Question

Ex. 1.5 -What is the role of the magic number for binary executable files? Where is it stored? Ex. 1.6- List all segments that consist an address space and explain each segment. Ex. 1.8-What are von-Neumann machines, and how are they related to the computers we use today?

Answer 1

Ex 1.5 The format of every binary file is defined in either a.out or exec in standard include directory #include<a.out.h> or #include<exec.h>. These files have magic number stored in front of the file and tells operating system whether the file is a binary or of other type. The linux command file uses the magic number in a file to decipher the type of file.

Ex. 1.6 Address space is that memory area consisting of all addresses for devices and files. Or in other words sometimes it is defines as scope of physical and virtual addresses accessible to processor. In computer each device and process is allocated addresses which is further some portion of processor address space. The addresses are further separated by segments or offsets . When we add this offsets are added your program is referred to secondary addresses.The address space consists both physical memory and virtual memory.

Ex. 1.8 Von Neumann :is an computer based architecture that describes computer unit consisting of following components

a). ALU Unit

b). Memory Unit

c). Control Unit

All kept inside CPU and except to this Two more units with Input and Output.

Here control unit contains instruction register and program counter

where instruction registers keeps necessary details relevant to you program means the instructions needed in a program. The program counter is sort of PCB which kept the processes in a queue so that processor may pick the next processes from the queue.

Memory unit is used to store the data and the instructions.

Limitation of this architecture is that at the same time it is difficult to run data operation and memory fetch

whereas new technology beats the old one with its capabilities like

a). higher performance

b). better silicon utilization

c). less power consumption

d). better price/performance