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Review Question 1 of Introduction to Operating Systems

Consider a hypothetical 32-bit microprocessor that has 32-bit instructions composed of two fields. the first byte contains the opcode and theRemainder an immediate operand or an operand address.

  • What is the maximum directly addressable memory capacity (in bytes)?

2(32-8) = 16,777,216 bytes = 16 MB

  • Discuss the impact on the system speed if the microprocessor data bus has
  • a 32-bit local address bus and a 16-bit local data bus.

Instruction and data transfers would take three bus cycles each - one for the address and two for the data.

  • a 16-bit local address bus and a 16-bit local data bus.

Instruction and data transfers would take four bus cycles each - two for the address and two for the data.

  • How many bits are needed for the program counter and the instruction register?

24 bits for the PC (24-bit addresses), 32 bits for the IR (32-bit addresses)

In virtually all systems that include dma modules, dma access to main memory is given higher priority than processor access to main memory. why?

If a processor is held up in attempting to read or write memory, usually no damage occurs except a slight loss of time. However, aDMA transfer may be to or from a device that is receiving or sending data in a stream (e.g., disk or network), and cannot be stopped. Thus, if the DMA moduleis held up (denied continuing access to main memory), data will be lost.

Why does a batch system need memory protection? why does a multiprogrammed batch system need memory management and scheduling? why do bothTypes of systems need interrupts?

A batch system needs memory protection so that programs can't modify the monitor.

A multiprogrammed batch system needs memory management so that multiple jobs can be kept in memory at the same time. Memorymanagement will determine which portion of memory each job can use. The system also needs a scheduling algorithm to determine which job can run at any giventime.

Both types of systems need interrupts so that the operating system can regain control of the CPU. A batch system needs this totime-out a long job and a multiprogrammed system needs this to share the processor among the active processes.

What is the purpose of system calls, and how do system calls relate to the operating system and to the concept of dual-mode (kernel mode and userMode) operation?

With a time sharing system, the primary concern is turnaround time. A round-robin scheduler would given every process a chance torun on the CPU for a short time, and reduce the average turnaround time. If the scheduler instead let one job run until completion, then the first job wouldhave a short turnaround time, but later ones would have to wait for a long time.

In a batch system, the primary concern is throughput. In this case, the time spent switching between jobs is wasted, so a moreefficient scheduling algorithm would be first-come, first-served, and let each job run on the processor as long as it wants.

In ibm's mainframe operating system, os/390, one of the major modules in the kernel is the system resource manager (srm). this module isResponsible for the allocation of resources among address spaces (processes). the srm gives os/390 a degree of sophistication unique among operating systems.No other mainframe operating system, and certainly no other type of operating system, can match the functions performed by srm. the concept of resourceIncludes processor, real memory and i/o channels. srm accumulates statistics pertaining to utilization of processor, channel and various key data structures.Its purpose is to provide optimum performance based on performance monitoring and analysis. the installation sets forth various performance objectives, andThese serve as guidance to the srm, which dynamically modifies installation and job performance characteristics based on system utilization. in turn, the srmProvides reports that enable the trained operator to refine the configuration and parameter settings to improve user service.

This problem concerns one example of SRM activity. Real memory is divided into equal-sized blocks called frames, of which there maybe many thousands. Each frame can hold a block of virtual memory referred to as a page. SRM receives control approximately 20 times per second and inspects eachand every page frame. If the page has not been referenced or changed, a counter is incremented by 1. Over time, SRM averages these numbers to determine theaverage number of seconds that a page frame in the system goes untouched. What might be the purpose of this and what action might SRM take?

Questions & Answers

what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Operating systems. OpenStax CNX. Aug 13, 2009 Download for free at http://cnx.org/content/col10785/1.2
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