My contribution to the increasing entropy, and eventual heat death of the universe
Archive for February 2012
It’s the year 2012 and this is the only way to get a legitimate digital copy of the seminal work in Computer Science, The Art of Computer Programming:
Shame really, let face it we pretty much know there’s a postscript file sitting on Donald Knuth’s PC somewhere…
I found a MFC-5895CW in Ryman’s today, discounted to 95 pounds. The MFC-5895CW is a multifunction printer/scanner/fax machine. What attracted me though is that it has a document feeder for scanning. I’ve been looking for a way to scan in my books (even if the process is destructive). As an aside, I’m told that book scanning services are common (and cheap) in Japan, it’s a shame it’s such a pain to get them there…
For my first effort I decided to use a book I was planning to throw out anyway “Digital System Design with VHDL” by Mark Zwolinski (sorry Mark, you were a great lecturer but I just don’t find myself doing much VHDL these days…).
To start with, I removed the front and back cover.
I then cut along the spine using a Stanley Knife:
Unfortunately, as I cut into the book I seem to have moved the knife nearer to the spine (something to avoid next time).
After slicing the whole thing up, it’s ready to scan!
The scanner can cope with about 60pages at a time. However it’s not a duplexing scanner. So once you’ve scanned one side you need to reinsert the stack of pages to scan the other side.
The MFC-5895CV scans directly to pdf. It creates files with a basename followed by a two digit number (01,02,03 etc.). It will also scan directly to a USB stick, which is rather neat.
So, after scanning you’re felt with a series of pdf files on a USB stick. Odd and Even numbered files form a pair of front and back sides of pages. You now need to join all these together.
I used pdftk on Linux to do this. Here’s my bash script (you’ll probably need to change the basename if you use it). It assumes it’s being run in the same directory as the input files.
basename="010111" for ((i=1; i<=99; i++)) do mkdir join cd join file1=../$basename`printf "%02d" $i`.PDF fileout=../$basename`printf "%02d" $i`join.pdf i=$((i+1)) file2=../$basename`printf "%02d" $i`.PDF echo "file1: " $file1 echo "file2: " $file2 cp $file1 ./first.pdf cp $file2 ./second.pdf pdftk ./second.pdf cat end-1 output second1.pdf rm second.pdf mv second1.pdf second.pdf pdftk first.pdf burst output %04d_A.pdf pdftk second.pdf burst output %04d_B.pdf rm first.pdf rm second.pdf pdftk *.pdf cat output out.pdf cp out.pdf $fileout cd .. rm -rf join done pdftk *join.pdf cat output complete.pdf
It all works pretty well for the most part. Some of the pages came out a little askew:
This maybe due to my poor cutting, not having set the feeder correctly, or the generally dog-eared nature of the book.
Diagrams came out pretty well:
Though, you can see some compression artifacts. It could also do with some post processing to increase the contrast perhaps. I might try the next book at 300dpi (I should also probably uses the black and white scanning mode).
At first I attempted to solve this using the sieve code I wrote for problem 3. However that code used Python lists and was removing elements as it progressed. That was horribly inefficient. So I’ve learnt to use Python arrays, which I was surprised to learn are not a native data structure in Python. Anyway, for my reference here is the code:
import math
from array import array
def getprimes(input):
myarray = array('L',range(input))
myarray[1] = 0
for n in myarray:
if n != 0:
for j in xrange(n+n,int(input),n):
myarray[j] = 0
retvals = []
for n in myarray:
if n != 0:
retvals.append(n)
return retvals
p = getprimes(2000000)
sum = 0
for i in p:
sum += i
print sum
I recently purchased a Silverstone GD05 case, this is a mATX case which is sold without a powersupply. It’s relatively pricey ( 80GBP ). Here are my notes on the case.
It’s pretty bulky for a desktop case by modern standards but there isn’t too much wasted space internally.
There are three large internal case fans, which given their size are surprisingly quiet. I found it a little odd that one of the case fans is directly behind the 5.25″ drive bay, pushing air into a flat sheet of metal. Another curious design decision is that the power supply fan inlet in under the case. All the fans are sucking air into the case the air gets blown out of the back and top of the case. One fan can be controlled by the motherboard, for the others an adapter is supplied:
However this means they run at full speed all the time. In my case the fan connected to the motherboard is running significantly slower. However I’m currently only using the on board video. With a decent modern GPU or 2 installed you might find the cooling gets pushed a little harder.
It was a bit of a struggle getting the ATX port faceplate in, and even when installed it bulges out in an unsatisfying manner:
Another curious thing is the PCI faceplate mounted directly above the PSU. I suppose this could be for installing external PCI or eSATA ports?
Overall it’s a reasonable case, there’s enough space for a powerful desktop without it being a full tower. The build quality is “ok” but I’d hoped for more for 80 quid. I hate the “silver effect” buttons of the front. I’d like to find a standard PC case with the build quality of a Mac at a reasonable price, but they don’t seem to exist…
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