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Number System

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Anonymous
a b G Storage
January 12, 2005 9:46:03 AM

Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

I read about Number system but there are some points where my concepts
are not clear .I will be very great full to you if you rely following
questions to clarify my concepts:

1-What is the application of ASCII and EBCDIC (where these two code
systems are used)?

2-Which coding scheme (number system) is used by computer [of course it
is binary but what type of binary ASCII or EBCDIC]?

3-Since ASCII and EBCDIC are 8 bit coding schemes what about a number
255 or greater than 255 how can we store/write these numbers in ASCII
and EBCDIC?

4-What is the application of base-8, base-16 in computer [how these
number systems are used by computer as binary (as base-2 numbers are
used by digital circuits)]?

5-In simple binary 1111=15 of decimal but 1111 of binary=11110001
11110101 in
EBCDIC and 00110001 00110101 in ASCII why three different
representation of 15 of decimal in simple binary ,ASCII and EBCDIC?

6-Why in addition of two positive numbers we preserve all bits but in
addition of one positive and one negative number we discard bit/s if
exceed by the max no of bits as compare to the largest digit.
For e.g.(1) 101+110=1011 [in binary] we preserve all four bits even in
the question the largest number consist of three bits or 5+6=11[in
decimal]

e.g. (2) But 110+011=001( actual answer is 1001 but we discard right
most bit) [in binary] [since the 2 complement of +5(101) is -5(011)]or
6+(-5)=1{in decimal}]
Why in e.g.(1) we preserve all bits but in e.g. (2) we discard right
most bit ?

7- if we just have number [not mention that its +ve or -ve ] 101 in
base-2 how we treat this a positive number or negative number?
Regards

More about : number system

Anonymous
a b G Storage
January 12, 2005 5:03:02 PM

Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

I smell homework, and misdirected homework at that--this doesn't really have
a lot to do with storage.

Further, this should be covered adequately in your text, handouts, and
lecture notes. Have you even _tried_ those resources? Have you _tried_
googling some of the keywords?

rehhman wrote:

> I read about Number system but there are some points where my concepts
> are not clear .I will be very great full to you if you rely following
> questions to clarify my concepts:
>
> 1-What is the application of ASCII and EBCDIC (where these two code
> systems are used)?

In electronic communication of course.
>
> 2-Which coding scheme (number system) is used by computer [of course it
> is binary but what type of binary ASCII or EBCDIC]?

Yes.

> 3-Since ASCII and EBCDIC are 8 bit coding schemes what about a number
> 255 or greater than 255 how can we store/write these numbers in ASCII
> and EBCDIC?

What about it? How do you write "3" in ASCII and EBCDIC? And when did
ASCII become an 8-bit scheme? Isn't that "extended ASCII"?

> 4-What is the application of base-8, base-16 in computer [how these
> number systems are used by computer as binary (as base-2 numbers are
> used by digital circuits)]?

Ancient history.

> 5-In simple binary 1111=15 of decimal but 1111 of binary=11110001
> 11110101 in
> EBCDIC and 00110001 00110101 in ASCII why three different
> representation of 15 of decimal in simple binary ,ASCII and EBCDIC?

Because if they were all the same then binary, ASCII, and EBCDIC would be
the same?

> 6-Why in addition of two positive numbers we preserve all bits but in
> addition of one positive and one negative number we discard bit/s if
> exceed by the max no of bits as compare to the largest digit.
> For e.g.(1) 101+110=1011 [in binary] we preserve all four bits even in
> the question the largest number consist of three bits or 5+6=11[in
> decimal]

Huh?

> e.g. (2) But 110+011=001( actual answer is 1001 but we discard right
> most bit) [in binary] [since the 2 complement of +5(101) is -5(011)]or
> 6+(-5)=1{in decimal}]
> Why in e.g.(1) we preserve all bits but in e.g. (2) we discard right
> most bit ?

Find out what "2s Complement" really means.

> 7- if we just have number [not mention that its +ve or -ve ] 101 in
> base-2 how we treat this a positive number or negative number?
> Regards

1.


--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
Anonymous
a b G Storage
January 14, 2005 6:24:49 PM

Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

En 1105541163.441503.282520@c13g2000cwb.googlegroups.com, rehhman va
escriure:
> 2-Which coding scheme (number system) is used by computer [of
> course it is binary but what type of binary ASCII or EBCDIC]?

Neither. Computer do not speak English, they do not need to encode 'a', so
they do not need to decide if it is better to use 97 or 129.


> 3-Since ASCII and EBCDIC are 8 bit coding schemes

Since ASCII is AFAIK a 7-bit scheme, I do not understand the question.


> 4-What is the application of base-8, base-16 in computer [how these
> number systems are used by computer as binary (as base-2 numbers are
> used by digital circuits)]?

Base 8: never seen (well not completely true, my first computer allowed
operating on base 8, although with only one digit; but it was so
rudimentary; it did not know how to sum...)
Base 16: only seen for floating point unit and BCD. Which are one level
higher than digital circuits.


> 5-In simple binary 1111=15 of decimal but 1111 of binary=11110001
> 11110101 in
> EBCDIC and 00110001 00110101 in ASCII why three different
> representation of 15 of decimal in simple binary ,ASCII and EBCDIC?

Because. You can also find 00010101, 1111111, MMMMMMSS, and a number of
other cases.

> 6-Why in addition of two positive numbers we preserve all bits

Huh? Do you remember that thing called "borrow" when you were taught how to
add, on your first term? It still exist in 21st century, you know!
Your example just show how we need one more bit...


> 7- if we just have number [not mention that its +ve or -ve ] 101 in
> base-2 how we treat this a positive number or negative number?

Base has nothing to do here. The sign is just something you need to add
somewhere, so you need to encode it if you need it. In writing, a signless
number is just a string of digits, a negative one is one minus followed by a
string and a positive is one plus followed by a string. Whether there are 2
or 60 different possible digits is irrelevant.


Antoine
Related resources
Anonymous
a b G Storage
January 15, 2005 10:51:29 PM

Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

Hi,

Its not home work yes I tried all available books and net but have not
find the answer of those question that I asked u any how, thanx a lot
for replying me .

You asked that What about it? How do you write "3" in ASCII and EBCDIC?

Since both extended ASCII and EBCDIC are 8 bits that must have 00000011
the equivalent of 3.Since the equivalent of 255 is 100000000 and this
number is consist of 9 bits that mean we cant store number greater
than225 in extended ASCII and EBCDIC as they are 8 bits coding
scheme[thatz the confusion I have]

Regards
Anonymous
a b G Storage
January 15, 2005 10:52:46 PM

Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

Hi,

In Q 3 I a wanna ask

Since both extended ASCII and EBCDIC are 8 bits that must have 00000011
the equivalent of 3
Since the equivalent of 255 is 100000000 and this number is consist of
9 bits that mean we cant store number greater than225 in extended
ASCII and EBCDIC as they are 8 bits coding scheme[thatz the confusion I
have]


Regrads
Anonymous
a b G Storage
January 16, 2005 6:34:04 AM

Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

rehhman wrote:

> Hi,
>
> In Q 3 I a wanna ask
>
> Since both extended ASCII and EBCDIC are 8 bits that must have 00000011
> the equivalent of 3
> Since the equivalent of 255 is 100000000 and this number is consist of
> 9 bits that mean we cant store number greater than225 in extended
> ASCII and EBCDIC as they are 8 bits coding scheme[thatz the confusion I
> have]

Did you google "ascii ebcdic"? When I tried it I found quite a lot of
information.

> Regrads

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
!