C
Chris Hills
Alan said:
Unfortunately both are wrong... A byte AFAIK is the smallest amount you
can address on a MCU/CPU. Now 95% of the time it is 8 bits but in the
past it has been many other things.
Unfortunately both are wrong... A byte AFAIK is the smallest amount you
can address on a MCU/CPU. Now 95% of the time it is 8 bits but in the
past it has been many other things.
C
Chris Hills
Alan said:
We keep having this argument. SOME users want to limit the scope of this
NG and other want to widen it. As there is no charter the majority will
eventually prevail.
I don't think so. My Father who has been in computing since 1952 would
not agree with you. AS you say....
Actually many other "older computers that is pre the mid-late 1980's
when the PC and other 8 bit "home" computers came to prominence. A byte
width of all sorts of sizes was used previously.
Bytes were *usually* but not always the same size as a single character
the character set being used.
Characters were all sorts of sizes (I have a comms program that would
handle 4 to 9 bits)
I though a char could hold a character. Some systems use less than 8
bits and some more but, in the past these were not always multiples of 8
bits.
Because the size of byte is variable we used OCTET for 8 bits in the
comms industry where PC's are not common.
F
Flash Gordon
Richard said:
Obviously too early on a Sunday morning. I'm so used to seeing >=8 I
misread it.
P
pete
Chris Hills wrote:
In C, which is the topic here of this newsgroup,
the "size" of a type, is measured in bytes.
The "width" of a byte, varries according to the implementation.
CHAR_BIT from limits.h, is the width of a byte.
In C, which is the topic here of this newsgroup,
the "size" of a type, is measured in bytes.
The "width" of a byte, varries according to the implementation.
CHAR_BIT from limits.h, is the width of a byte.
T
Tomás
Chris Hills posted:
Incorrect.
On a particular system, it's okay if:
A) The smallest amount of memory addressable is 16 bits.
B) A char is 8 bits. (And thus a byte is 8 bits).
To facilitate this on this particular system, a char* holds more info than
an int*, because it also specifies whether it wants "the first 8 bits or
the last 8 bits".
-Tomás
Incorrect.
On a particular system, it's okay if:
A) The smallest amount of memory addressable is 16 bits.
B) A char is 8 bits. (And thus a byte is 8 bits).
To facilitate this on this particular system, a char* holds more info than
an int*, because it also specifies whether it wants "the first 8 bits or
the last 8 bits".
-Tomás
O
osmium
:
I'll be damned! In Note 2, they defined byte very precisely as a word that
simply means a collection of contiguous bits. They took a widely used
word, that meant something to hundreds of thousands of people and redefined
it to mean something entirely different.
There are about 30 definitions of byte that make the cut on google, and the
*vast* majority say a byte is eight bits.
http://tinyurl.com/j79j4
That's simply appalling! Now the world needs a committee to define a word
for eight contiguous bits. How about naming it in honor of the clown who
got that inserted into the standard?
Historically, the smallest addressable unit of storage was a character.
They seem to have gotten tangled up and ignored the distinction between a
character and a character code, and ignored the fact hat they were different
things. I think this made up example from history is right: The IBM 7094
has a six-bit character. The character code is BCD.
Note that addressable does not imply that a single character can be read
from memory, it only means there are hardware instructions to do something
useful at this level.
I'll be damned! In Note 2, they defined byte very precisely as a word that
simply means a collection of contiguous bits. They took a widely used
word, that meant something to hundreds of thousands of people and redefined
it to mean something entirely different.
There are about 30 definitions of byte that make the cut on google, and the
*vast* majority say a byte is eight bits.
http://tinyurl.com/j79j4
That's simply appalling! Now the world needs a committee to define a word
for eight contiguous bits. How about naming it in honor of the clown who
got that inserted into the standard?
Historically, the smallest addressable unit of storage was a character.
