The DWC90 that I used to work on had a Floppy drive instead of a tape. There were switches on the control cards that had to be set and cycled in a sequence to load the software. Also there was at least three disks plus e-packs. Also had to set it to display English instead of Japenese and inches instead of metric. Do you have any documentation for the machine? If so check chapter 5, system loading for the step-by-step procedure. They were known to corrupt the software and require reloading after several months.