This is documentation for a web-based TRS-80 emulator. It is used in various websites, including My TRS-80, the cassette decoder, and the IDE.
Hover the mouse pointer over the emulator to show a menu in the upper-left. The items in the menu depend on the specific site embedding the emulator, but can include resetting the machine, showing a configuration panel, taking a screenshot, toggling audio, rewinding the cassette, and editing the in-memory Basic program.
There are two configuration panels. The one shown by clicking the gear icon lets you select the computer model, Basic level, character set, and amount of memory. The one shown by clicking the eye icon lets you select the phosphor color, background color, and whether simulated scanlines are shown.
When emulating a Model III, use the Esc key to press Break, the \ (backslash) key to press Clear, and Shift-Hyphen (underscore) to toggle uppercase/lowercase (what was Shift-0 on the real machine).