Please create an account to participate in the Slashdot moderation system


Forgot your password?

Comment Re:"they" can fuck off, the binary units are the o (Score 1) 618

You know that a bit is an object that can be counted (like every other object in the world) in any base at all, right? You know that a bit represents the number 1 and nothing more, right?

And while we're on your stupid assertion that things that can represented must be counted in binary, please explain why everybody in the world refers to 64KB, 3Gb, etc. Nothing like mixing two different bases in the same number to really confuse things (or maybe you think 64 and 3 are binary numbers). And why are file sizes displayed in base 10? Or does simply abusing the well-known prefixes 'kilo', 'mega', etc mean that we magically switch to some base 2 system of counting (but only for what the prefix represents, not the number itself)?

Comment Re:"they" can fuck off, the binary units are the o (Score 1) 618

I assume you would like to look less like an idiot in the future, so I will provide information with references for your education.

"There is no such thing as a half bit"

In communications, a half bit is a signal that is on the wire for half of the time of a full bit. Here is a datasheet from a UART manufacturer. On page 4 they describe the 'line control register' which sets how many stop bits there are: 1, 1.5, or 2. A simple search will return many references to start/stop bits in async communications.

"Ethernet does not have packets"
The IEEE, Cisco, Wikipedia, and Wireshark would all disagree with that, as would anyone who knows anything at all about networking.

Your little quote you posted provides no support for your position at all. Nobody ever said maximum numbers (such as data lengths) were not going to be in powers of two, or that calculations such as CRC would not be in powers of two. What I said was that data is not naturally (or even usually) transmitted in power of two increments, and you have shown absolutely nothing to disprove that.

Comment Re:"they" can fuck off, the binary units are the o (Score 1) 618

'Early networking involved powers of two'. Really? 'Early networking' would be dialup, right? So what were the common speeds - 110, 300, 1200, 2400, 4800, 9600, 14400, 28800, 33600, 56600. Yep, powers of two all. Ethernet - nope, no powers of two there either. How about token ring? Nope, no powers of two there.

The only thing you said that is correct is that it makes sense for virtual pages to be powers of two. However, virtual pages have nothing to do with disk, other than disk is used for paging space. And of course the first systems to have virtual memory (back when it was really critical that things be as efficient as possible) didn't use disks with 512 byte sectors.

Comment Re:"they" can fuck off, the binary units are the o (Score 1) 618

You have posted more stupidly incorrect information in this forum than I have ever seen before.

Packet sizes are even powers of 2? Since when? Going back to async days, a 'packet' consisted of 1, 1.5, or two start bits, 5-8 data bits, 0 or 1 parity bit, and 1 or two stop bits. So the 'smallest packet would be 7 bits, and the 'largest' packet would be 13 bits. Where are your even powers of 2?

Oh, you didn't mean async, you meant something more modern, like Ethernet, right? OK, so what is the most common ethernet packet size? 1500 bytes. Yup, nice even power of two. Oh, maybe you meant token ring. Hmm token ring packets must be anywhere between 4 and 4051 bytes long. Yup, nice even powers of two.

Comment Re:"they" can fuck off, the binary units are the o (Score 1) 618

I don't think I have ever read so much incorrect information in one place before. Congratulations! By the way, I have over thirty years experience doing hardware design and assembly programming.

First, to your addressing question. I don't know if you are talking about segment-register type addressing, or bank-select type addressing, but in either case you are completely wrong. In degment register addressing, the processor performs the calculation of merging your 16-bit 'address' with the current segment, and drives the addressing lines accordingly. In bank-select addressing you pre-select a 'bank' of memory, and the addressing lines from the processor select the appropriate location within the bank. In either case, if you can address 4G then you have 32 addressing lines, either all directly from the processor, or perhaps with some coming from an external bank-select register.

I already said it does not matter what the unit is being selected (bit, byte, word, line, whatever). The addressing does not change based on the size of the data, on the number of data lines changes.

