6 bit things...

[server]

Is a byte always 8 bits? What can I call a 6-bit byte? A clump?

I want to send data over an SFP optical link, in 6-bit things.

0 1 1 0 d \\d repeated, roughly 100 Mbits/sec

is DC balanced, which SFP likes.

 

[Clive Arthur]

On 03/08/2022 16:52, jlarkin@highlandsniptechnology.com wrote:

Is a byte always 8 bits? What can I call a 6-bit byte? A clump?

I want to send data over an SFP optical link, in 6-bit things.

0 1 1 0 d \\d repeated, roughly 100 Mbits/sec

is DC balanced, which SFP likes.

The French (and maybe others) use \'octet\' for byte, so \'sextet\' sounds
reasonable.

I use \'nips\' for two bits, don\'t know if anyone else does.

--
Cheers
Clive

 

[Martin Rid]

jlarkin@highlandsniptechnology.com Wrote in message:r
> Is a byte always 8 bits? What can I call a 6-bit byte? A clump?I want to send data over an SFP optical link, in 6-bit things. 0 1 1 0 d \\d repeated, roughly 100 Mbits/secis DC balanced, which SFP likes.

I would still consider it a byte, but sixbit.
You could always call it braille.

Cheers
--


----Android NewsGroup Reader----
https://piaohong.s3-us-west-2.amazonaws.com/usenet/index.html

 

[server]

On Wed, 3 Aug 2022 12:03:11 -0400 (EDT), Martin Rid
<martin_riddle@verison.net> wrote:

jlarkin@highlandsniptechnology.com Wrote in message:r
Is a byte always 8 bits? What can I call a 6-bit byte? A clump?I want to send data over an SFP optical link, in 6-bit things. 0 1 1 0 d \\d repeated, roughly 100 Mbits/secis DC balanced, which SFP likes.

I would still consider it a byte, but sixbit.
You could always call it braille.

Cheers

Maybe \"frame\" sounds better than \"clump.\"

 

[Joe Gwinn]

On Wed, 03 Aug 2022 08:52:08 -0700, jlarkin@highlandsniptechnology.com
wrote:

>Is a byte always 8 bits? What can I call a 6-bit byte? A clump?

It would still be a byte. Univac 1108, with 36-bit words.

A byte was always a fraction of a word, but the length of a word was
whatever the computer was designed for. All sizes were tried.

I\'ve worked on digital computers with the following word sizes (in
bits): 12, 16, 24, 32, 36, 48, 64.

There were just as many floating-point formats.

Now days, it has settled down, and words are multiples of 8 bits in
size, usually a power of two. And all FP is IEEE.

The standards folk came up with \"octet\" because byte was so
ill-defined.

Half an octet was sometimes called a nybble. And so on.

I want to send data over an SFP optical link, in 6-bit things.

0 1 1 0 d \\d repeated, roughly 100 Mbits/sec

is DC balanced, which SFP likes.

If you use 8-bit patterns (best for component availability), but use
only the DC balanced subset, does that suffice?

Or, turn it around. Figure out how many DC-balanced patterns you
need, double it (for growth), and figure out long a word is needed.
Don\'t forget to include some control patterns.

Gigabit Ethernet does something like this, only grander, with two
patterns for every possible symbol to be sent, and they track current
DC balance, and choose which pattern to use that will reduce the
running DC balance.

Joe Gwinn

 

[Dan Purgert]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

jlarkin@highlandsniptechnology.com wrote:
> Is a byte always 8 bits? What can I call a 6-bit byte? A clump?

As of sometime in the early-mid 1990s (\'94?), \"Byte\" is 8 bits.
Historically, different terms were used (\"word\" , \"syllable\", etc.), and
represented some contiguous set of bits that wasn\'t necessarily 8 -- for
example 6, 12, or 18 bits. As far as I am aware, these were not
industry-standard terms, and therefore the bit-width would vary between
vendors.