They seem to have gotten tangled up and ignored the distinction between a
character and a character code, and ignored the fact hat they were different
things. I think this made up example from history is right: The IBM 7094
has a six-bit character. The character code is BCD.
Note that addressable does not imply that a single character can be read
from memory, it only means there are hardware instructions to do something
useful at this level.
R
Richard Heathfield
Tomás said:
Well, the underlying system can be like that, but if so, a conforming
implementation must either set CHAR_BIT as 16 or do some magic to make it
appear as if octets are addressable individually.
Chris is perfectly correct, from a C perspective.
Well, the underlying system can be like that, but if so, a conforming
implementation must either set CHAR_BIT as 16 or do some magic to make it
appear as if octets are addressable individually.
Chris is perfectly correct, from a C perspective.
P
P.J. Plauger
We forgot to do a web search before we chose that terminology in 1983.
P.J. Plauger
Dinkumware, Ltd.
http://www.dinkumware.com
O
osmium
P.J. Plauger said:
I appreciate your sarcasm and have no desire to argue with anyone - and most
certainly not with you.
But wasn't the word byte pretty much introduced into the world by the IBM
360 in 1964 or thereabouts?
R
Richard Heathfield
osmium said:
Knuth says that the 8-bit "standardisation" happened in around 1975 or so.
By then, C was already well under way, and dmr was almost certainly
accustomed to using the word in its non-"standard" sense.
Knuth says that the 8-bit "standardisation" happened in around 1975 or so.
By then, C was already well under way, and dmr was almost certainly
accustomed to using the word in its non-"standard" sense.
M
Martin Ambuhl
osmium said:
No. The word "byte" was common long before 1964, and with many machines
when no one had ever hallucinated a 360. In fact, it is from 1956,
coined by Werner Buchholz.
At least you got the company right. Otherwise, you have wrong
the date: 1956, not 1964
the computer: IBM Stretch, not IBM 360
You probably got the size wrong, too. Its orginal incarnation was 1 to
6 bits, not 8. The Dec family, especially the PDP-6 and -10 nicely
extended this to 1 to 36 bits.
K
Keith Thompson
Tomás said:
Then an 8-bit byte is addressible (with a little extra effort by the
compiler).
K
Keith Thompson
Chris Hills said:
There is currently exactly one newsgroup where we can discuss standard
C without getting bogged down in system-specific or otherwise
irrelevant details. (comp.lang.c.moderated is too slow, and
comp.std.c has a different purpose.) Some users want us to have *no*
such newsgroup at all. It's possible that they'll eventually prevail,
but I sincerely hope they don't.
Chris, I've asked you a couple of questions on this topic, and you've
never answered them.
You mentioned other (non-Usenet) forums where people discuss the C
programming language. I'd like to take a look. Where are they?
If you think the current topicality guidelines should be changed,
*how* do you think they should be changed? Can you give specific
examples of things you think should be considered topical that
currently aren't? If there were a charter for this newsgroup, what
should it say?
K
Keith Thompson
osmium said:
No, the term "byte" did not originally mean exactly 8 bits.
<http://www.catb.org/~esr/jargon/html/B/byte.html> says:
byte: /bi:t/, n.
[techspeak] A unit of memory or data equal to the amount used to
represent one character; on modern architectures this is
invariably 8 bits. Some older architectures used byte for
quantities of 6, 7, or (especially) 9 bits, and the PDP-10
supported bytes that were actually bitfields of 1 to 36 bits!
These usages are now obsolete, killed off by universal adoption of
power-of-2 word sizes.
Historical note: The term was coined by Werner Buchholz in 1956
during the early design phase for the IBM Stretch computer;
originally it was described as 1 to 6 bits (typical I/O equipment
of the period used 6-bit chunks of information). The move to an
8-bit byte happened in late 1956, and this size was later adopted
and promulgated as a standard by the System/360. The word was
coined by mutating the word .bite. so it would not be accidentally
misspelled as bit. See also nybble.
