I never used computer cards, although I did write an implementation of Knuth's MIX, and an assembler for it, but I wrote it in 2017 for running on PC DOS. Never

I never used computer cards, although I did write an implementation of Knuth's MIX, and an assembler for it, but I wrote it in 2017 for running on PC DOS. Nevertheless, I did include an option in the assembler to punch a zero in the first column of each card other than the first and last cards. You can then line up and use a hook to easily find the first and last card, and it is easy to see which is which; other than the first and last card, the others can be in arbitrary order and it will still work. (These are the cards of the compiled deck, which does not use the same format described in TAOCP, but it should still be compatible with all MIX computers which use the loading mechanism described in TAOCP; my own implementation uses a single card bootstrap rather than two card bootstrap.) (Note that all of this describes the compiled deck, and not the source deck. There is no source deck in this modern implementation.) (I have also tried to figure out how to make it work if all cards including the first and last card are shuffled (in order for this to work, it would require bootstrap code on every card, and it would probably need to know ahead of time how many cards there are), although I have been unable to do so; maybe it is not possible.)