Operating System Concepts2.

M.C.A  -  Operating  System Short Questions.  G.VeeraRaghavaiah

51.Address Space:- Operating system creates multiple address spaces (memory for processor to run in ) out of the memory and allocates them to processes. It accomplishes the space multiplexing the processor.

52. File System:- By implementing the file system and I/O system so that processes can easily use and share the disks. It accomplishes this by space multiplexing the disks and the time multiplexing I/O channels.

53.H/W Interface:- This H/W interface consists of things like program counter, registers , interrupts ,disks, terminals. H/W interface consists of everything . You need to know about the H/W in order to write programs  that will execute on the H/W.

54.H/W Resource:- Operating system manages the resource of the computer system  are

                              Processor, Memory, I/O controllers, Disk Devices and other Devices.

55.Mechanism:- A Mechanism is a set of basic facilities that can be used in different ways. Ex :PL is a mechanism to write the programs.

56.OS  Interface:- OS shares the characteristics of the H/W and S/W. An OS is a software that is it is a  program that is compiled , linked, and run on a computer .

57. Policy:- A Policy is a mechanism for particular purpose. Ex: Program to solve the specific Equation.

58. Process:- OS creates several  processes out the single processor and allocates them to programs. It accomplishes by time multiplexing the processor.

59.Resource Management:-  As a resource manager  OS performs the operations.

                                                          1)Transforming

                                                          2)Multiplexing

                                                          3)Scheduling

60. Space Division Multiplexing:- A resource is divided in to smaller versions  of itself and each virtual computer is given a part of the resource.

61.Space Sharing:- Space division multiplexing is used in Multiplexing primary and secondary storage (memory & discs)  is called Space Sharing.

62. Spooling:- Simultaneous peripheral operations online. Two or more  virtual computers can issue printer operations.

63.System Call:-  In process execution .In return for the instructions that allow the virtual processor to request virtual resources from  the OS. These instructions are called system calls. System calls allow a programmer to 1) Create new virtual computers, 2) Communicates with other virtual computers 3) Allocates the memory as needed  4) Do some I/O 5) Access a sophisticated file system.

64.Time Division Multiplexing:- Here the resource is used for different virtual computers at different times.

65.Time Sharing:- In  many of the contexts time division multiplexing is called Time sharing i.e., allocates processor time to the jobs that are writing in priority Queue on the basis of time sharing manner.

66.Transformation:- OS transform physical resources into virtual resources to avoid the difficulties associated with using H/W resources.

67.Virtual Computer :- OS creates what we will call  virtual computers from the physical  computers. The first thing is we need to look at how virtual computer differs from actual physical computers. The most significant difference is that there are more virtual computers only one physical computer.

68.Virtual Resources:- A virtual resource provides the essential functionality of the H/W resources, But is easily to use the cause details of H/W interface are hidden .

69.ASM Block:-  A Block of memory that can be allotted permanently to some group of instructions. These instructions memory addresses cannot change in RAM. In C++ compiler you use ASM Block of executing  instructions.

70. Base Register:-  The memory base register is added to all addresses when the system is in user  mode.

71. Bound  Register :- The memory bound register is the addresses limit . In user mode all addresses  must be less than the boundary register. Otherwise a program error interrupt will occur. The comparison is done before the base register is added.

72. Control Register:- Hole values that control the execution of the processor. The control registers are all 32-bits long.

73.C.P.U:- The CPU provides 32 general purpose registers are referenced  using the names R0 through R31 as is common  with RISC machines.

74.General Purpose Registers:- CPU provides 32 general purpose registers each 32-bits long. These are the registers R0 to R31.

                         R0=Always 0 value.

                         R1=Procedure returns

                         R31=Procedure returns addresses

                         R8, R9, R10, R11=System calls

                         R29=Frame pointer

                         R30=Stack pointer

75.I/O Addresses Space:- The I/O addresses space is part of actual memory at addresses 0 to on FFFFFF. The I/O addresses space is a part of physical addresses space reserved for I/O devices and consist of the physical addresses on F0000000 to on FFFFFFFF.

76.Interrupt:- An Interrupt is an immediately transfer of control caused by an event in the system.

77.Interrupt Vector Area:- When an Interrupt will occur the processor then saves the  ia register in the iia register, gets the addresses of the interrupt handler by locking in  the appropriate slot  in the interrupt vector area.

78. Logical addresses :- Processor is in user mode.

79.Physical Address:- Processor is in  system mode.

80.Logical Addresses space:- Processor is in user mode all the addresses are generated by a program.

81.Physical Addresses Space:-   Processor is in the system mode, all the addresses are generated by a program.

82. Masked :- Some interrupts can only occur if bit-1 of PSW register is 1. If it is 0 the interrupts are masked.

83.Memory Addresses space:-  The memory addresses space is a part of the physical addresses  space where we can place the physical memory.

84. Memory Mapped I/O:- Meaning that communication between I/O devices and the processor is done through physical memory locations, in the I/O addresses space.

85.Processor:- CPU processor consists of 32-bit general purpose registers for processed the program instructions and data.

86.User Mode:- If the system is in the user mode PSW bit-0 is set to 1. In system mode PSW bit-0 is set to 0.

87.System Mode:- If the system is in the system mode PSW  bit-0 is set to 0. If the system is in system mode we cannot interact with OS. If the system is we can interact with OS.

88. Int Create Process(Int block number, Int no. of blocks):- Create a new processor and returns process id . The processor code and data are  on disc in  a “No. of blocks in consequent order starting with disc block block number. –1 returns process was not created there were no process descriptor in process table.

89.Void Exit Process(Int Exit Code):- The calling  process was terminated and its resources are returned to OS. This system call always succeeds.

90.Int Create Message Queue(Void):- A new message queue is created and is its identifiers is return. A return code of –1 means that the message queue table was fill and the message queue was not created.