This document discusses multiprocessor and multicomputer systems. It defines multiprocessors as computer systems with multiple CPUs that share resources like memory, clock and I/O devices. Multiprocessor operating systems can be symmetric, with equal access for all CPUs, or master-slave with one CPU controlling others. Shared memory multiprocessors allow CPUs to access a common RAM while message passing multicomputers do not share memory between CPUs. Multiprocessor systems provide benefits like reliability, enhanced throughput and lower costs but require more complex operating systems and larger memory. Multicomputers are made up of separate computers while multiprocessors have multiple CPUs on a single motherboard sharing resources.

2. •
Objectives
•definition
•Multi processor operating systems
•Multiprocessor operating systems type
• Advantages of multiprocessor
•Disadvantages of multiprocessor
•Difference between multiprocessors and multicomputers

3. definition
• Most computer systems are single processor systems i.e they only
have one processor. However, multiprocessor or parallel systems are
increasing in importance nowadays. These systems have multiple
processors working in parallel that share the computer clock,
memory, bus, peripheral devices etc.

4. Multiprocessor operating systems
multiprocessor
multiprocessor multicomputer Distributed Systems
(a) Shared memory multiprocessor
(b) Message passing multicomputer
(c) Wide area distributed systems

5. Types of multiprocessors
Shared memory multiprocessor
A computer systems in which two or more cpus share full access to
acommon RAM .
The cpu can write some value into the memory and then read the word
back and get a different value .

6. multicomputer
• Definition
• Are tightly coupled cpus that do not share memory ( each one its has
memory ).
• These systems are also known by a variety of other names cluster
computer and cows ( cluster of workstation )

7. Multiprocessor operating systems types
•
Symmetric Multiprocessors
• In these types of systems, each processor contains a similar copy of the operating system
and they all communicate with each other. All the processors are in a peer to peer
relationship i.e. no master - slave relationship exists between them.
• An example of the symmetric multiprocessing system is the Encore version of Unix for
the Multimax Computer.
• If the two cpu simultaneously picking the same process to run the same memory page .
It associate a mutes(lock) with os .
• equal rights for all processors
• Any cpu can access or execute any process
• Each cpu has access to memory i/o devices or any other hardware .
• One operating system controls all cpu all cpu have equal rights

8. Multiprocessor operating systems types

9. Master-slave multiprocessors
• One is considered as master and other are slaves
• master cpu decides which cpu will perform which task or master executes system
programs and slaves are used for application programs .
• One processor interacts with i/o devices and other are used fpr increasing
processing
• There is one copy of the operating system and its table are present to cpu

10. Multiprocessor operating systems types
Each cpu it has its own operating systems
The memory divide into as many partition as there are cpus and give each cpu its own
private memory and its own private copy of operating systems

11. Multiprocessor operating systems types
•
Uniform memory access multiprocessor uma
(a) Without caching
(b) With caching
(c) With caching and private memory

12. Multiprocessor operating systems types
• Non Uniform memory access multiprocessor uma
• is a computer memory design used in multiprocessing, where the
memory access time depends on the memory location relative to the
processor.
• There is advisable address to all cpus
• Access to remote memory is via load and store instruction
• Acess to remote memory is slower than access to local memory

13. Advantages of Multiprocessor Systems
• More reliable Systems
• In a multiprocessor system, even if one processor fails, the system will
not halt. This ability to continue working despite hardware failure is
known as graceful degradation. For example: If there are 5 processors
in a multiprocessor system and one of them fails, then also 4
processors are still working. So the system only becomes slower and
does not ground to a halt.
•
Enhanced Throughput
• If multiple processors are working in tandem, then the throughput of
the system increases i.e. number of processes getting executed per
unit of time increase. If there are N processors then the throughput
increases by an amount just under N.

14. Advantages of Multiprocessor Systems
• More Economic Systems
•
Multiprocessor systems are cheaper than single processor systems in
the long run because they share the data storage, peripheral devices,
power supplies etc. If there are multiple processes that share data, it
is better to schedule them on multiprocessor systems with shared
data than have different computer systems with multiple copies of
the data.

15. Disadvantages of Multiprocessor Systems
• Increased Expense
• Even though multiprocessor systems are cheaper in the long run than
using multiple computer systems, still they are quite expensive. It is
much cheaper to buy a simple single processor system than a
multiprocessor system.
• Complicated Operating System Required
• There are multiple processors in a multiprocessor system that share
peripherals, memory etc. So, it is much more complicated to schedule
processes and impart resources to processes.than in single processor
systems. Hence, a more complex and complicated operating system is
required in multiprocessor systems.

16. Disadvantages of Multiprocessor Systems
• Large Main Memory Required
• All the processors in the multiprocessor system share the memory. So
a much larger pool of memory is required as compared to single
processor systems.

17. • Multiprocessor
• Amultiprocessor is simply
acomputer that has more than
one cpu on its motherboard .
• Multiprocessing is the use of
two or more centeral
processing units cpu with
asingle computer systems .
• Multiprocessor have asingle
physical address space
memory shared by all the cpus
• Amultiprocessor would run
slower because it would be in
one computer .
• Amultiprocessor is asingle
system with multiple cpu.
• multicomputer
• Acomputer made up of several
computers . Similar to parallel
computing .
• Distributed computing deals with
hardware and software systems
containing more than one
processing element multiple
programs running under aloosely
or tightly controlled regime .
• Multicomputer have one physical
address space per cpu .
• It can run faster
• Is multiple computers each of
which can have multiple processor
used for ture parallel processing