1.4 time-sharing technology and time-sharing operating system
- The disadvantage of multi-batch system:
long 1. job processing time;
2. poor interaction;
3. Run uncertain process;
60's two major hardware development:
-
Technical interrupt
the CPU receives an external signal (interrupt signal), stop the current work, turn to deal with the external event, after processing back to the original work was interrupted (break) to continue their jobs. -
Technical channel
dedicated processor processing data transfer between peripherals and memory. -
Sharing operating system
emerged 1. transactional task of
highly interactive
fast response
2. Demands that supports multi-tasking / multi-user -
Multi-terminal computer
high performance plurality of host terminals +
hosts: operation, CPU + memory
terminals: input and display
- turn the host time-sharing technology service for each terminal, so that each terminal feel they are "exclusive" host.
- Time sharing
Concept: host for a short "time slice" as a unit, the CPU allocated to each terminal in turn used, until all jobs to be run to completion.
Since the very short time slice, in the case where a small number of terminals, each terminal can quickly regain the CPU, so that each terminal can obtain a timely response to
a wait period time slices * = the number of terminals.
- Characteristics sharing system
1 of the multiplexer (line use the same multi-user computer)
2. exclusive (exclusive computer users feel)
3. Interactive (responsive to user requests)
The practice of large-scale time-sharing systems:
* Mulltics Project
1962 by ARPA support, MIT, BELL, GE participation
MULTiplexed Information and Computing Service
- UNIX
first practical time-sharing operating system
to achieve the operating system portability
achieved hardware independence
introduced the concept of "special file" (Special File), and the file seen as peripheral, to achieve unified management of peripherals