By means of a trip down virtualization history, I found a real gem in 1969 paper called A program simulator by partial interpretation, by Kazuhiro Fuchi, Hozumi Tanaka, Yuriko Manago, Toshitsugu Yuba of the Japanese Government Electrotechnical Laboratory. It was published at the second symposium on Operating systems principles (SOSP) in 1969. It describes a system where regular target instructions are directly interpreted, and any privileged instructions are trapped and simulated. Very similar to how VmWare does it for x86, or any other modern virtualization solution.
The interesting bit is really the uses that this system is put to:
In promoting the ETSS project a program simulator based on an idea of partial interpretation has been constructed, and its principle and design are described in the paper. This new approach has been introduced to provide the simulator with such features as high speed and high accuracy in simulation and simplification in implementation. The essence of the idea of partial interpretation is using direct execution of instructions by hardware and simulation of them by an interpreter in combination, wherewith the hardware interrupt mechanism intermediates the two phases of the whole simulation. An interruption takes place when executing a “privileged” instruction, which triggers the simulation of the instruction. The other type of instructions are normally rendered to direct execution by hardware. The simulation method for devices operating in parallel is also described with respect to the timing control and scheduling. A program simulator of this type provides a powerful tool for debugging “supervisor ” programs and opens a new approach to system expansion.
Note that last part. This is essentially a virtual machine used for operating-system debug. So far, the earliest mention of this idea that I have found. There are similar ideas in a classic 1972 IBM paper. If anyone has seen anything older, please comment and tell me!
It is also fun reading these old papers… they are usually scanned from a paper copy, and therefore really show how papers looked and felt forty years ago. Long before desktop publishing, or even TeX.