Friday, May 18th, 2012

	The feeling of computing
	~~~~~~~~~~~~~~~~~~~~~~~~

The era, when mainframes were the only computers and spent their
lifeteime computing various tasks for long hours or even days, is for
most of people distant history. Computers, we have on our desks, can
do most of tasks in realtime or so fast, that it almost seems like
realtime. Maybe, if you process movie files or compile source code a
lot, you wish your computer would be a bit faster. But today even 
these tasks do not last for days to finish.

Because of the so called "Fair Use Policy", practised  by all czech
mobile operators (in my case 37.5 MB of data per week, then 16 kbit/s
limitation), online maps are quite unusable. I can waste my precious
FUP quota after an hour of using Google Maps, or use offline maps. So
I decided to go with the latter and create an offline map of Czech
Republic for my Android phone. There is app called Locus, which can
display offline maps in the form of calibrated bitmaps and Windows
application MapGen, which can create such butmaps from online sources.

So I installed Windows XP inside VirtualBox running on my white Core2
iMac, filled in proper coordinates, selected desired map layers and
maximal zoom and started the process. After about an hour MapGen
generated batch files: about 264000 map tiles will be requred. My
computer with my internet connection can download about 80 tiles per
minute at average. With just simple maths, that is 55 straight hours.
Then there will be format conversion, tagging with coordinates and in
the end the whole map will be stuffed inside single tar file. From my
previous experience with maps covering smaller areas, this will take
at least the same amount of time as downloading. So I have task that
will take at least 110hours to compute. 

I can't resist watching the console window with messages rolling since
last saturday. I am putting iMac to sleep every evening, because
I like it silent in my room during night. Now, after five days, 
the download is almost complete, just about last 5000 tiles need to be
downloaded. With some luck a week from now my map will be complete.

Yeah, that's the stuff: taking the most powerfull computer you have,
making it to do something for days or even weeks. Everybody should try
that time from time. "The feeling of computing" is really great, it's
like touching some long gone times. And it will help you realize, that
computers today are really fast. For most tasks, we want them to do.
.