I unearthed some old TU58 tapes that luckily was readable (after carefully
replacing the tension band)
It resulted in two RT11 V4 images with two versions of the formatter
program. One is bootable and the other not.
http://storage.datormuseum.se/u/96935524/Datormusuem/Dilog/DQ604/sq604c.dsk
http://storage.datormuseum.se/u/96935524/Datormusuem/Dilog/DQ604/sq604d.dsk
I tried to run the formatter program in Simh:
.run sq604C.sav
TEST AND FORMAT DQ604 DISK SYSTEM (REV C.)
DRIVE FORMATS AS RL01 UNIT (5.24 MB)
SWITCH 3 CLOSED ENABLES BOOTSTRAP
THERE ARE 17 PHYSICAL SECTORS PER TRACK
(2) ALTERNATE CYLINDERS MAY BE ASSIGNED PER UNIT
THE INTERLACE FACTORS ARE TWO OR THREE TO ONE
DATA BUFFER ERROR
USE PROCEED (P) TO REPEAT TEST
HALT instruction, PC: 006312 (BR 6202)
.RUN SQ604D
TEST AND FORMAT DQ604 DISK SYSTEM (REV C.)
DRIVE FORMATS AS RL02 UNIT (10.48 MB)
SWITCH 3 CLOSED ENABLES BOOTSTRAP
THERE ARE 17 PHYSICAL SECTORS PER TRACK
(4) ALTERNATE CYLINDERS MAY BE ASSIGNED PER UNIT
THE INTERLACE FACTORS ARE TWO OR THREE TO ONE
DATA BUFFER ERROR
USE PROCEED (P) TO REPEAT TEST
HALT instruction, PC: 006312 (BR 6202)
So it appears to be runnable.
I also found the manual for the board and scanned it:
http://storage.datormuseum.se/u/96935524/Datormusuem/Dilog/DQ604/DQ604.pdf
Now the next step is to see if this can make the DQ604 board I have working
with David Gessweins MFM emulator.