diff --git a/docs/io.pdf b/docs/io.pdf
new file mode 100644
index 0000000000000000000000000000000000000000..0a68389294838afc44f0c4145e70dca6ead42a2f
Binary files /dev/null and b/docs/io.pdf differ
diff --git a/docs/ladder.pdf b/docs/ladder.pdf
new file mode 100644
index 0000000000000000000000000000000000000000..b2f5e170ed63c127c5219cd0626b3445ddaa999e
Binary files /dev/null and b/docs/ladder.pdf differ