How many bits in a byte?

[Dragonfli]

[Warren DeMontague]

1. 8

[Dragonfli]

2. Very Good, You are not home schooled like some around here!

Now, how many bytes in a kilobyte?
I got to warn you, there is a lot of "faith based conversions" going on here these days, if you answer wrong, it's back to the rats placed over your face for you!

edited because i spell like some people count

[Sgent]

3. 1024

Now, how many bytes in a word?

When do you have 9bit bytes?

[lvx35]

6. as many bytes as letters.

[Sgent]

10. I meant

a binary word -- the answer is variable but currently 1, 2, 4, or 8 depending on ascii, Unicode, etc.

Word can also be used to describe an operational set (the amount used by a CPU) -- so in Intel Pentium 4 it would be 4 byte words.

[Mairead]

23. Variable because originally all it meant was the smallest

uniquely addressable amount of memory. Then they broke through the barrier to byte-addressability and 'word' shifted meaning. I think these days it's a synonym for the width of the data bus.

[The_Casual_Observer]

8. What kind of word?

Single 2
Double 4

[Warren DeMontague]

5. I want to say 1024 but I'll pass on the rats

Really. Oceania has always been at war with Eastasia. I swear.

[Dragonfli]

11. ha ha I agree!

the REAL limit for sig lines is not 19.53125 kilobyte
but 20k just like Brother man says!

http://www.google.com/search?ie=UTF-8&oe=UTF-8&sourceid=deskbar&q=20%2C000+bytes+to+kilobyte+conversion

this link will fall down the memory hole, just as it should in the "brave new DU" along with a 19.7 kilobye sig line that will die with it.

Who needs truth when we have a ministry for such things?

I for one embrace the new faith based math!

[bananas]

20. it can be 1000 or 1024

For memory chips, 1024 is the standard.
For line speed, such as ethernet, dsl, and even dial-up modems,
the standard is 1000.
For disk drives, both are used.
So a 256k DSL line is 256,000 bits/second,
and 100M ethernet is 100,000,000 bits/second.
There is also mixed usage, for example a computer program which process 1024 bytes every millisecond could be said to process a megabyte a second, using mega as 1024*1000 instead of 1024*1024 or 1000*1000.

Note those are "standard usage".
According to the offical SI standard, kilo is always 1000, never 1024,
the prefix kibi is 1024.

This wiki article seems to explain all this.
http://en.wikipedia.org/wiki/Binary_prefix

[lvx35]

4. and a baud is a bit, not a byte.

Therefore a 56k (kilobaud) modem only downloads 7k (kilobytes) a second, max...When you 'd think it could download 56k.

[The_Casual_Observer]

9. Bits/sec

[uberotto]

12. Wrong! It is 56 Kbit Modem. Baud is sample frequency...

From Computer Networks, vol 4 by Andrew Tannenbaum:

"The telephone channel is about 4000 Hz wide... The maximum number of independent samples per second (baud rate) is 8000 (determined by Nyquist theorem). The number of bits per sample in the U.S. is 8, one of which is used for control purposes, allowing 56,000 bits/sec of user data...

The modem standard is called V.90. It provides for 33.6 kbps upstream channel, but a 56 kbps downstream channel..."

The reason 56 kbits/sec (or 7 kbytes/sec) modems rarely transfer data at that rate has to do with the quality of the telephone system. Most telephone lines are too noisy to work at this level so you usually see a transfer rate around 4 to 5 kbytes/sec. Do a search for Shannon theorom for more information.

Some Additional Information:
V.32 protocol: 2400 baud, 4 bits per sample = 9600 bits/sec modem
V.32 bis protocol: 2400 baud, 6 bits per sample = 14,400 bits/sec modem
V.34 protocol: 2400 baud, 12 bits per sample = 28,800 bits/sec modem
V.32 bis protocol: 2400 baud, 14 bits per sample = 33,600 bits/sec modem

For additional information do a search for Quadrature Phase Shift Keying (QPSK).

[lvx35]

17. Oh yeah?

well you...you...um...HATE AMERICA! humph!

[TahitiNut]

13. While "close enough for government work," that's not really accurate

'Baud' (named after Emile Baudot) is a measure of signalling rate or the number of transitions per second in a modulated signal. While in some primitive systems, the data rate (typically measured in bits/second) is the same as the signalling rate, it's possible (and usual, now) to encode multiple bits in one transition event. The old (but not "oldest) 2400 bit/sec modems operated at 600 baud, using "quadrature amplitude modulation" (or QAM). QAM, still in use, encodes 4 data bits per transition event.

