1Mbps vs 1MBps...is there a difference???

[svidge]

As I'm shopping around for an uncapped ADSL I notice that the products' bandwidths are sold as xMbps and not xMBps.

According to my knowledge...if the "b" is in lower case then that means the b stands for bits not Bytes.

Example: 1Mbps = 125KBps

I hope I'm wrong.

 

[MKFrost]

Small b = bits and capital B = bytes

Mbps = Mega BITS per second / MBps = Mega BYTES per second

8 bits to a byte

so 1 Mbps = 1024 bits / 8 = 125 bytes or 0.125 MBps

 

[froot]

Networks are done in bits per second, iow bps, Kbps, Mbps, Gbps.

So with that reasoning, and your knowledge, 1Mbps is 125KBps.
However, due to overhead on TCP/IP, a 1Mbps line runs at about 104KB/s.

 

[froot]

Small b = bits and capital B = bytes

Mbps = Mega BITS per second / MBps = Mega BYTES per second

8 bits to a byte

so 1 Mbps = 1024 bits / 8 = 125 bytes or 0.125 MBps

Kilobytes. Not bytes

 

[Arthur]

MKFrost explains it well.

However, the reality is many who author websites, docs, spec sheets, etc don't know these conventions and so don't use them consistently.

You'll need to dig in for more detail and get them to spell it out in detail. Don't rely on little b being bits and big B being bytes. Neither are the SI prefixes always used correctly - and in any case they're not strictly SI when used in IT context.

Edit. Example: SI prefix for kilo is lowercase k. Capital K is Kelvin. So strictly speaking, kilobytes is kB. And kilobits is kb. But there's no international agreement on this, though signatories to SI must use lowercase k to denote kilo.

SI also requires you write Mb/s for megabits per second (not Mbps). Americans do not know this.

 

[svidge]

So if they say u get "up to" 1Mbps...u are looking @ a speed of less than 100KBps and lower??

 

[ponder]

Example: 1Mbps = 125KBps

I hope I'm wrong.

You are not wrong. Data communication speeds have always been measured in bits per second since the dawn of time and precede computers. The majority of comms are of a serial nature which means sending and receiving one bit at a time whereas a byte is some arbitrary value someone decided to assign to 8 bits.

 

[MKFrost]

So if they say u get "up to" 1Mbps...u are looking @ a speed of less than 100KBps and lower??

On a 1Mbps you should get in the region of 100/120 KBps. But as others have stated, there is overhead, your distance from the exchange and quality of the line if on ADSL etc...

The 'up to' is Telkom's way of covering themselves i.e. they cannot guarantee that your connection will run at 100% speed.

 

[Arthur]

Well said, ponder.

 

[MKFrost]

You are not wrong. Data communication speeds have always been measured in bits per second since the dawn of time and precede computers. The majority of comms are of a serial nature which means sending and receiving one bit at a time whereas a byte is some arbitrary value someone decided to assign to 8 bits.

True, was the reason for the 8 bits = 1 byte not due to the first processing chips that could only process 8 bits at a time?

 

[Arthur]

True, was the reason for the 8 bits = 1 byte not due to the first processing chips that could only process 8 bits at a time?

It arose because this was the smallest 'power of 2' string required to map to the common Latin alphabet (upper and lowercase), plus punctuation and control characters. ASCII was one of several agreed conventions to map alpha to binary (via hex, incidentally). Remember EBCDIC? Early devices such as terminals, printers and modems were often measured in characters per second (cps), not bps. Early comms systems used 7-bit character mapping, with 1 or 2 control and/or parity bits.

Speeds 'n feeds have of course increased somewhat since then. But it's all still bits, bytes and words underneath.

 

[svidge]

Now if someone says to me; "with the 1Mbps option you get bla bla bla and video streaming", should I hug them or spank them??

 

[froot]

Now if someone says to me; "with the 1Mbps option you get bla bla bla and video streaming", should I hug them or spank them??

Spank them. The closest you'll get to streaming with a 1Meg is 360p.

 

[Arthur]

Just to further illustrate the wrinkles and lack of common language:

kilo is the SI prefix for 10^3, ie 1000.

But in computerese, kilo denotes 1024 because of the way binary arithmetic works. One kilobyte = 1024 bits.

Mega is SI for 10^6, ie 1 000 000.

So, how many bits in a megabyte?

The answer is: it depends. Just speak to HDD makers and network makers. Though they use the same words, they often don't mean the exact same thing.

 

[Rickster]

100 Mb/s LAN is 10-12MB/s download

1 Gigabit LAN is *+-80MB/s


* Dependent on HDD RPM and network quality

 

[ponder]

True, was the reason for the 8 bits = 1 byte not due to the first processing chips that could only process 8 bits at a time?

Because it was the most common at the time,also involved the ascii table & EBCDIC. Prior to this you got 4 & 6 bit bytes as this was what the cpu's processed ie Intel 4004.

http://en.wikipedia.org/wiki/Byte#History

I recall assembly language on the 68k Amiga where you had bytes (8), words (16), long words (32)