As far as I am aware, the only modern subdivisions of a Byte are

- bit (1/8 Byte)
- nybble (1/2 Byte)

There\'s probably some ISO standard document somewhere that defines all
of this these days.

I want to send data over an SFP optical link, in 6-bit things.

0 1 1 0 d \\d repeated, roughly 100 Mbits/sec

is DC balanced, which SFP likes.

It is my understanding that an SFP tranceiver is somewhat akin to an
RS485 tranceiver, in that it doesn\'t particularly \"care\" about what
you\'re kicking out \"over the wire\". Rather, it is up to the
sending/receiving party to agree on a protocol for the data framing.

That being said; I\'m mainly familiar with their use in IEEE 802.3
(Ethernet) networking, and not really outside of that context; so take
the above with a grain of salt.

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--
|_|O|_|
|_|_|O| Github: https://github.com/dpurgert
|O|O|O| PGP: DDAB 23FB 19FA 7D85 1CC1 E067 6D65 70E5 4CE7 2860

 

[John Walliker]

On Wednesday, 3 August 2022 at 17:15:04 UTC+1, jla...@highlandsniptechnology.com wrote:

On Wed, 3 Aug 2022 12:03:11 -0400 (EDT), Martin Rid
martin...@verison.net> wrote:

jla...@highlandsniptechnology.com Wrote in message:r
Is a byte always 8 bits? What can I call a 6-bit byte? A clump?I want to send data over an SFP optical link, in 6-bit things. 0 1 1 0 d \\d repeated, roughly 100 Mbits/secis DC balanced, which SFP likes.

I would still consider it a byte, but sixbit.
You could always call it braille.

Cheers
Maybe \"frame\" sounds better than \"clump.\"

From https://en.wikipedia.org/wiki/Byte

The size of the byte has historically been hardware-dependent and no definitive standards existed that
mandated the size. Sizes from 1 to 48 bits have been used.[4][5][6][7] The six-bit character code was an
often-used implementation in early encoding systems, and computers using six-bit and nine-bit bytes
were common in the 1960s. These systems often had memory words of 12, 18, 24, 30, 36, 48, or 60 bits,
corresponding to 2, 3, 4, 5, 6, 8, or 10 six-bit bytes. In this era, bit groupings in the instruction stream were
often referred to as syllables[a] or slab, before the term byte became common.

I also like the sound of sextet. Its easy to say out loud and gives a strong hint at the meaning.

John

 

[John Walliker]

On Wednesday, 3 August 2022 at 17:52:04 UTC+1, Dan Purgert wrote:

I want to send data over an SFP optical link, in 6-bit things.

0 1 1 0 d \\d repeated, roughly 100 Mbits/sec

is DC balanced, which SFP likes.
It is my understanding that an SFP tranceiver is somewhat akin to an
RS485 tranceiver, in that it doesn\'t particularly \"care\" about what
you\'re kicking out \"over the wire\". Rather, it is up to the
sending/receiving party to agree on a protocol for the data framing.

SFP transceivers are capacitor coupled on input and output so they do
care about the dc balance of the signal. I believe that there is also
capacitor coupling in the photodetector circuit. They don\'t care about
the exact protocol however.

John

 

[Dimiter_Popoff]

On 8/3/2022 18:58, Clive Arthur wrote:

On 03/08/2022 16:52, jlarkin@highlandsniptechnology.com wrote:
Is a byte always 8 bits? What can I call a 6-bit byte? A clump?

I want to send data over an SFP optical link, in 6-bit things.

    0 1 1 0 d \\d   repeated, roughly 100 Mbits/sec

is DC balanced, which SFP likes.


The French (and maybe others) use \'octet\' for byte, so \'sextet\' sounds
reasonable.

I use \'nips\' for two bits, don\'t know if anyone else does.

And others indeed. All the RFC-s I have read use \"octet\", apparently
a byte has not always been used meaning 8 bits. So the IETF have taken
the decision quite a while ago.

I\'d go with \"sextet\", although since during programming it will
typically be part of a byte I\'d comment \"lowest 6 bits\" or something.