(I would dispute the use of the word "invariably".)
C
Chris Hills
Keith Thompson <kst- said:
I have them marked for reply and feeling guilty I have not done so. It
needs thinking about for specific answers and I have been busy this week
and did not want to just dash off a quick reply.
I found some on both Yahoo and Google. The problem is it is very easy on
Yahoo to start a group compared to usenet. SO some people never get past
the web interface of Yahoo and to the usenet groups.
It came as quite a surprise to me that there were so many c, c++ 8051
and 8 bit MCU Yahoo groups. People how have no idea that there is a
comp.arch.embedded. Eventually the people using some of the usenet the
technical groups are going to fade away and not be replaced.
That is a good idea.... can we draw up a charter? It would mean people
have to think about it. I did not replay to your "specific" question as
it needed some thought and I did not want to do an off the cuff reply.
The problem is it is difficult to be specific on vaguely loosening a
tight spec.
O
osmium
Chris Hills said:
<I *think* that pruning is right>
My guess is that the question is more along the lines of "If I gave you a
million dollars, what would you do with it?".
C
CBFalconer
Chris said:.... snip ...
That is a good idea.... can we draw up a charter? It would mean
people have to think about it. I did not replay to your "specific"
question as it needed some thought and I did not want to do an off
the cuff reply.
The problem is it is difficult to be specific on vaguely loosening
a tight spec.
If you are going to make a proposal then I suggest you start from
"the tight spec". Remember that even now things involving POSIX
are adequately housed on comp.unix.programming (or such) and
windows (cursed be its name) on microsoft.*.
One loosening that might be worthwhile is advice on how to make
various almost-C compilers hew to the various standards, and their
failings.
--
"If you want to post a followup via groups.google.com, don't use
the broken "Reply" link at the bottom of the article. Click on
"show options" at the top of the article, then click on the
"Reply" at the bottom of the article headers." - Keith Thompson
More details at: <http://cfaj.freeshell.org/google/>
Also see <http://www.safalra.com/special/googlegroupsreply/>
C
Chris Hills
osmium said:
500K on wine, women and parties. Then just fritter the rest away
P
P.J. Plauger
As others have pointed out in detail, byte is an old word. IBM's System/360,
introduced in the early 1960s, began the modern trend to eight-bit bytes
and byte-resolution arithmetic. Nevertheless, in the 1980s it was still not
uncommon to refer to "an x-bit byte machine", where x assumed quite a few
different values. Thus, the C Standard hardly plowed any new ground in
this area, and certainly didn't defy common parlance of the time.
P.J. Plauger
Dinkumware, Ltd.
http://www.dinkumware.com
M
Mike S
Richard said:No, that almost certainly means simply that you've got a Windows text file
on a Linux system. Linux doesn't know, bless it, that you've been sullying
its filesystem with foreign muck.
Sorry, I should have explained myself more clearly. At the moment I am
running on Windows with a Windows port of gcc. But, before I get
off-topic with environment specs, my real question is simply: does the
Standard require that stdin, stdout, and stdout be opened in a known
mode or is this detail left to the compiler? I ask because if I compile
the following (say as test.exe):
#include <stdio.h>
/* count occurences of '\r' in the input stream */
int main()
{
int c, count;
count = 0;
while ((c = getchar()) != EOF)
if(c == '\r')
++count;
printf("counted %d \\r's in input.\n", count);
return 0;
}
and I run the program with itself as input ("test < test.c"), the
result (on my machine) is
counted 12 \r's in input.
However, as I understand it, any '\r\n' sequences in the input stream
should have been mapped to '\n'. The only literature I can find
relating to this is what Microsoft has to say about how their C
compilers open stdin (they say it is opened in text mode in their
compilers). But what does the ANSI/ISO Standard say about what mode
stdin, stdout, and stderr are opened in? Maybe my compiler is just
misbehaving...
Mike S