UT70 was found as a source listing, on a "preliminary" paper copy
"P1" of the MPM-241 User Manual for the MS2000 
 RCA MicroDisk Development System.
https://groups.io/g/cosmacelf/files/UT70
contains the PDF UT70 source listing and the UT70 .bin file. 
This was discussed in cosmacelf during March 19 2020 and following days.
The discussion did not determine if the two MPM-241 documents
referred to different hardware or different versions of MS2000 "DOS".

UT70 vs UT71 eyeball source listing comparisons.
by Herb Johnson Mar 28 2020

LOOP is slightly different coding.
SCAN is slightly different coding.
UT71 includes code for disk support.
ERROR looks the same.
SUBST looks the same.
DEXIT looks the same.
TIMALC for UT71 includes a longer version string.
CKDEC for UT71 has added code for FND
TYPE has slightly different coding.
BEGIN has slightly different coding.
HEX3 is slightly different.
OPTION looks the same.
(routines forward look the same)
INSERT has different coding.
DISK I/O ROUTINES
UT71 uses reg F as "PARA"
UT71 includes SISCMD and INVCMD
UT71 includes MAXTRK and MAXSEC
UT71 includes BOOT code before LOAD
UT71 and UT70 have very different MICRODOS loading code
MICTST slightly different, LOADOK looks the same.
UT71 has "SPECIFY" before RECAL
RECAL looks the same.
CMD code is different.
WAIT code is different.
SEEK code is different.
disk read and write codes are different.
UT71 has keyboard input/output routines 
UT71 keyboard and disk routines integrated in some way.
TEST self-test code is very different.
The "DISK I/O ENTRY TABLEs" are different;
  UT71 has several earlier entry points.