SYMBOL hardware debugging facilities
M. A. Calhoun · 1971
The SYMBOL system is a full-scale working demonstration of an ALGOL-like, high-level, general-purpose, procedural language and a multi-processing, multi-programming operating system implemented directly in hardware. The results have proven the versatility of the design, construction, and testing techniques that were developed to enable a small number of people to implement such a major system in a reasonable time and at a relatively low cost.