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Mainframe System
Large computer system that provides computing services to a "
community of users through remotely connected terminals"
Goals of early mainframes:
Reduce setup time by batching similar jobs.
Automatic job sequencing – automatically transfers
control from one job to another.
Resident monitor
  initial control in monitor
  control transfers to job
  when job completes control transfers back to monitor
Operating System Concepts with Java !
Batch processing operating system
Punch cards for a job in
batch processing
operating system
Operating System Concepts with Java !
History of Operating Systems: batch processing
Early batch system
  bring cards to 1401
  read cards to tape
  put tape on 7094 which does computing
  put tape on 1401 which prints output
Operating System Concepts with Java !
Evolution of Operating Systems
Time Sharing
Operating System Concepts with Java !
Batch Systems
Memory protection for monitor
•  while the user program is executing, it must not alter the memory area
containing the monitor
•  prevents a job from monopolizing the system
Privileged instructions
•  can only be executed by the monitor
•  gives OS more flexibility in controlling user programs
Operating System Concepts with Java !
Simple Batch System Overhead
Processor time alternates between execution of user
programs and execution of the monitor
some main memory is now given over to the monitor
some processor time is consumed by the monitor
Despite overhead, the simple batch system improves
utilization of the computer
Operating System Concepts with Java !
Multiprogrammed Batch Systems
Processor is
often idle
even with
  I/O devices
are slow
Operating System Concepts with Java !
The processor spends a certain amount
of time executing, until it reaches an I/O
instruction; it must then wait until that I/O
instruction concludes before proceeding
Operating System Concepts with Java !
There must be enough memory to hold the OS (resident
monitor) and one user program
When one job needs to wait for I/O, the processor can switch
to the other job, which is likely not waiting for I/O
Operating System Concepts with Java !
  also known as multitasking
  memory is expanded to hold three, four, or more
programs and switch among all of them
Operating System Concepts with Java !
Multiprogramming Example
Operating System Concepts with Java !
Effects on Resource Utilization
Table 2.2
Operating System Concepts with Java !
Effects of Multiprogramming on Resource Utilization
Utilization Histograms
Operating System Concepts with Java !
Can be used to handle multiple interactive jobs
Processor time is shared among multiple users
Multiple users simultaneously access the system
through terminals, with the OS interleaving the
execution of each user program in a short burst or
quantum of computation
Operating System Concepts with Java !
Operating System Concepts with Java !
Memory Layout for a Simple Batch System
Operating System Concepts with Java !
Multiprogrammed Batch Systems
Several jobs are kept in main memory at the same time, and the "
CPU is multiplexed among them. "
Operating System Concepts with Java !
Multi-programming by sharing CPU
CPU time is still wasted to wait for I/O
Operating System Concepts with Java !
Use of Buffering to Save CPU-time
Overlap the I/O of one job with its own computation
Operating System Concepts with Java !
Mainframe computer
in 1967
Modern Mainframe Computer
IBM System/360 Mainframe Computer
Operating System Concepts with Java !
OS Features Needed for Multiprogramming
I/O routine supplied by the system.
Memory management – the system must
allocate the memory to several jobs.
CPU scheduling – the system must choose
among several jobs ready to run.
Device allocation- which I/O to be used by
which job.
Operating System Concepts with Java !
Concurrency in Multiprogramming
Systems that are designed to concurrently execute more than
one task
Operating System Concepts with Java !
Time-Sharing Systems: Interactive Computing
CPU is multiplexed among several jobs that are kept in
memory and on disk.
Job swaps in and out of memory to the disk.
On-line communication between the user and the system
  When the operating system finishes the execution of
one command, it seeks the next “control statement”
from the user’s keyboard.
On-line access to data and code system must be able to
provide data and code to the user.
Operating System Concepts with Java !
Timesharing (multitasking)
Systems that allow multiple users (programs) to run concurrently.
The system switches from one user to another.
Operating System Concepts with Java !
Desktop Systems
Personal computers – computer system dedicated to a single
user; PC appeared in the 1970s. Computer usability is the main
I/O devices – keyboards, mice, display screens, small printers.
User convenience and responsiveness.
Technology for larger operating system can be adopted.
Single user. Often individuals have sole use of computer and do
not need advanced CPU utilization or protection features.
Different types of operating systems, Windows, MacOS, UNIX,
Operating System Concepts with Java !
Desktop computers
Apple PowerMac G5!
Operating System Concepts with Java !
Parallel Systems
Multiprocessor systems with more than one CPU in close
Tightly coupled system – processors share memory and a clock;
communication usually takes place through the shared memory.
Advantages of parallel system:
  Increased throughput
  Economical
  Increased reliability
  Graceful degradation
  Tandem systems
The APE/Quadrics is a massively parallel computer
containing up to 2048 processor elements (PEs). Its design is SIMD (Single Instruction Multiple Data) principle
Every PE executes the same instruction simultaneously.
Operating System Concepts with Java !
IBM project manager shows off Blue Gene/L, the world's fastest computer, which set the record in IBM's Rochester facility.
Steve Conway, works for Seattle-based Cray, Inc., indirectly a successor to Cray Research, the Twin Cities firm that dominated the supercomputer industry in the 1970s and '80s.
Karl Feind of Silicon Graphics says there were smiles, high fives, awe, and relief, when
an SGI machine, developed partly in Minnesota, captured the speed title last October.
Operating System Concepts with Java !