While checking various 8 inch floppy disks we found these two disks that contain ISIS-II related files. The original disks are 77 tracks, 26 sector 128 bytes/sector, Single Density disks.
Since the ISIS-II format has been revered engineered by Perry C. Hutchison in 1977, we followed the guide and managed to extract the files from the disks.
Further study of the contents reveal that the second disk contain files that mention TANDBERG TDV2100 ASSEMBLER, TDV 2100 LINKER V.1.2, TANDBERG LINE EDITOR VER. 1.1 and TOS21 VER. 1.81. This probably means that this disk has been used for a TDV21xx system (TDV 2114 perhaps). But then there has to be some basic similarities between ISIS-II and TOS since the disk format structure is identical.
The first disk has a Copyright notice (C) 1975,1976 INTEL CORP so it is a probably a original ISIS disk.
This is the contents: