Mmtool 326zip -

Understanding MMTool 326.zip: The Essential Utility for Legacy BIOS Modding

However, for modern hardware (Intel 8th gen+, AMD Ryzen 3000+), you should avoid mmtool 326zip. Its 32-bit architecture, lack of capsule support, and inability to handle signed firmware volumes make it obsolete. Instead, graduate to UEFITool or the official AMI MMTool 5.x. mmtool 326zip

Loading the ROM: Use the "Load ROM" button to select your AMI BIOS file (usually .bin or .rom). Understanding MMTool 326

If you are following a specific guide for a motherboard mod: What is the motherboard model? for modern hardware (Intel 8th gen+