DDI-1. It was a package including the disk interface (with AMSDOS in ROM and CP/M 2.2 partly in ROM) plus the drive itself. The FDD-1 was an optional second dri

DDI-1. It was a package including the disk interface (with AMSDOS in ROM and CP/M 2.2 partly in ROM) plus the drive itself. The FDD-1 was an optional second drive but you had to have the DDI-1 first.