 

[John Larkin]

On Wed, 03 Aug 2022 12:35:16 -0400, Joe Gwinn <joegwinn@comcast.net>
wrote:

On Wed, 03 Aug 2022 08:52:08 -0700, jlarkin@highlandsniptechnology.com
wrote:

Is a byte always 8 bits? What can I call a 6-bit byte? A clump?

It would still be a byte. Univac 1108, with 36-bit words.

A byte was always a fraction of a word, but the length of a word was
whatever the computer was designed for. All sizes were tried.

I\'ve worked on digital computers with the following word sizes (in
bits): 12, 16, 24, 32, 36, 48, 64.

There were just as many floating-point formats.

Now days, it has settled down, and words are multiples of 8 bits in
size, usually a power of two. And all FP is IEEE.

The standards folk came up with \"octet\" because byte was so
ill-defined.

Half an octet was sometimes called a nybble. And so on.


I want to send data over an SFP optical link, in 6-bit things.

0 1 1 0 d \\d repeated, roughly 100 Mbits/sec

is DC balanced, which SFP likes.

If you use 8-bit patterns (best for component availability), but use
only the DC balanced subset, does that suffice?

We could do 8b10b, but that would need an FPGA to generate and
receive. I\'m thinking about a spare-time thing that I could design
without an FPGA or uP, all hardware. My digital people are swamped
with big projects and I need something fun to design.

Or, turn it around. Figure out how many DC-balanced patterns you
need, double it (for growth), and figure out long a word is needed.
Don\'t forget to include some control patterns.

The data is a 1-bit steam from a delta-sigma ADC. I just want to
transport it over fiber, and SFP is the easy way to do that. But SFP
is intended for telecom, ac coupled, intolerant of dc imbalance. Most
SFPs won\'t pass anything below about 1 MHz. But they are crazy fast
and have great AGC.

Gigabit Ethernet does something like this, only grander, with two
patterns for every possible symbol to be sent, and they track current
DC balance, and choose which pattern to use that will reduce the
running DC balance.

8b10b does elaborate long-term DC balancing like that. Too much work.

SFPs usually tolerate a little DC imbalance. You can send PWM at, say,
35% to 65%.

Joe Gwinn

 

[Fred Bloggs]

On Wednesday, August 3, 2022 at 11:52:21 AM UTC-4, jla...@highlandsniptechnology.com wrote:

Is a byte always 8 bits? What can I call a 6-bit byte? A clump?

I want to send data over an SFP optical link, in 6-bit things.

0 1 1 0 d \\d repeated, roughly 100 Mbits/sec

is DC balanced, which SFP likes.

It\'s a hexad.

 

[Phil Hobbs]

jlarkin@highlandsniptechnology.com wrote:

On Wed, 3 Aug 2022 12:03:11 -0400 (EDT), Martin Rid
martin_riddle@verison.net> wrote:

jlarkin@highlandsniptechnology.com Wrote in message:r
Is a byte always 8 bits? What can I call a 6-bit byte? A clump?I want to send data over an SFP optical link, in 6-bit things. 0 1 1 0 d \\d repeated, roughly 100 Mbits/secis DC balanced, which SFP likes.

I would still consider it a byte, but sixbit.
You could always call it braille.

Cheers

Maybe \"frame\" sounds better than \"clump.\"

Or \'clod\'. Alternatives abound.

I\'d go with sextet (or sestet, if you\'re feeling poetic).

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[John Walliker]

On Wednesday, 3 August 2022 at 21:09:20 UTC+1, Cydrome Leader wrote:

jla...@highlandsniptechnology.com wrote:
Is a byte always 8 bits? What can I call a 6-bit byte? A clump?

I want to send data over an SFP optical link, in 6-bit things.

0 1 1 0 d \\d repeated, roughly 100 Mbits/sec

is DC balanced, which SFP likes.
six bit word.

After all this discussion it occurs to me that the correct answer is a bit.
The 0110 is a dc balanced header and the d \\d is just a coding scheme
that ensures dc balance without conveying more than 1 bit of information.

