# Megabit?
**URL:** https://boards.straightdope.com/t/megabit/36517
**Category:** Factual Questions
**Created:** [October 11, 2000, 6:40am UTC](https://boards.straightdope.com/t/megabit/36517 "2000-10-11T06:40:00Z")
**Posts on this page:** 5
**Page:** 4
### Author:  [@douglips](https://boards.straightdope.com/u/douglips)
#### Post date: [October 13, 2000, 10:29pm UTC](https://boards.straightdope.com/t/megabit/36517/61 "2000-10-13T22:29:03Z")
Yes, a byte has 8-bits in current usage almost universally. But sailor quoth:
> [@](#):
>
> I think it is safe to say that the definitions of words would derive from their common usage. That is the way dictionaries are made, they find instances of the word and interpret the meaning. When a meaning is common, then it is included in the definition. A single or very few instances would not be enough and you cannot supply a single one.
>
> I have searched the net and cannot find a single one! I think I am safe in saying the only common use of byte today is to mean 8 bits. You disagree but you cannot find _any_ support for your assertion. Well, what can I say? Ok, whatever.
Points:
[ul][li]“I have searched the net and cannot find a single one” ne “you cannot supply a single [instance]”. You obviously didn’t look very hard.[/li][li]I agree with you that insisting that bytes do not necessarily have 8-bits borders on the pedantic.[/li][li]I agree with you that a few instances would not be enough to establish a common use.[/li][li]I guess I just had to prove it could be done.[/ul][/li]That being said, here are some usages of 9-bit bytes, found by the shocking innovation of searching for ‘9-bit byte’ on yahoo (google):
[ul][li][http://www.fte.com/techsupp/win32/9bitdata.htm[/li]](http://www.fte.com/techsupp/win32/9bitdata.htm%5B/li%5D)
> [@](#):
>
> Frontline Test System
> How to View the 9th Bit of a Byte
>
> Revision Date: February 10, 2000
Here we are talking about software that reads data from a serial port, and it may need to read 9 bits of data (not 8 bits and a parity) and how you can configure the software to handle that. **Arcane, but recent.**
[li][http://www.ucalgary.ca/it/itf/oldun/AIX/AIX-16.html[/li]These](http://www.ucalgary.ca/it/itf/oldun/AIX/AIX-16.html%5B/li%5DThese) guys (UCalgary) were using Multics (9-bit OS) until 1993, and still have backup tapes. Here is a page from their AIX manual about how to restore 9-bit byte Multics data.
> [@](#):
>
> In particular, the nine-bit byte size and
> security design of Multics are incompatible with AIX. Multics was decommissioned in May 1993, the backup tapes are retained by UCS until they
> are no longer useable (approximately ten years).
Definitely obsolete, but only by 5 years and nowhere near the ‘1956’ date quoted earlier.
[li][http://www.ai.mit.edu/projects/transit/tn15/tn15.html[/li]](http://www.ai.mit.edu/projects/transit/tn15/tn15.html%5B/li%5D)
> [@](#):
>
> Original Issue: May 1990
> …
> To test RN1, we will latch 9-bit data bytes to the ports of RN1 that we wish to drive.
**Arcane and 10 years old.**
[li][http://info.aoc.nrao.edu/vlba/html/TAPES/PLOTS/plottypes.html[/li]From](http://info.aoc.nrao.edu/vlba/html/TAPES/PLOTS/plottypes.html%5B/li%5DFrom) the guys at the VLBA - you know, that big ass radio telescope array from _Contact_.
> [@](#):
>
> All three formats (VLBA, Mark III, and Mark IV) use 9 bit bytes where the 9th bit of each byte is a parity bit.
> …Revised November 13, 1998
They are talking about using one of the 9 bits as parity, but they still call it a 9 bit byte.
[li][RFC 1037](http://sunsite.iisc.ernet.in/collection/rfc/rfc1037.html)[/li]This document dates from 1987 but refers to many byte sizes:
```auto
Byte Size Packing Scheme
7, 8, or 9 bits four per 36-bit word
10, 11, or 12 bits three per 36-bit word
13, 14, 15, or 16 bits two per 36-bit word
```
[/ul]
[/quote]
Also, sailor wrote:
> [@](#):
>
> Nope, the ascii standard was 7 bits and, in fact the internet was all 7 bits and many parts of it remain 7 bits and 8 bit data needs to be encoded. Anyone remember UUENCODE? Ah, memories.
I used to have an ascii text file that was a valid DOS COM file as well. You can see it (or something similar) [here](http://w4dfu.ufl.edu/listarchives/1996/january/msg00014.html). The version I’ve linked to I can’t get to work on NT - maybe because it’s corrupt on the web page, maybe because NT is incompatible with it. Oh well.
It was cool, because it was 7-bit friendly and could be emailed to someone so that they could then be sent a binary uuencoded file and happily decode it. Saved me years of time when I was working tech support in the early 90’s. No more excuses why people couldn’t be emailed a small zip file.
I remember all the dazed sounding people on the other end of the line marvelling that you could just name this text file ‘[uudecode.com](http://uudecode.com)’ and it would work. I used to think I would not be surprised if some of them then thought they could just tack “.exe” onto the end of their source code and have it run.
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### Author:  [@sailor](https://boards.straightdope.com/u/sailor)
#### Post date: [October 13, 2000, 10:54pm UTC](https://boards.straightdope.com/t/megabit/36517/62 "2000-10-13T22:54:54Z")
\>\> You obviously didn’t look very hard
hehe, obviously. I look harder for pages that support my point of view.
That file is interesting. I guess it was designed so none of the bytes had the highest bit set. Quite a feat.
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### Author:  [@douglips](https://boards.straightdope.com/u/douglips)
#### Post date: [October 13, 2000, 11:05pm UTC](https://boards.straightdope.com/t/megabit/36517/63 "2000-10-13T23:05:09Z")
> [@](#):
>
> \*Originally posted by sailor \*
> \*\* \>\> You obviously didn’t look very hard
>
> hehe, obviously. I look harder for pages that support my point of view.\*\*
🙂
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [October 14, 2000, 12:39am UTC](https://boards.straightdope.com/t/megabit/36517/64 "2000-10-14T00:39:50Z")
> [@](#):
>
> I used to have an ascii text file that was a valid DOS COM file as well.
Slight hijack here, but I once saw a file that was a valid “Hello World” in DOS .com object code, Bourne shell script, C, and I think Fortran. The trick is to make each language think that the stuff for the other languages is commented out.
We now return you to your regularly scheduled thread, already in progress.
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### Author:  [@sailor](https://boards.straightdope.com/u/sailor)
#### Post date: [October 14, 2000, 1:41am UTC](https://boards.straightdope.com/t/megabit/36517/65 "2000-10-14T01:41:09Z")
\>\> already in progress
You call this progress? 😉
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