[TSTIL] Plotter

[ This is a part of "The Software That I Love", a series of posts about Software that I created or had a small part in ]

1997 - Plotter

As my dad worked at HP he saw all kinds of equipment in the office. At some point he brought home a couple of broken inkjet printers. He took out a lot of parts, ordered a microcontroller from the US and created a simple plotter for A4 paper with the stepper motors. Back then microcontrollers were expensive and difficult to program, there was no Arduino IDE or anything like it. If you weren't careful you could blow out your parallel port.

Dad built all the hardware, connected the microcontroller, and hooked up a driver and a small library so we could control it from Delphi. My job was to program the code to move the head around and up and down. Up means the marker is not touching the paper, down means you're drawing. This was great, as you could program something and see the results in the real world right away! I still enjoy try to get instant feedback loops whenever I'm working on a system.

I started with creating the logic for the letters. If you draw an A, you had to create 3 lines, 2 diagonal and 1 horizontal. On and on for the letters B to Z. It was quite a lot of work but after some time I got good at it and start optimizing patterns. Dad showed me how to make procedures to re-use logic. I figured out how to abstract things so that letters could be drawn from a relative starting position, how to do line wrapping, etc. Lots of fun.




next1999 - Reverse engineering the binary format of HP ChemStation

previous1996 - JTJ Rekenen


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