I hedged with "I wasn't aware", "pretty sure", "ordinarily", and ended with a question mark. I don't know how I could have been more guarded in expressing my recollection as non-authoritative. OK, maybe "pretty sure" was a bit on the strong side. sigh Sorry for that.
> I said that the hardware had cassette tape access.
I thought your point was that IBM cassette drives, unlike the tape systems I mentioned, "were used on contemporary machines that PKZIP ran on."
If your intended meaning was something other than "original IBM PCs running ROM BASIC OS so they could access an IBM Cassette tape was a supported platform by PKZIP", then I apologise for not being smart enough to make whatever leaps of logic were required to understand what your actual point was.