# Thread: Releavance of bit fields to a tester

1. ## Releavance of bit fields to a tester

What relevance would a 9-bit field have to a tester?

I asked a question about the range of values that could be entered into a field and was told that it was a 9-bit field. However, the developer could not tell me how this pertained to me wanting to know if I could enter values from 0 to 550.

Has anyone else met with such a instance and knew how to interpret how the different bit fields coincide with value ranges?

Anie

2. ## Re: Releavance of bit fields to a tester

No, I have not encountered a developer who wouldn't understand the relationship between bits in a field, and range of values.

Clearly a 9-bit field (unusual?) could store 0 - 511 if unsigned.

511 dec = 111111111 bin

(You can use the Windows calculator in Scientific view to assist with this if you like)

[img]images/icons/shocked.gif[/img]

3. ## Re: Releavance of bit fields to a tester

http://www.inf.ufsc.br/~bratti/assem...ntationa7.html
Explains the concept of bit fields and packed data real well. So I am a happy camper!!!

4. ## Re: Releavance of bit fields to a tester

thanks for ur informstion about bits anie

5. ## Re: Releavance of bit fields to a tester

It's ashame I didn't see your answer earlier, Joe because that helped me all the more to understand it.
Especially the binary information. I was puzzled about that, but thanks to you no longer.
You also cleared up some things that the website didn't explain.
However, you mention unusual? I'm new to this so can you tell me why a 9-bit field is unusual. I'm looking at a military specification catalog regarding the bit information. I'm even seeing some fields that go up to 420-bits. All of the fields seem to be measured into bits.

***********************************************
Anie

6. ## Re: Releavance of bit fields to a tester

Joe have you ever heard of Octal????
That makes the max number 999

7. ## Re: Releavance of bit fields to a tester

999 in octal ???
Is this something like hhh in hex? [img]images/icons/wink.gif[/img]

8. ## Re: Releavance of bit fields to a tester

I'm new to this so can you tell me why a 9-bit field is unusual.
<font size="2" face="Verdana, Arial, Helvetica">I'll jump in here to give Joe's fingers a rest [img]images/icons/smile.gif[/img]

It's unusual because its -- well -- unusual! Of course in theory a field can be any number of bits in length, but there is usually some particular reason for the length (4 bits for BCD. 7 or 8 bits for other character representations. 16, 32 or 64 bits for typical word lengths - some fellow old farts may also recall 24 and 48 bit words. 128 bit encryption keys. And so on and so on.) But 9 bits is just not a commonly-encountered length. (Although as Rich obscurely implied, it can represent 3 octal digits, or 777 - not 999).

9. ## Re: Releavance of bit fields to a tester

Originally posted by Rich W.:
Joe have you ever heard of Octal????
That makes the max number 999
<font size="2" face="Verdana, Arial, Helvetica">999 in octal?

That does not compute...

10. ## Re: Releavance of bit fields to a tester

Originally posted by Anie:
However, you mention unusual? I'm new to this so can you tell me why a 9-bit field is unusual.
<font size="2" face="Verdana, Arial, Helvetica">It's just something I don't see much of these days.

I remember the days when disk storage was very, very expensive, and I had to write routines to pack data into as few bits as possible.
There, we had all sorts of bit lengths for fields.

Wow, that made me sound old... "My story begins in nineteen-dickity-two. We had to say "dickity" cause the Kaiser had stolen our word for "twenty". I chased that rascal to get it back, but gave up after dickity-six miles..."

Anyway, with inexpensive disk storage, and standard databases with standard field sizes, I just don't see that very much now.

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