Ages ago when we were building networks using super-expensive 64kbps WAN links, a customer sent us a weird bug report:
Everything works fine, but we cannot transfer one particular file between two locations – the file transfer stalls and eventually times out. At the same time, we’re seeing increased number of CRC errors on the WAN link.
My chat with the engineer handling the ticket went along these lines:
Long long time ago, we built a multi-protocol WAN network for a large organization. Everything worked great, until we got the weirdest bug report I’ve seen thus far:
When trying to transfer a particular file with DECnet to the central location, the WAN link drops. That does not happen with any other file, or when transferring the same file with TCP/IP. The only way to recover is to power cycle the modem.
Try to figure out what was going on before reading any further ;)
Decades ago I got involved in another interesting project: let’s build our own file server operating system on top of Z80 CPU. Yes, I was at university (how did you guess?) and No, it never really took off.
After I completed the LAN-over-RS-232 project, it was obvious (well, not in retrospect) that the solution to every problem must be Z80 computers connected with some crazy RS-232 wiring. A few years later we had to write an application to support rally races. Guess what the solution was ;)
It was early 1980s and I was just entering my MacGyver phase when someone asked me “could you make a local area network out of RS-232-based shared bus?” Sure, why not, it can’t be that hard…