technik – Page 2 – Technikal Mind

Transitions!

Posted on January 22, 2015 - May 27, 2022 by technik

Welcome to the new phase of Technikal Mind! Previously, TM included topics such as psychology, philosophy and more. I love exploring and discussing a variety of interests — the natural result of being curious — so I have split the project into technical and non-technical content. All of the content once hosted here has been transferred to Curious Thinker, which is dedicated to all other interests and covers more polymath/autodidact content.

Here at Technikal Mind, you’ll find anything technical in nature: computers, operating systems, programming/scripting, general technology, electronics, perhaps even a bit of gaming!

So stay tuned to either one if you wish to join me in the journey of curiosity.

Linux Runlevels

Posted on January 8, 2015 - May 27, 2022 by technik

Here is a general run down of Linux runlevels:

Runlevel	Description
0	Halt
1	Single-user mode
2	Basic multi-user mode (without networking)
3	Full (text based) multi-user mode
4	Not used
5	Full (GUI based) multi-user mode
6	Reboot

Ethernet Cabling

Posted on January 2, 2015 - May 27, 2022 by technik

Sometimes the naming scheme for Ethernet cabling standards can be a little confusing. The BASE in ####BASE-AA stands for baseband. The numbers and letters are explained thusly:

The first letter tells us which kind of wire we are talking about:
“T” means twisted-pair cable (e.g. the common Cat5 in use today)
“K” means a copper backplane
“C” means balanced copper cable
“F” means optical cable
“B” uses two wavelengths over a single optical cable
“S” means short-range multi-mode optical cable (less than 100 m)
“L” means long-range single- or multi-mode optical cable (100 m to 10 km)
“E” means extended-range optical cable (10 km to 40 km)
“Z” means long-range single-mode cable at a higher wavelength

Next is the coding scheme for data on the wire
“X” means 4B/5B block coding for Fast Ethernet or 8B/10B block coding for Gigabit Ethernet
“R” means 64B/66B block coding

Finally, we have a number representing the number of parallel “lanes” for data
“1” would mean serial (non-parallel) but is omitted instead
“4” or “10” are available for copper wire
Just about any other number could be used for optical lanes or wavelengths

Source

Here’s a chart of Ethernet cabling standards:

Ethernet Standard	Media Type	Bandwidth Capacity	Distance Limitation
10BASE5	Coax (thicknet)	10 Mbps	500 m
10BASE2	Coax (thinnet)	10 Mbps	185 m
10BASE-T	Cat 3 (or higher) UTP	10 Mbps	100 m
100BASE-TX	Cat 5 (or higher) UTP	100 Mbps	100 m
100BASE-FX	MMF	100 Mbps	2 km
1000BASE-T	Cat 5e (or higher) UTP	1 Gbps	100 m
1000BASE-TX	Cat 6 (or higher) UTP	1 Gbps	100 m
1000BASE-LX	MMF/SMF	1 Gbps/1 Gbps	5 km
1000BASE-LH	SMF	1 Gbps	10 km
1000BASE-ZX	SMF	1 Gbps	70 km
10GBASE-SR	MMF	10 Gbps	26–82 m
10GBASE-LR	SMF	10 Gbps	25 km
10GBASE-ER	SMF	10 Gbps	40 km
10GBASE-SW	MMF	10 Gbps	300 m
10GBASE-LW	SMF	10 Gbps	10 km
10GBASE-EW	SMF	10 Gbps	40 km
10GBASE-T	Cat 6a (or higher) UTP	10 Gbps	100 m
100GBASE-SR10	MMF	100 Gbps	125 m
100GBASE-LR4	SMF	100 Gbps	10 km
100GBASE-ER4	SMF	100 Gbps	40 km

Code: The Hidden Language of Computer Hardware and Software

Posted on January 2, 2015 - May 27, 2022 by technik

My lovely girlfriend surprised me with a copy of Code: The Hidden Language of Computer Hardware and Software for Christmas! I’ve been reading it over the past week or so, and have really enjoyed it.

It’s very similar in scope to Nand2Tetris, but with more of a guided tour through the nuanced history of computing. It starts by discussing the logical structure of codes such as product codes (UPC), Morse code, and Braille. Then it moves into a study of basic electrical circuits and eventually into building a calculator (well, a theoretical one, at least – it’s much too large to physically build).

Overall, it has been a great read thus far and I look forward to finishing it.

iptables Quick Reference

Posted on November 1, 2014 - May 27, 2022 by technik

This is a quick reference chart for iptables for the switches I use most commonly. For more information, see the man pages or use the --help switch.

-n (numeric output) -v (verbose output) --line-numbers (lists line numbers for use with -D) -D [chain] [line-number] (deletes line-number from chain) -N (creates a new chain)


add tcp 27014 to INPUT chain and ACCEPT

iptables -A INPUT -p tcp --dport 27014 -j ACCEPT

create new chain; add to INPUT

iptables -N NewChain
iptables -I INPUT -j NewChain

LED Infinity Mirror

Posted on August 15, 2014 - May 27, 2022 by technik

On my ever-lengthening list of Cool Tech Projects is … the Infinity Mirror.

The hunger for knowledge

Posted on May 19, 2013 - May 27, 2022 by technik

There are those who starve for truth and knowledge, and so seek it out.

Then there are those who starve, but do not attempt to sort out the good information from the bad.

The third and most unfortunate case, however, are those who do not even hunger for it.

Never stop being hungry.

Reservoir of billions-year-old water discovered

Posted on May 16, 2013 by technik

Working about a mile and a half under the surface in a deep Ontario mine, a team of scientists have discovered a pocket of water which they estimate to have been trapped underground for more than a billion years! It is unknown if any microbial life has been residing in the water all this time, but the right gasses to support life – methane and hydrogen – have been found. Through analysis, the scientists determined the fluids have not made contact with the Earth’s atmosphere for at least a billion years.

An important implication of this finding is on Mars. The surface of Mars is known to have contained water at one point in its past, and the rocks are chemical similar to Earth rocks. While the idea is entirely speculative at this point, microbial life may exist on Mars in these type of underground caves or reservoirs.

Source: http://www.nature.com/news/reservoir-deep-under-ontario-holds-billion-year-old-water-1.12995