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Thursday, April 24, 2014

On Kilobytes, Megabytes, and other computer-centric factors

I started programming way back.  In those olden days I was working close to the machine - on machine language stuff (assembly languages).  Bits were important: shift left, shift right, AND/OR/XOR.  And memory pages were important too: fitting an important routine within a 256 byte page could really help performance.

These days life is different.  You allocate objects.  If you're storing a boolean, you create a boolean object.  Who knows how that's represented under the hood, but it certainly isn't represented in one bit of RAM.   Most people don't even use the bitwise operators offered through the programming languages given to them.  Sure, some do.  But most do not.

And so now we get into our prefixes: kilo, mega, giga, terra, and peta (and beyond, I suppose!)

Many people still want these prefixes to be based on powers of 2.  One kilobyte is 1024 bytes (2^10). One megabyte is 1024*1024 bytes (2^20).  Etc.  It's an OK system, but it really makes little sense. Why is a kilobyte 2^10?  Because the number, when converted to decimal, is the power-of-two  number that's closest to 1,000.  2^11 and 2^9 simply aren't as close to 1000 as 2^10.

Anyhow, all this mades some (but not much) sense in terms of RAM addressing.  Then people wanted disks to work the same way, so disk sectors were often 256 or 512 bytes large - not due to any physical or logical requirement, mind you, but because it was brain-dead easy to put a page of RAM into a sector.  Again, performance at 1 MHz ruled the day (that M, oddly, means exactly "1,000,000")

At the same time the network guys were not interested in this "new math".  They did things in bits per second.  Bytes?  No way!  That was 8 bits, or an octet.  kilo?  That meant 1000.  Nothing else.  Mega?  1,000,000.    100 Megabits per second meant 100,000,000 megabits in one second. And it still does to a network guy.

But then the uncultured programmers got in there and confused everyone.  They started to apply their terminology to other areas for NO REASON.   What does 100 MB/second mean?  WHO THE FUCK KNOWS!

The disk drive guys got yelled at for NOT using the stupid convention.  Dumbo programmers wanted 1 GB of storage to mean 1024 * 1024 *1024.  Why?  Because it was bigger!

Let's say you are dumping 1 billion records onto a disk.  Each record is 40 bytes long.  Quick, do you have enough room if you have 38.1 GB free?  WHO KNOWS!  Because bonehead programmers confused everyone.

It's time to give up the obsolete base-2 notion of kilo, mega, and giga.  If you really love powers of two, use them explicitly like a REAL tech expert.  My laptop has 2^33 bytes of RAM.  Done.  And now how many pages of RAM is that?  Simple math.



Sunday, March 09, 2014

A Calendar for Everyone

We all kind of dislike calendars that we aren't accustom to, and tons of folks over the centuries have thought they could do a better job.  And some people around the world see calendars as being a primarily religious instrument since Pope Gregory XIII's people pushed for the one we use today.

Here's my proposal, which combines the Herschel and a modified Holocene calendar.
  • Take on the proposal of Sir John Herschel, so that there are 969 leap days every 4000 years.
  • Take on the concept of the Holocene calendar year numbering system, but modify it as such: 
    • The year number is an aggregate of the top 30 year numbers of the calendars of the world, modulo 100.  Then add 10,000.  My calculation comes up with the year 10043.  For you Gregorian fans, just subtract 8029.
  • Retain the other structures of the Gregorian/Julian calendaring system, notably: month numbering, month length, weekdays.
  • Call this the Earth Solar Calendar.
Result:
  • A calendar that is not the Gregorian calendar
  • A calendar that is generally compatible with the Gregorian calendar for all practical purposes
  • A calendar with a new year style which clearly identifies itself from other commonly used calendar styles
  • A calendar that is generally not affiliated with any specific religion or society
Concerns:
  • The proposed calendar retains the Gregorian correction to the Julian calendar.  The timing of that reform is tied to a religious event.
  • The calendar retains the month model of the Julian calendar.
  • Those that appreciate the supposed linkage of the Gregorian calendar with religion may be unhappy with the proposal.  However, the Gregorian calendar is a weird hodgepodge of lunar and solar calendars with a stem several thousand years older than the current Gregorian calendar year. Furthermore, the Gregorian year number is widely known to be inaccurate.
  • No one likes change.

My Computer Security Failures

I'm a security-concious guy, but I have screwed up before.  Here are my security failures over time that I know about:


1994: I downloaded and executed a program from the Internet.  The program spun through the Windows 3.11-based system, overwriting all files.  This resulted in significant data loss.

Root cause: User trusted untrustworthy software.  User failed to back up system.


2001: Fell victim to an SSH exploit on my Linux-based router machine.  The machine was compromised by a remote attacker and used to send spam.  The machine needed to be wiped and reloaded.

Root cause: Zero-day exploit vulnerability, and/or failure to keep on top of security patches.


2006: I gave administrative rights to my brother's au pair's Windows XP-based PC, under pressure from the au-pair who wanted to install software.  The machine was quickly overwhelmed by malware despite anti-virus practices.  The machine was kept in service after significant cleanup.

Root cause: The platform assumed users would need powerful privileges; administrator inappropriately complied.


2008: My account at a popular Internet Service, Twitter, was compromised and misused.

Root cause: I followed poor password management practices: I re-used an identical username/password pair with multiple service providers for accounts "I didn't care about".


2008: Unprivileged Mac OS X user account was compromised remotely over SSH via brute force, due to simple username and matching simple password.

Root cause: Administrator enabled remote SSH access but failed to restrict ssh access to specific accounts.


2014: Wireless access point unsecured, resulting in open network access over-the-air.

Root cause: Administrator created a second wireless SSID without properly securing it.

