Long story short, practice tests are boring, and boring times provoke doing boring tasks, such as learning howto decode barcodes.
The coputer read sheet contains a 4 by 8 square matrix, with certain squares blackened.
Hmm, 8 squares, sounds like 8bit binary. Kinda. This is what I learnt, remembering that I was in an exam so I couldn’t use outside world help.
This is the barcode if it was written as binary (the first few attempts of me decoding it failed because I was reading it upside down).
11011100 | A
00001101 | B
00010101 | C
00000001 | D
(3349)
Now to read is quite simple, you get rows B and C and put next to each other, which make a 16 bit binary code.
0000110100010101
Which equals 3349, correct according to the number under the barcode. Now the next problem is what are rows A and D for. I presume they are for check sum, row D is a simple, “this row should equal one” check, but row A is left. If anyknows how the checksum works, comments would be nice. Btw, this was from a QCS prac. exam, I thought they would use something a little more harder.
Some more barcodes
00010111
11110001
11110110
00000001
(61942)
01111110
10000010
11111110
00000001
(33534)