Mattel Test Cartridges Mattel's test cartridges were used by Mattel and others to diagnose malfunctioning Intellivision consoles. This is an attempt to document the various Mattel Test Cartridges out there. This information is likely incomplete. As folks contribute more info, this original post will be updated. Note that freewheel's "FW Diagnostics" cartridge is not listed here but is a modern homebrew test cartridge. Known Cartridges There are 7 known Mattel test cartridges. The