Sunday, March 02, 2014

Save big money with Free WIFI?

Who wants to pay for Internet?  Maybe your neighbor has open WIFI!  Freedom!  FREE!!!

The problem is that your neighbor's WIFI should never be trusted.  Here's what your neighbor could find out about you:
  • Who you are
  • What sites you visit
  • Your daily schedule
  • What kind of devices you use
  • Probe your devices for vulnerabilities
  • Read many of the web pages you read as you read them
  • See how much mail you receive and send
  • Manipulate what you read on the internet
Now don't be surprised - your ISP can do these things too.  But at least your ISP has a reputation to uphold and (weak) regulations that they must legally conform to.  Your anonymous neighbor that you're stealing from?  They don't really have to worry about such things.

If you're going to steal Internet, use VPN.  VPN doesn't solve all problems, but it solves some of them.

Friday, January 03, 2014

Fixing my Wahl 9918 Groomsman Beard and Mustache Trimmer

Not everyone would bother repairing a $20 beard trimmer, but why not fix something for under $5 instead of spending another $20?

My Wahl 9918 Groomsman Beard and Mustache Trimmer has admirably performed its beauty duty for many years, but the time came when the battery just wasn't holding a charge any more.  Most people would just put the trimmer in the trash and buy a new one, but I figured I could repair my Wahl and save some money.

I opened up the Wahl by popping off the black plastic faceplate with a tiny flathead screwdriver, which revealed two screws.  By removing the two screws I was able to easily open up the unit, revealing the guts of the device.


Backplate off, Revealing the screws


The internals are rather simple: a motor, a simple circuit board, a switch, and a NiCad battery pack soldered into place.
The Internals, with new battery pack

I decided that the battery was no longer good, so I worked to replace it.  I bought two NiCd Extended Capacity Rechargeable AA Cells with Solder Tab.  The solder tabs are key - they make it reasonably possible to solder together a new battery pack.

To create a new battery pack, I used some electrical tape to wrap together the two new cells, in plus-to-minus orientation.  Then I used a trusty soldering iron to solder one of the plus/minus tables together.  I pulled the foam off the old battery pack and stuck it onto my homemade pack.

Then I unsoldered the old battery pack from the Wahl and soldered the new pack in, ensuring that I kept proper polarity.

After, I cleaned up some corrosion on the switch with a pencil eraser and an emery board, and reassembled.  A little test proved good, and so I plugged in the trimmer and let it charge overnight.

Now the Wahl works like new! It runs perfectly and charges perfectly to.  It continues to provide me with a beautiful beard, nearly 10 years running.

Sunday, December 15, 2013

Unlocking the Verizon iPhone 4S - MD278LL/A

Before you buy that unlocked Verizon iPhone 4S, you might want to read this.

After considerable research, I conclude that Verizon's "unlocking" program does not actually unlock the iPhone 4S.

Instead, Verizon's program seems to merely bless specific non-American 3rd party SIMs to be used with your iPhone.  It looks like American 3rd party SIMs from AT&T and T-Mobile USA are locked out forever even after the Verizon "Unlock".

In fact, within Apple's "Wireless carrier support and features" knowledge base article ht1937, Apple itself says that Verizon "offers unlocking on certain iPhones, some with certain restrictions."

That's certainly ominous.  It reads like Verizon might be willing to unlock the deadbolt on your iPhone, but the security chain is still attached so only some SIMs through.  To me, that isn't an unlock.  That's a lock with exceptions.

Do you want to use an AT&T or T-MobileUSA SIM in your Verizon iPhone?  That's Verizon's choice.  And from everything I understand, Verizon will say "no" - they will not unlock the SIM for these carriers.  Your iPhone is still locked.

Even though its your phone.

And you paid for it in full.

And you've been a good customer for years.

And the device has all the technology it needs.

Maybe the best way out is to sell your old iPhone 4S and get yourself a brand new, inexpensive "contract" smartphone like this inexpensive Nokia on T-Mobile.  Or go all out and get an unlocked Apple iPhone 5S.

Saturday, December 07, 2013

Do WIFI security cameras work? This EasyN one works for me!

I bought an inexpensive WIFI security camera - an "EasyN F-M166" - for my vacation home.

Does it work?  Well, yes it works very well!

Via a web browser on my Mac, I can view video, tilt-and-pan the camera, and control things like the infrared lighting.   It doesn't need any special software or plug-ins for my Mac, and I can even view the thing from my iPhone.

My EasyN WIFI cam, mounted upside-down on my porch ceiling

I have the camera mounted outside, in a protected area of my porch.  I'm not sure if it'll survive cold weather, but it still works OK even though it has been as cold as 15° F.  After a power failure it reconnects to WIFI just fine, so I don't have to worry too much about it getting disconnected from the Internet.

Via a web browser on my Mac, I can view video, tilt-and-pan the camera, and control things like the infrared lighting.   It doesn't need any special software for my Mac, and I can even view the thing from my iPhone.

Surveillance of a doorbell-pusher via the EasyN - as seen from my iPhone

With the camera's built-in web software, I've configured it to email me pictures every time "movement" is detected.  So I don't actually need a web browser to use the cam - I just get email with photos attached whenever anyone shows up at the house.  I -love- this feature.  Once in a while I'll get a moth or a bird or something, but that's the price you pay. Although the camera's web software is pretty ugly, it works very well; the software hasn't crashed yet despite running for the past 6+ months.

The camera sensor isn't nearly as good as a "real" camera, but I'm still very happy with it.    I haven't gotten the microphone to work on it, but I don't use it that way.

For under $50, it's a pretty darn good security camera.  You can find the EasyN F-M166 on Amazon.