There were hardware ISA boards that purported to provide boot-sector protection e.g. ThunderByte Antivirus which I found from a Google search: https://en.wikipedia.org/wiki/ThunderByte_Antivirus
There were hardware ISA boards that purported to provide boot-sector protection e.g. ThunderByte Antivirus which I found from a Google search: https://en.wikipedia.org/wiki/ThunderByte_Antivirus