Thanks for these suggestions. I'm sorry to respond with a stupid question, but here goes:
1. How can I set comspec to be c:\freedos\4dos.com instead of its default setting? I know that I could do this by mounting a disk image and running some other version of DOS than the built-in Freedos, but this whole project is built on the default Freedos setup, and I would like to retain it if possible. I've searched for "DOSBox config.sys" and similar searches, but haven't found an answer. (As far as I know, comspec can't be changed after the initial environment is loaded, so setting it in autoexec.bat or from the command prompt doesn't have any effect.)
2. Next, some other commands run successfully when I use "Run DOS Command" in WPDOS 6.2, but there seems to be a shortage of memory. For example, if I run EDIT, it crashes with an "Out of memory!" error. And if I run MEM, it reports 185KB free. If, however, instead of using "Run DOS Command" I use the "Go to DOS" function to shell to a command prompt, MEM reports 615KB free. I don't understand what's going on here.
With WPDOS 5.1, I can use "Run DOS Command" and run EDIT and 4DOS successfully. If I run MEM, I don't see any output, but presumably there's enough. If I use "Run DOS Command" and run 4DOS, and then run MEM, it reports 615KB free.
Any advice will be gratefully received.