Reference: Okuno, H.; Osato, N.; & Takeuchi, I. Firmware Approach to Fast Lisp Interpreter. ACM, 1987.
Abstract: The approach to speed up a Lisp interpreter by implementing it in firmware seems promising. A microcoded Lisp interpreter shows good performance for very simple benchmarks, while it often fails to provide good performance for larger benchmarks and applications unless speedup techniques are devised for it. This was the case for the TAO/ELIS system. This paper describes various techniques devised for the TAO/ELIS system in order to speed up the interpreter of the TAO language implemented on the ELIS Lisp machine. The techniques include data type dispatch, variable access function call and so on. TAO is not only upward compatible with Common Lisp, but also incorporates logic programming, object-oriented programming and Fortran/C-like programming into Lisp programming. TAO also provides concurrent programming and supports multiple users (up to eight users). The TAO interpreter for those programming paradigms is coded fully in microcodes. In spite of rich functionalities, the speed of interpreted codes of TAO is comparable to that of compiled codes of commercial Lisp machines. Furthermore, the speeds of the interpreted codes of the same program written in various programming paradigms in TAO does not differ so much. This speed balance is very important for the user. Another outstanding feature of the TAO/ELIS system is its firmware development environments. Micro Assembler and Linker are written in TAO, which enables the user to use the capability of TAO in microcodes. Since debugging tools are also written in a mini-Lisp, many new tools were developed in parallel to debugging of microcodes. This high level approach to firmware development environments is very important to provide high productivity of development.