Problems associated with the application of the connectivity approach to computer system security are addressed. The failure of trusted connectivity to protect computer systems is indicated. The work is presented in the form of a humorous allegory.

This paper describes ASSIST-V, a software tool designed for use in the teaching of operating systems, fie management, and machine architecture courses. ASSIST-V is a program that provides an environment for the implementation, testing, and evaluation of systems software for the IBM 360 series machines. This capability is achieved by simulating all relevant aspects of the machine's architecture. In particular, ASSIST-V simulates interrupts, I/O channels, and I/O devices, as well as all IBM 360 machine instructions. In addition, ASSIST-V provides extensive debugging and statistics-gathering aids.

This paper describes a compiler called ORACLE which allows a student to examine the actions performed by a simple compiler. Two features are provided to assist the student. The first called replacement mode, provides the necessary conditions to simulate the replacement of three compiler components: symbol table management, lexical analysis, and syntax analysis. Each replacement module is monitored by ORACLE in order to detect errors and to verify correct operation. The second, a trace option, permits source statements to initiate or terminate a selective monitoring of the actions of the compiler.

The problem of reducing the number of states in an arbitrary incompletely specified deterministic finite-state machine to k states (for a given k) has proven intractible to solution within "reasonable" time; most techniques seem to require exponential time. Two reduction techniques–state assignment to the DON'T CARE entries, and so-called "state splitting"–are investigated. For both of the techniques, the question, "Can I achieve an equivalent k state machine?" is shown to be polynomial complete, with the resulting conjecture that neither is solvable in time bounded by a polynomial function of the size of the machine.