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README.md

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+# Python-based fx-92 Scientifique Collège+ interpreter
+
+This is an alternate imlementation of the fx-92 SC+ Algorithmic application. It
+interprets programs read from QR code URLs or text files, and renders images
+using the SDL.
+
+Requirements:
+* Python ≥ 3.5 (may work with older versions)
+* PySDL2 (`pip3 install --user PySDL2`)
+
+## Running programs
+
+To run programs, execute `fx92.py` and specify an input file:
+
+```
+./fx92.py [-s|-u] <input file> [options...]
+```
+
+* If the input file contains text instructions (for example `goto 12,35`),
+  specify `-s` (this is the default).
+* If the input file contains a QR code URL (for example
+  `https://...F908313200333500`), specify `-u`.
+
+The input can also be set to `-`, in which case the interpreter reads from
+standard input. Typical use case is for URLs:
+
+```
+echo -n "F908313200333500" | ./fx92.py -u -
+```
+
+## Output options
+
+* `--scale <n>` lets you set the (integer) scaling ratio of the output.
+* `--save <bmp>` will save a screenshot of the output to the designated file.
+* `--quiet` will "hide" the window while executing. _(At the moment the window
+  is still shown, but closed immediately, due to SDL subtleties.)_
+
+## Tests
+
+A few units tests are provided. Run `tests.py` to execute them.