Apologies, I did the American thing. Checks, which get turned into X9.100 files, which are just digital versions of bags of bundles of checks, with check images that were TIFF images in CCITT T.6 encoding.

I don’t know if you’re being serious, but I can confirm from my time at as a developer at a banking software company, we didn’t use a hard RT OS even for like Mosler or Hitachi high speed check sorters. Just fast C++ code. (On Windows XP still, when I left in 2016)

(Work load is basically: batch of checks is loaded into an input hopper, along with check sized pieces of paper which are headers and footers, machine rapidly scans MICR lines and they go flying towards output pockets, and our code has something like 20 ms to receive the MICR data and pass back a sorting decision.)

I don’t know what people call this, but I’m curious if you also need future balance prediction, basically “here’s how much left over you’re going to have this payday, next payday, etc”. I might switch from my homegrown spreadsheet to one of these recommendations if they also support that.

(I’m talking about something where you input your known scheduled debits and credits, especially for people with biweekly paychecks but monthly debits, and then you match recent actual activity with what’s expected. So you get “current balance is $1800 but it’ll get as low as $300 before you get paid next” type info to keep you from over spending.)