WTF does something being measured in bits-per-second have to do with powers of two? Not a damn thing. Bits can REPRESENT powers of two, but they do not OCCUR in powers of two. If you can't understand that distinction you are really even more clueless than I thought. In memory components, bits/bytes/whatever OCCUR in powers of two. You can't buy a 1000 (not a power of two) byte memory chip, you can buy a 1024 byte (a power of two) chip. You can't buy a 3072 byte (not a power of two) chip (well maybe there is some weird chip like that but it would be special purpose), the next highest size is 4096 (a power of two). However, you certainly CAN send exactly 1000 or 3072, or any other number of bytes across a network. There is absolutely no power-of-two boundary involved there.

Likewise, the size of a harddisk is dependant only on the bit density of the medium. A disk can be manufactured in absolutely any size at all, there is NO 'natural' power of two boundary to disk sizes.

Lastly, grouping bits into 'bytes' or 'words' has nothing to do with powers of two, it has to do with MULTIPLES of bits. There is no reason that the 'word size' of a machine has to be a power of two. IBM mainframes use 24 (not a power of two) and 31 (not a power of two) bit addresses. There have been 6, 10, 12, and 18 bit 'words' in the past. None of those are powers of two. The only thing grouping into bytes does is say that you will always transfer or store a multiple of 8 bits, which has nothing at all to do with powers of two.

Comment Re:"they" can fuck off, the binary units are the o (Score 1) 618

OK, I re-read your post, and it still doesn't make sense. A byte is certainly not '2 to the power of 8' bits, it is 8 bits. The biggest VALUE that can be represented in a byte is 2^8 -1, but who cares about that? Surely you are not suggesting that we measure memory size, network speeed, disk size, etc by the biggest VALUE that can be represented, are you? Because if you are, then a 100Gbps network should, according to you, have a 'speed' of 2^1000000000ps. That makes absolutely no sense at all.

Comment Re:"they" can fuck off, the binary units are the o (Score 1) 618

There is nothing magical about 512 or 4096 byte sector sizes. Those are strictly a convention used by certain operating systems. The same disks that have 512 byte sectors when used on Linux can have 520 byte sectors when used on OS/400. Mainframe ECKD disks don't have sectors at all, they have tracks and records, and a record can be any size at all.

And even if the 512 byte sectors meant something important, all that would mean is that disk sizes would be multiples of 512, not powers of two. So a '1 meg' disk would actually be 1000488 bytes, which is far closer than the 1048576 bytes you get when saying 'meg' is defined as a power of two. A '1 terabyte' disk would be exactly 1000000000000 terabytes vs the 1099511627776 bytes you get using power-of-two.

Comment Re:"they" can fuck off, the binary units are the o (Score 5, Insightful) 618

None of what you are talking about has anything to do with what I said. I am talking about the measurement of things, not the things themselves.

Memory components are power-of-two boundaries in size. This is necessary because if they were other than a power-of-two in size, math would have to be performed on each memory access. For instance, if you had memory chips that were 1000 bytes in size, and you wanted to access byte 1024, you would have to perform a calculation to find that the byte is at location 24 in the second chip. With binary sizes however, all you need to do is use the address lines to directly access the correct location in the correct chip. Also note that the word-size of the data does not matter: you could return 1 bit, 8 bits, 10 bits, anything at all. What matters is that the number of 'things' (whatever size of the 'thing' itself is) is always a power of two.

Network speeds are not dependant in the slightest on a power-of-two, regardless of the data being transported. There is absolutely no reason to say that a network that can transfer 1024 bits per second is in any way better or more natural than one that can transfer 1000 bps or one that can transfer 1100 bps. There is no reason to assume that a 'kilobit per second' is anything other than 1000 bps. And if you change the measurement to count bytes instead of bits, a network can transfer 137.5 Bps as easily as it can transfer 1100 bps, or 1.1Kbps.

Hard disk sizes are like network speeds: there is no inherent power-of-two to their size. There is no reason why a disk could not be made to hold exactly 1000000 bytes (excluding the fact that you would have a partial sector). Therefore, trying to force some power-of-two based prefix on those sizes is just silly.

Slashdot Top Deals

Humanity has the stars in its future, and that future is too important to be lost under the burden of juvenile folly and ignorant superstition. - Isaac Asimov