jinjin,
This was QDLU (not EDLU) ROA 219 4257/1 card - BIG size, not PCI, inserted to PC.
In fact it was SCSI interface, connected to IOU ROF 131 828/2 (IOU -InputOutputUnit).
There was also QDLU program, DOS based.
The program emulated external tape recorder (like Tandberg).
With the commands FAVOI, FATAE, FASTI etc you could prepare backup and execute it with DUUDI.
Finally you had MD backup on the PC and it was VERY easy to make reserve backups copies. Just copy last file to different folders.
No f-ing MINIX, MDDT, no pain in the a-s.
QDLU was working really very good and was very reliable .
QDLU was phased out in BC6, when IPU+HDU2 were introduced.
Any more questions, just ask
Regards