purses (cash units stored in cards), subscriber identification cards used in cellular telephone or access keys for pay-TV and information highways emerge in many places with millions of users. More services are required by applications providers and card holders. Mainly, new integrated circuit cards evolve towards non-predefined multi-purpose, open and multi-user applications. Today, operating systems implemented into integrated circuit cards cannot respond to these new trends. They have evolved from simple operating systems defining an hardware abstraction level up to file management systems or database management systems where the card behaviour was defined once at the manufacturing level or by the card issuer. The needs for open and flexible card life cycle enabling to accommodate executable code loaded by different service providers require a new generation of smart cards. Operating systems based on object-oriented technologies are key components for future integrated circuit cards applications.

Squeak is an open, highly-portable Smalltalk implementation whose virtual machine is written entirely in Smalltalk, making it easy to debug, analyze, and change. To achieve practical performance, a translator produces an equivalent C program whose performance is comparable to commercial Smalltalks. Other noteworthy aspects of Squeak include: 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 bulkmutation of objects; extensions of BitBlt to handle color of any depth and anti-aliased image rotation and scaling; and real-time sound and music synthesis written entirely in Smalltalk. Overview Squeak is a modern implementation of Smalltalk-80 that is available for free via the Internet, at

We present techniques for eliminating dispatch overhead in a virtual machine interpreter using a lightweight just-in-time native-code compilation. In the context of the Tcl VM, we convert bytecodes to native Sparc code, by concatenating the native instructions used by the VM to implement each bytecode instruction. We thus eliminate the dispatch loop. Furthermore, immediate arguments of bytecode instructions are substituted into the native code using runtime specialization. Native code output from the C compiler is not amenable to relocation by copying; fix-up of the code is required for correct execution. The dynamic instruction count improvement from eliding dispatch depends on the length in native instructions of each bytecode opcode implementation. These are relatively long in Tcl, but dispatch is still a significant overhead. However, their length also causes our technique to overflow the instruction cache. Furthermore, our native compilation consumes runtime. Some benchmarks run up to three times faster, but roughly half slow down, or exhibit little change.