Use Chrome or Edge. Snapshot upload needs the card switch Up (Pause); key remapping works any time.
Snapshot / music upload (.z80 / .sna / .ay / .pt3)
Accepts .z80 (v1/v2/v3), .sna (48K/128K) snapshots, and .ay / .pt3 (Vortex Tracker) chip-music. Upload with the card switch Up (Pause).
Input mapping
Click an input on the left, then click a key to assign it.
Save your input mapping + memory-probe address to a .json file on your computer, and load it back later.
CV Out 2 — memory probe
Outputs RAM[address] (0–255) as 0–5V on CV Out 2. Default 16384 = screen memory (flickers with the display). Try a game variable for a live CV.
Keyboard passthrough
off
While on, your keystrokes are sent as Spectrum keypresses. Letters, digits, Enter and Space map directly; use Shift for CAPS SHIFT and Alt for SYMBOL SHIFT. Shift+0 (or Backspace) = DELETE. (Click back on the page if focus is lost.)