Interested to Buy Any Domain ? << Click Here >> for more details...
what is a far pointer
- 12 Answers
- 39164 Views
- ABB, DRDO, ITI, Maruti Suzuki, Steel Plant, TCS, Toyota, Vivo Mobiles, I also Faced
- E-Mail Answers
Answer Posted / lalit kumar
Far pointers have a size of 4 bytes. They store both the
segment and the offset of the address the pointer is
referencing. A far pointer has an address range of 0 - 1M
bytes. It is important to understand that an addressing
range of 1M does not remove the 640K barrier from the
program. It means that the pointer can address the upper
memory area (641 - 1M) which typically contains video
memory, ROM and anything else that may be loaded high.
1: A far pointer can be incremented and decremented using
arithmetic operators. When a far pointer is incremented or
decremented ONLY the offset of the pointer is actually
incremented or decremented. The segment is never incremented
by the arithmetic operators. This means that although a far
pointer can address up to 1Mb of memory, it can only be
incremented through 64Kb and the offset will start at zero
again without changing the value of the segment. This is
referred to as "wrapping" the pointer
(e.g. 0F3E:FFFF + 1 = 0F3E:0000).
2:When a far pointer is decremented from zero it will wrap
the other way and become 64K.
3:Far pointers are not unique. It is possible to have two
far memory addresses that have different segments values and
different offset values that address the same memory
location e.g. 0777:2222 has an absolute address of
07770 + 2222 = 09992 and 0999:0002 has an absolute address
of 09990 + 0002 = 09992. When relational operators are used
on far pointers only the offsets are compared. For example:
if we let a = 0777:2222 and let b = 0999:0002 then a == b
would return false because this is equivalent to 2222 ==
0002 which is in fact false. In other words relational
operators will only work on far pointers if the segment
values of the pointers being compared are the same.
| Is This Answer Correct ? | 3 Yes | 5 No |
Post New Answer View All Answers
Why c is called top down?
What is the sizeof () a pointer?
When should volatile modifier be used?
Devise a program that inputs a 3 digit number n and finds out whether the number is prime or not. Find out its factors.
int i=3; this declaration tells the C compiler to a) reserve space in memory to hold the integer value b) associate the name i with this memory location c) store the value 3 at this location d) all the above
Can a pointer be static?
What is the use of #define preprocessor in c?
A SIMPLE PROGRAM OF GRAPHICS AND THEIR OUTPUT I WANT SEE WAHAT OUTOUT OF GRAPHICS PROGRAM
Wt are the Buses in C Language
What is #line in c?
What is extern keyword in c?
Explain the difference between strcpy() and memcpy() function?
What is the difference between null pointer and wild pointer?
What are the types of functions in c?
write a program that reads lines(using getline), converts each line to an integer using atoi, and computes the average of all the numbers read. also compute the standard deviation.
