I forgot to say that I also have the large TI printer that was used with this model of computer.
For history, my DS990 was used in one of the famous old french factories, that produced the "Dentelle de Calais", a prestigious lace. I also collected 8" disks and mini-tapes, they contain the programs a datas of the factory :-)
I own the same configuration ds990/1 fd1000 omni810 but I miss original operating system. I was able to run some floppy of 771 but it seems not completely compatible in floppy writing. It fail for example, the IBM exchange utility. Excuse me for my bad English, I'm Italian :-)