John

 

[John Larkin]

On Wed, 3 Aug 2022 16:07:04 -0400 (EDT), Martin Rid
<martin_riddle@verison.net> wrote:

jlarkin@highlandsniptechnology.com Wrote in message:r
On Wed, 3 Aug 2022 12:03:11 -0400 (EDT), Martin Rid<martin_riddle@verison.net> wrote:>jlarkin@highlandsniptechnology.com Wrote in message:r>> Is a byte always 8 bits? What can I call a 6-bit byte? A clump?I want to send data over an SFP optical link, in 6-bit things. 0 1 1 0 d \\d repeated, roughly 100 Mbits/secis DC balanced, which SFP likes.>>I would still consider it a byte, but sixbit.>You could always call it braille. >>CheersMaybe \"frame\" sounds better than \"clump.\"

Sixbit packet
And call it a day.

Cheers

Sixpack.

 

[Martin Rid]

jlarkin@highlandsniptechnology.com Wrote in message:r
> On Wed, 3 Aug 2022 12:03:11 -0400 (EDT), Martin Rid<martin_riddle@verison.net> wrote:>jlarkin@highlandsniptechnology.com Wrote in message:r>> Is a byte always 8 bits? What can I call a 6-bit byte? A clump?I want to send data over an SFP optical link, in 6-bit things. 0 1 1 0 d \\d repeated, roughly 100 Mbits/secis DC balanced, which SFP likes.>>I would still consider it a byte, but sixbit.>You could always call it braille. >>CheersMaybe \"frame\" sounds better than \"clump.\"

Sixbit packet
And call it a day.

Cheers
--


----Android NewsGroup Reader----
https://piaohong.s3-us-west-2.amazonaws.com/usenet/index.html

 

[Cydrome Leader]

jlarkin@highlandsniptechnology.com wrote:

Is a byte always 8 bits? What can I call a 6-bit byte? A clump?

I want to send data over an SFP optical link, in 6-bit things.

0 1 1 0 d \\d repeated, roughly 100 Mbits/sec

is DC balanced, which SFP likes.

six bit word.

 

[John Larkin]

On Wed, 3 Aug 2022 14:28:30 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Wed, 3 Aug 2022 12:03:11 -0400 (EDT), Martin Rid
martin_riddle@verison.net> wrote:

jlarkin@highlandsniptechnology.com Wrote in message:r
Is a byte always 8 bits? What can I call a 6-bit byte? A clump?I want to send data over an SFP optical link, in 6-bit things. 0 1 1 0 d \\d repeated, roughly 100 Mbits/secis DC balanced, which SFP likes.

I would still consider it a byte, but sixbit.
You could always call it braille.

Cheers

Maybe \"frame\" sounds better than \"clump.\"



Or \'clod\'. Alternatives abound.

I\'d go with sextet (or sestet, if you\'re feeling poetic).

Cheers

Phil Hobbs

Now one of my guys claims that all we need is

1 0 d1 \\d1 1 0 d2 \\d2 .... etc

four bits per chunk to recover data d. Which is a nibble. I can still
call each 4 bits a frame.

I hate it when people are smarter than I am.

 

[Joe Gwinn]

On Wed, 03 Aug 2022 10:19:49 -0700, John Larkin
<jlarkin@highland_atwork_technology.com> wrote:

On Wed, 03 Aug 2022 12:35:16 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:

On Wed, 03 Aug 2022 08:52:08 -0700, jlarkin@highlandsniptechnology.com
wrote:

Is a byte always 8 bits? What can I call a 6-bit byte? A clump?

It would still be a byte. Univac 1108, with 36-bit words.

A byte was always a fraction of a word, but the length of a word was
whatever the computer was designed for. All sizes were tried.

I\'ve worked on digital computers with the following word sizes (in
bits): 12, 16, 24, 32, 36, 48, 64.

There were just as many floating-point formats.

