THE System
System was composed as a set of sequential processes.
Each peforms a sequential computation.
Processes communicate through explicit synchronization statements.
Each process could be tested and verified independently.
Each level sees a logical machine provided by lower levels.
- level 2 sees virtual processors
- level 3 sees VM (really segments)
- level 4 sees a “virtual console”
- level 5 sees “virtual” I/O drivers