i sincerely wish more programmers of the web app / web server / commodity unix-y server ilk (aka my people) were good-faith curious about Cobol and mainframes instead of gawking or snarking or dismissive, especially considering how many mission-critical services flow through them

first, much of what we take for granted (8-bit bytes, byte-addressable RAM, virtualization) originates in mainframes. the 1st program we'd call a compiler was for Cobol. but then a separate evolutionary branch as unix & c appears and later the web define "server" for a generation

we were ingrained in the 90s and 00s that "scaling" meant "horizontal" -- just add more nodes and spread out the demand between them. but what if scaling, but vertical? it solves (by simply avoiding) a lot of consistency problems big orgs are still fighting today with algos.

the hardware engineering! redundant PSUs, auto-retry of faults/failed txns, accelerated I/O (by co-locating processors with NICs) for more throughput and concurrency. mf are built for high-availability and lots of transactions.

you often read about 40-year-old systems, but this actually tells a better story about upgrades than we have on the web. new hardware comes in regularly and existing software just works. compare this to say npm where you can barely produce a running app from a few versions back.

a key thing i wish people understood is orgs make rational economic decisions to obtain or keep mf running! they are not dopes or ignorant of alternatives. "the cloud" is not an obvious win, a lot of orgs have figured out on a per-transaction basis, it can be a lot more expensive

anyway like many things, it's more complicated, richer, and maybe more sensible than appears at first blush. i myself have little experience myself beyond the hercules VM, a few Cobol apps, and writing a tool to convert EBCDIC data in copybook-serialized files. neither pro or con

but it's a rich vein of computing that is worth your time exploring if you are interested. definitely follow @bigendiansmalls and @mainframed767 for some truth, and start poking around. ultimately it's a von neumann machine, so you already know how it works ;)