Friday, March 3, 2017

A few more printer tests

I hate leaving questions dangling, so I ran just a few more tests.

As you can see in this photo, the Epson M-32TL printer has three print wheels. The right-most wheel has 12 symbols and two blank spaces on it. The two other wheels are identical, with 10 numbers and 4 symbols, but one carries blue ink and the other red ink. They're really rubbery bands rather than wheels, and the solenoid causes a hammer to press one of the bands forward onto the paper, but I'm going to call them wheels.

The top two lines of print are the basic tests I ran yesterday. Before printing the third line I changed the program to print a red shift symbol (index 13) instead of a space symbol (index 10) in the third column. As expected, this causes the printer to use the red numeric wheel instead of the black numeric wheel. This I'd learned from observing the behavior of the printer as part of the Canon P170-DH calculator.

Will this printer print fewer than three symbol columns?

Before printing the fourth line I removed the "×" (multiply) symbol from the print sequence. Although printing the red shift symbol printed in column two still results in using the red numeric wheel, column three is still printed using the symbol wheel (the "%" and "•" characters are both index 12). So, no, it will not print fewer than three symbol columns.

Will this printer print more than three symbol characters?

Before printing the fifth line I restored the "×" symbol and added a "◊" (diamond) symbol after it, before the red shift symbol. The printer printed all three symbols, but instead of performing a red shift it printed a "#" (hash). This isn't unexpected, as the red shift and "#" are both index 13 on the wheels. So, no, it will not print more than three symbol columns.

Lessons learned this morning:
  1. The M-32TL printer always prints three columns with the symbol wheel before printing the rest with one of the two numeric wheels.
  2. Printing the red shift in a numeric column prints the equivalent numeric wheel character.
  3. Printing the red shift in column 1 does not cause a red shift but otherwise gives the expected results (I ran this test after taking the pic).
  4. From lessons 2 and 3 we learn the red shift character must be printed in column 2 or 3 to take effect.
Not bad for an hour's work at the break of dawn (too much caffeine yesterday!).

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