THE

THE is a multiprogramming system. The goal is to process smoothly a continuous flow of user programs.

1. Reduce turn-around time for progress of short duration.
2. Econimic user of peripheral devices.
3. Automatic control of backing store.
4. Ability to run large flexible user programs that can communicate with each other.

Notify: This is not multi-user operating system.

System Structure

• Core memory <=> Main Memory, Unit: Core page
• Drum <=> Secondary storage (disk), Unit: Drum Page
• Segment <=> Virtual pages

Sequential Process

A society of sequential process

• Process per program
• Process per peripheral
• Process for segment controller and message interpretation Mutual synchronization is necessary and possible.

  Hierarchy

Level 0: processor virtulization

Level 1: Memory virtualization

Level 2: Console I/O virtualization

Level 3: All other I/O virtualization

Level 4: User programs

Level 5: Operator (Joke!)

ADV Debugging can be done layer by layer DIS Need to avoid cyclic dependency with careful design; Crossing layers will add overhead

Semaphore

Synchronization, PV operations. (First time in history)