There are three emulators with different built-in (virtual) hardware available, as well as a tool to edit virtual SD cards that use the CFS filesystem.
When loading this from GitHub Pages, ROM and one SD card filesystem are loaded automatically. When loaded from local disk, you have to load the ROM and SD card manually.
The provided SD card image contains source code of all the included tools and of the kernel (ROM).
In addition to the original ed, memt and zasm binaries, my images also include a convenience zmake binary - zmake foo will assemble foo/glue.asm to foo and will overwrite existing binaries. There is also a BASIC interpreter based on TinyBasic, with lowercase variable/keyword support and added IN/OUT/PEEK/POKE/SYS commands.
Load SD card images using CFS filesystem; add/download/rename/reorder/remove files inside; compact/optimize filesystem; save as uncompressed or compressed (.PNG) file.