Originally Posted by
Linktrained
My very own ZX81 battery powered computer from 1982, recorded digitally on cassette tapes.
Actually, the recordings were analogue, and Sinclair machines used DA/AD conversion to translate between the two. This was why my Spectrum-owning friends all had tape recorders with a spot of Tipp-Ex on the volume and mic pots marking the "sweet spot" where that particular Speccy could make sense of what was on the tape.
In reference to what you're saying though, all the examples you give are of digital transmissions where the source and target spoke the same digital "language". Going back to your ZX81 example, you could not take the tape with your program on it and load that program into, say, a Spectrum - which shared the same processor but the ROM kernel and architecture was different - or a Vic-20, which had a different CPU as well as a very different architecture.
Checksums only work if the algorithms at each end are identical, and even then you still have the issue of how the data is processed at each end. It is the interpretation, processing and storage of the data between different architectures rather than the transmission that is the key problem here.
@jcj : Whoa there - the system used by the CEV on behalf of the BEA had common standards, *was* compatible and *was* certified. It seems the BEA wisely chose to avoid any further processing of the data beyond using the certified systems to provide a human-readable hard copy for the very reasons I've suggested. These days, the technologies used to process, store and render the data in different forms are several orders of magnitude more capable than they were back then.
Let me make this clear - the post extract of mine you just quoted does not relate to how the data was actually handled, it relates purely to the difficulty level, technically speaking, that would have been involved in attempting to transfer the data to another machine to reformat it, a process which is commonplace today. I was trying to explain why CONF iture's complaint about the GMT time formatting etc. was somewhat unreasonable given the technical state of the art at the time.
Here's a copy of the FAA regs pertaining to DFDRs :
14 CFR 121.344 - Digital flight data recorders for transport category airplanes. | LII / Legal Information Institute