I didn't think I had any 8086 software tools on my PC but I was pleasantly surprised to find that I did.
For disassembly:
objdump -D -b binary -m i8086 SV25mon.BIN
Add the option --no-show-raw-insn to omit the hex bytes.
For assembly:
as86 SV25_assembly.txt
This will be handy for developing code for my other 8086-based boards.
as86 has a syntax that is significantly different from the online assemblers and disassemblers.
nasm is much more consistent, so I have moved to using that.
ndisasm generates code in the right syntax for nasm, so I took the disassembly and re-worked it.