As you should have guessed, this patch translates the game from Japanese to English.

From the readme file:

This patch fixes a design flaw where leaving through the western exit of an area located in the bottom-left corner of the overworld map may take the hero inside a red block normally impassable. (For those somewhat familiar with my "Overworld Map" webpage, the area in question is located at C11.) What this patch does is replace the aforementioned block with the adjacent plains tile.

From the readme file:

This patch fixes a design flaw where the hero, upon reaching the end of the "Cave Level 6" map, will walk through the tiles that constitute the ceiling as if he were levitating; this is possible by slipping into a tiny gap in the ceiling while in midair. The bug is resolved by filling the aforementioned gap with a single red block, which effectually prevents such a situation from occurring.

From the readme file:

This patch fixes a design flaw where reaching the end of a cave that scrolls vertically will, under appropriate conditions, allow the hero to walk through blocks normally impassable. Specifically, the bug exists in all vertical-type caves except the "Another Cave" map. This fix arranges the tiles of the caves in a manner such that it will no longer be possible for the hero to walk through impassable blocks in such a situation.

Normally, when you get a "Game Over" message in a boss battle, it will appear as if there is no textbox displaying the message. This is due to the fact that the space character, which constitutes the textbox, usually refers to a black tile; during boss battles, however, it refers to the floor tile. This patch fixes the oversight by using a black tile from the menu on the right side of the screen, so that the space character is no longer utilized. This also fixes a minor graphic bug where the floor tile that fills in the space between "Game" and "Over" may cover a section of the monster's sprite.

To determine whether the hero should die when he sustains damage, the algorithm checks to see if his POWER value is negative. This creates a situation where the hero can survive with a POWER value of zero; the patch fixes this loophole.

When the hero uses medicinal herbs in order to escape death, his POWER becomes equal to twenty-five percent of the maximum value. In such a situation, because of an oversight, the hero cannot avoid incurring damage again, as he is never cloaked with temporary invulnerability. This fix makes the necessary adjustments to the code.

This one fixes the bug where the arrow characters on the Password Screen will become yellow instead of beige after they have been highlighted.

From the readme file:

To determine whether the yellow shield should remain available for sale, the algorithm evaluates a variable by looking up its value, which indicates which shields the hero has in his possession: none, blue, or yellow and blue. Because it is impossible for the expected value—which was defined to exclude the blue shield—to match the actual value, the yellow shield will always remain available for sale; the patch rectifies that mistake.

On the overworld map, as well as maps in which a boss can be fought, the game keeps track of the last direction key the player pressed; this is used to set the direction of the sword object to the current direction of the hero. One problem that arises is that when the hero arrives at a room that houses a boss, the variable that determines the angular direction of the sword is not modified to reflect the fact that the hero is oriented to face south; the patch fixes this issue.

Normally, when the condition for a cave to be revealed is to break the rock that conceals the entrance, the algorithm checks to see if there is a plains tile at the same location, which serves to prove that the rock has been broken; once the aforementioned tile is detected, it becomes possible to enter the cave. However, the code for the cave at G12 lacks such a check. As a result, the entrance to the cave will be revealed as if there were no conditions to be satisfied; the patch restores the correct behavior.