Jet Set Willy

Characters and sprites

The room uses character cells. Willy and the guardians are sprites drawn over them. Toggle the sprites to separate the two layers in this captured frame.

The room terrain

Each room packs four terrain cells into one byte. Change the room to see its base terrain and the glyphs used to draw it.

The map decoder at $2EE5 produced matching screen codes and colors for every cell in all 60 rooms. This view shows the packed terrain before conveyors, ramps, objects and sprites are added. The room's glyphs come from offsets $A0–$CF in its record.

The rope graphics

The swinging rope selects a triplet of sprite images for each position. Move the slider to inspect the three images before their screen coordinates and vertical expansion are applied.

The pointer table at $1856 selects 192 bytes per position. The staging loop at $16DE copied matching bytes for all 34 positions. Each segment stores 21 rows of three bytes, followed by an alignment byte.

Features

Explore connected rooms, jump between platforms, collect objects, and avoid guardians, arrows and ropes. The documented goal is to return to bed after collecting the required objects.

Reference screen

Analysis in progress

The Source tab carries imported Ghidra annotations on a booted snapshot. The room transfers, packed terrain and rope graphics have passed native checks. The remaining mechanics and retained loader data still need verification. See About for provenance and open work.

RESTORE and reset

In this disk image, RESTORE can restart the title. A CPU reset reaches the same restart stub with its memory-bank control pins configured as inputs. The stub changes their output value but leaves them as inputs, then jumps into BASIC ROM.