Now days, it has settled down, and words are multiples of 8 bits in
size, usually a power of two. And all FP is IEEE.

The standards folk came up with \"octet\" because byte was so
ill-defined.

Half an octet was sometimes called a nybble. And so on.


I want to send data over an SFP optical link, in 6-bit things.

0 1 1 0 d \\d repeated, roughly 100 Mbits/sec

is DC balanced, which SFP likes.

If you use 8-bit patterns (best for component availability), but use
only the DC balanced subset, does that suffice?

We could do 8b10b, but that would need an FPGA to generate and
receive. I\'m thinking about a spare-time thing that I could design
without an FPGA or uP, all hardware. My digital people are swamped
with big projects and I need something fun to design.


Or, turn it around. Figure out how many DC-balanced patterns you
need, double it (for growth), and figure out long a word is needed.
Don\'t forget to include some control patterns.


The data is a 1-bit steam from a delta-sigma ADC. I just want to
transport it over fiber, and SFP is the easy way to do that. But SFP
is intended for telecom, ac coupled, intolerant of dc imbalance. Most
SFPs won\'t pass anything below about 1 MHz. But they are crazy fast
and have great AGC.

Is it 100 million bits per second, or symbols per second?

What is being digitized? Voice? Data of some kind?

Is there a maximum latency and latency jitter requirement?

One-bit delta samples are usually signed, so the minimum is two
symbols. If the voltage being sent is zero, then we\'ll get a steady
+,-,+,-,+, stream, which will have very strong RF spurs and thus
emissions, so need to break this up.

A zero symbol makes it three, and an idle symbol, makes it four
symbols.

Gigabit Ethernet does something like this, only grander, with two
patterns for every possible symbol to be sent, and they track current
DC balance, and choose which pattern to use that will reduce the
running DC balance.

8b10b does elaborate long-term DC balancing like that. Too much work.

SFPs usually tolerate a little DC imbalance. You can send PWM at, say,
35% to 65%.

Yes, too much trouble. But if you use table lookup, you can get close
enough.

For instance, have four tables (one per symbol), with unique random
patterns, and choose a pattern from the correct table for the symbol
to be sent. These patterns are all inherently DC balanced, being half
+ and half -, and don\'t have any long runs.

On the receive end, use table lookup to recover the sent symbols.

You will need a sync pattern to establish and maintain symbol framing.
The key property of sync patterns is a sharp single correlation peak
against shifted examples of that pattern. A sync preamble may be
multiple sync symbols concatenated. Sync and idle symbols may be the
same.


Joe Gwinn

 

[Martin Brown]

On 03/08/2022 21:09, Cydrome Leader wrote:

jlarkin@highlandsniptechnology.com wrote:
Is a byte always 8 bits? What can I call a 6-bit byte? A clump?

I want to send data over an SFP optical link, in 6-bit things.

0 1 1 0 d \\d repeated, roughly 100 Mbits/sec

is DC balanced, which SFP likes.

six bit word.

MIX - for the model 1009 Knuth polyunsaturated virtual computer used 6
bit bytes and 5 bytes to a word in TAOCP. It was partly intended to
break any algorithm that relied on things being a handy power of two.


--
Regards,
Martin Brown

 

[John Walliker]

On Wednesday, 3 August 2022 at 21:52:50 UTC+1, Martin Brown wrote:

On 03/08/2022 21:09, Cydrome Leader wrote:
jla...@highlandsniptechnology.com wrote:
Is a byte always 8 bits? What can I call a 6-bit byte? A clump?

I want to send data over an SFP optical link, in 6-bit things.

0 1 1 0 d \\d repeated, roughly 100 Mbits/sec

is DC balanced, which SFP likes.

six bit word.
MIX - for the model 1009 Knuth polyunsaturated virtual computer used 6
bit bytes and 5 bytes to a word in TAOCP. It was partly intended to
break any algorithm that relied on things being a handy power of two.

I never had enough bookshelf space - or money at the time - for the complete
works of Knuth. I don\'t know how he managed to do so much!

John