(As others have said, it's probably better to choose the doi.org URL over the dl.acm.org one in general. Three cheers for HOPL!)

The HOPL (1) book (ISBN 9780127450407 ) is at https://doi.org/10.1145/800025 (direct link to ACM: https://dl.acm.org/doi/book/10.1145/800025 ) .

There’s just a lot more space when you can move in three dimensions, so I don’t think the congestion limitations of non-flying cars are likely to be replicated. IIUC (I’m no expert) that’s one of the most attractive features of flying VTOL vehicles.

You're bandwidth-limited on a sparse serialized landing site map no matter what, and you need far higher distance margins that will eat up basically all of the dimensional advantages.

If ground vehicles side-swipe, it's just an insurance claim. If flying vehicles sideswipe, it's a Problem(tm).

I honestly think the most attractive features of VTOL vehicles are that they are from sci fi, and you can look up and see a bunch of empty space and wish you were there while sitting in traffic.

For good measure you might as well see what the young Knuth looked like, too: https://www.youtube.com/watch?v=dhh8Ao4yweQ .

Good move. They look quite different.

The Stanford linkrot bandits have struck again I’m afraid.

For what it's worth (and though I do have some complaints about stanfordonline), the URL https://online.stanford.edu/donald-e-knuth-lectures works fine for me.

The YouTube channel seems to have them: https://www.youtube.com/playlist?list=PL94E35692EB9D36F3

Thanks for that. They seem to have been embarrassed into putting the stanford.edu page back up for another few months. I think my first encounter with Stanford's website archival policies was when I found that they'd shot an old, once-much-hyped interview with Alvy Ray Smith into the void: https://news.ycombinator.com/item?id=28064844 . Anything on the Stanford website which purports to be education or history is a marketing op wearing a smiling mask. That in itself would be largely fine, but when the marketing objectives have been met they'll delete everything with what seems to be a contemptuous glee, refusing to even use the Wayback Machine. Doesn't say much for that institution.

The UK's National Musuem of Computing has a nice demonstration video https://www.youtube.com/watch?v=xGEAPVCuwvY . Apparently delay-line memory also went on to have wide use in colour TVs before the arrival of cheap semiconductor memory https://www.youtube.com/watch?v=EPQq7xd3WdA , which was quite appropriate as it had come from radar in the first place https://www.youtube.com/watch?v=JZLpbhsE72I&t=675s .

38:37 https://www.youtube.com/watch?v=JZLpbhsE72I&t=2317s in Jay Forrester's "The Design Environment and Innovations of Project Whirlwind" talk ( https://www.computerhistory.org/collections/catalog/10270308... ):

> There was a desperate search for better memory. We seriously considered. at one stage. renting a television microwave link from Boston to Buffalo and back so that one could store something like 3,000 bits in the 3 milliseconds of round-trip transit time.

Though I'm not sure why they wouldn't have just used a delay line for that task: that form of memory was already in use in computers, as discussed by Forrester himself from 11:15 https://www.youtube.com/watch?v=JZLpbhsE72I&t=675s .

The Digital Library contains a lot of older material which predates the Web and has often never been put online anywhere else: old Joint Computer Conference papers and so on.

And they spent years resisting pressure for open access before that: this has been in the air for a long time.

Uncharacteristic of the IEEE to fail in its core mission like this by missing an opportunity to take money from someone ...