Anyone "in the biz" (telecommunications/teleprocessing) will spot an amateur (poser) immediately if they make the "baud=bit" assumption.

(Oh ... and 56kb modems don't actually achieve 56kb in actual use.)

On edit: Also, be aware that the data rate of the transmission device/interface DOES NOT equate to the amount of program/computer data one sees on the computer (in a file, for example). Each 8-bit byte is typically trasmitted with two additional bits (a parity bit and a stop bit) for the purposes of transmission quality. Thus, the data 'yield' is often only 80% of the actual data rate (which is usually 33.3 kb/s downstream under optimum conditions on a 56kb/s modem.) It gets even more complicated when protocol-based data compression is used in the transmission channel.

[Dragonfli]

15. With the new "faith based math"...

Anything is possible! Don't you see? Why, I could say now to someone, "I can sell you, a gallon of gas, real cheap", and then just give them 10 ounces and simply "call it" one gallon. Your rules of math are part of the "reality based community", get with the program will ya :eyes: We create our own math reality here!

on edit-I wish I believed in faith based speelling!

[lvx35]

16. Damn Liberals.

Baud == Bit is 7th commandment of my new faith based computer science display, which I expect to be displayed in every government building that uses computers in a large stone monument. Can you believe the nerve of these liberals? Don't they know that the founding fathers agreed with me that a baud should equal a bit? What's wrong with them!

[Warren DeMontague]

7. Whoa. I am so not getting involved in whatever fight you folks are having

I'll stick to the safe subjects, like porn, videogames, libertarianism and Israel.

[craigolemiss]

14. there is really no answer

the 1024 is actually a K or kilobyte--or number of words to be stored in a section of memory--a realistic number for bits in a byte is the usually accepted 8 but when the verbage was first introduced, all a byte was was to be the size of the word sent to the processor at one time.

In 74-75 I utilized a processor made by Rockwell that has a 13 bit byte. 12 of the locations were for information and the 13th was a check digit. This was actually a processor system made for core memory and was in today's standards somewhere just past the stone age. it was also the processor system that landed on Mars with the original Viking 1 and 2 missions.

[wli]

18. computer programmer's answer here

All modern computers have 8 bits in a byte. This is not a hard rule. Older computers showed much more variety in their design and differed here. Some machines were bit-addressed, others were word-addressed (I don't recall any specific examples). 36-bit computers (esp. DEC) had a "fungible" notion of byte, where they could be considered to have 9-bit bytes but more typically used 7-bit characters packed into 36-bit words. I'm not aware of other significant deviations apart from those I've just mentioned.

[Solo_in_MD]

21. Ahhh, someone with a knowledge of computer history

Word: The smallest amount of memory the processor can reference in a single cycle. Normally 8,16,32, or 64 bits theses days. Those figures do not include parity or ECC.

Byte: Partial word. Notionally 8 bits. Again, this number do not include parity or ECC. Pragmatic use is 1 byte = 1 character in ASCII = 8 bits.

Historically there were computers that used 36 bit words and 48 bit words. For the 36 bit word machine, a byte was 6 bits.

There is also an alternative character representation call EBCDIC which support characters and control sequences not found in ASCII. Based on punch cards (hollerith codes). Good page on the differences is here http://www.dynamoo.com/technical/ascii-ebcdic.htm though I do not agree with the author in some areas.

[Mairead]

24. CDC Cyber machines used a 6-bit 'half-ascii' byte packed 10 to a word

I mean the older Cybers of course, before the air-cooled 800 series.

[wli]

25. very interesting, I wasn't aware of the CDC Cyber char. encoding

That very likely made case-sensitive text awkward if it was ever used (it's more likely an indication that it was case-insensitive).

[Mairead]

26. You're right, it started as caps-only, but then when that became

unacceptable the cyber architecture was still far too good to be discarded, so they kludged a teletype-like solution: a toggle-case char. Or perhaps it was 2 chars, up and down, I can't remember. I think it (or one of them) was octal 76.

Perhaps I should have mentioned, too, that the i/o coprocessors, the PPUs, had a 12-bit word. Weird machine, but, like all of Seymour's, stunningly fast.

[skids]

19. 00001000. n/t

[CabalPowered]

22. I used to ask this question on our job application

:)