So sew files only give deltas of movements, not absolute values so if my starting point or one byte is off, it messes up the whole image. With this, I decided to just plot the deltas, expecting on my card there to be a lot of back-and-forth movements.

First I tested on the known good file (downloaded from the internet):

Yep - I expected it to be a circle around the origin.


And my readout:
that makes no sense. Something is wrong. Which sucks because the file opens with:
"832 DATA EXP L V" which looks like it could be a header. Then a little further along, there's this in a sea of non-ascii characters:
which looks very much like a version string. So I was hoping it would be right.

After some trial and error, I stopped using the A-1 address pin (which is suppose to be the LSB) and got this
That looks good - because this card contains text, it makes since that there's only side to side and up and down motions. But converting to positions yield: