This assumes John is running DOS 6.0 or higher.
I can't remember if Interlink was available on DOS 5.0.
This one here is DOS 5.0 and doesn't have INTR*
Interlink sounds pretty useful, but it came a bit late in the DOS evolution.
I'll probably combine the ideas from Today with the .BAS ideas from
http://www.ibiblio.org/pub/academic/computer-science/history/pdp-11/rsts/dec
us/sig88/088009/msbpct.bas
John A.