Yeah, I ended up using something similar to your non-pi script to actually do the processing yesterday. (And today, I was able to follow shmem's suggestions to get the -pi working)

My searches indicate that debug.exe hasn't shipped with Win7^(1,2) (or probably beyond), though it did ship with Windows XP⁽³⁾. Regardless of normal, my Win7 64bit installation doesn't include it. I just used xxd, because it was faster than rolling my own hex dumper in perl -- though I should have, once I was trying to bring fellow Monks to help me. :-)

I was just using null-separated text for easy-to-create dummy data. Really, it is a binary data format, which can have the bytes 0x0A and 0x0D anywhere (not really functioning as newlines), but occasionally has embedded strings; I was trying to edit some of those occasional strings (and I couldn't get my GnuWin32 sed.exe to do the changes I wanted -- I was probably not escaping something correctly on the command line -- so I switched to perl, because I thought it would be easier (and I wanted to learn more about the -pi options, since I'd never used that combination, I'd normally just rolled my own file loop, like I ended up doing.)

Again, everyone, thanks for your help and suggestions. I've learned more, which is always my goal here.

¹ http://superuser.com/questions/510671 /is-there-debug-exe-equivalent-for-windows7: implies it doesn't ship with Win7
² http://www.computerhope.com/forum/index.php?topic=129058.0: implies it doesn't ship with Win7
³ https://technet.microsoft.com/en-us/library/bb491040.aspx: did ship with XP