This cartridge is based on the Raspberry Pi Pico (aka Purple Pico in this build) multi-ROM cartridge and file launcher for Atari 8-bit computers. It uses the open source firmware developed by Robin Edwards.I built them for use on these vintage computer systems.It has 16 MBytes of onboard flash memory for ROM storage, enough for about 900 files or so, and runs at a clock speed of 125MHz. It can handle file sizes of 128K or less, which covers about 99% of all the game ROMs.Your files are loaded onto the A8 PicoCart by connecting it to the USB port of your computer and dragging and dropping them into the carts flash memory. You can create folder structures, and each folder can hold a max of 256 files. The first 30 characters of the file names will be displayed in the Atari onscreen menu.It handles the following file types flawlessly:-CAR ( Cartridge files with standard 16 byte header)-ROM ( Raw Cartridge files without any header-XEX (files made of one or more blocks of memory datafile formats)-It also has limited support for ATR files (multi-file programs typically streamed from an actual drive connected to the SIO port on the computer).-It, like most other cartridges, does not directly support BAS (tokenized BASIC) or CAS (binary images of cassette tapes) formats, however there are utilities available to convert these formats to one the A8 PicoCart will work with.Perfect for the XE and XL series computers, works also with the 400 and 800 although due to the smaller memory size and hardware limitations on these machines, larger ROMs may not all work. You may have to depress the "Option" button while loading larger games intended primarily for the XE and XL series to prevent BASIC from loading which frees up more memory for the game itself.I built these cartridges and tested them on an Atari XEGS to verify they work with a sample of all the supported file formats.Asking $37.00 for the cartridge plus $8.00 shipping in the lower 48 states if required.