Wordstar Version 4 for CPM is a Z3 shell but in some cases it does
not properly handle the shell stack. For most shells only the first
byte of the shell stack needs to be initialized at cold boot but this
is not true for WS4. If you are having problems with exit from WS4
while using ZCPR with shell capability, run SHELLINI.COM before using
WS4(or you may modify your BIOS to initialize all 128 bytes of your
shell stack). My STARTUP.COM alias includes SHELLINI.COM.