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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

Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
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.
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.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
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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