Parity Bit (1 Viewer)

[tooheyz]

hey everyone...

i just got an exam back today and im confused. the question was weather or not asynchronus transmission has a parity bit or not. i answered YES as with all my friends, but the d*ckhead of the teacher said NO, no matter how much we screamed at him. i checked in the text book and it doesnt say anything..

so r we right.. or did we rock ourselves?

 

[Lazarus]

I found the following excerpt:

Asynchronous communication requires additional bits to be added around actual data in order to maintain signal integrity. Asynchronously transmitted data is preceded with a start bit which indicates to the receiver that a word (a chunk of data broken up into individual bits) is about to begin. To avoid confusion with other bits, the start bit is twice the size of any other bit in the transmission. The end of a word is followed by a stop bit, which tells the receiver that the word has come to an end, that it should begin looking for the next start bit, and that any bits it receives before getting the start bit should be ignored. To ensure data integrity, a parity bit is often added between the last bit of data and the stop bit. The parity bit makes sure that the data received is composed of the same number of bits in the same order in which they were sent. See Figure 8 for a portrayal of how asynchronous communication works.

http://www.quatech.com/Application_Objects/FAQs/comm-over-asyncserial.htm

Appears as though it doesn't have to be used, but conventionally it is. The exact wording of the question would be nice.

 

[tooheyz]

yeah the teacher said that it doesnt really need it...

here is the question... its in the HI textbook... i found it in there yesterday..

question

gloria connected to a remote comp. she used the follwing communication settings: 7 bit ascii, 1 start and stop bit, odd parity and 4800 baud. what is the type of transmission? explain the type of error detection methis used and one major deficiency of this method? and describe an alternative error detection methid that would provide better results...

it was a 5 mark question... and i got 4 marks... i lost a mark for saying that it was ASYNCHRONOUS transmission... but the stupid teacher thinks otherwise

 

[hurrotisrobbo]

Hey, at least your teacher acknowledges that the parity bit is the 8TH bit, not an extra 9TH bit (A 9-bit byte? Hmm...).

*Grumph*

 

[tooheyz]

hmm.. seems to me that all ipt teachers r dumb...

 

[Lazarus]

Originally posted by ToOhEyZ
she used the follwing communication settings: 7 bit ascii, 1 start and stop bit, odd parity and 4800 baud.

i lost a mark for saying that it was ASYNCHRONOUS transmission

Well, one wonders why she would be using start and stop bits if it was synchronous transmission?

I could've sworn they were only used in asynchronous transmission (because the whole point of synchronous transmission is that the two computers are synchronised). Then again it's been two years since I've done this.

 

[Supaneo]

Originally posted by ToOhEyZ
hmm.. seems to me that all ipt teachers r dumb...

That's hiliarous, THU

I once had a weird intention on becoming an IPT teacher for some reason...

Would that make me dumb as well? hmmm

I guess so...

If i were an IPT teacher i reckon i would be so bad depending on what school i taught at and what facilities it had to provide...

I thought my school but i couldnt help the students mocking me due to the fact that i went to the school how many years from when i left....

oh well
how you doing btw?
havent seen you in ages...
when was it last... wit ET

 

[Huy]

Originally posted by ToOhEyZ
hmm.. seems to me that all ipt teachers r dumb...

i'll agree with you there,
mine is nothing without a textbook



further, we haven't used a computer in months...
a sad state of affairs,

hi vinh

anyway, it wouldnt be synchronous as lazarus has stated, since it's more efficient than async. (no extra bits)

i guess you'd get some marks for saying serial trans, parity checks, crcs, checksums and all the rest of it.

using parity checking you'd have chars represented as 8-bit ascii's with the ninth bit being used as the parity (0/1).

 

[tooheyz]

Originally posted by Huy


i'll agree with you there,
mine is nothing without a textbook

yeah my teacher follows the text book and not the syllabus. how *fudged* is that?!

 

[jessika]

Originally posted by ToOhEyZ


yeah my teacher follows the text book and not the syllabus. how *fudged* is that?!

um hello! your teacher actually does SOMETHING that related to the course.