Re: SCADA systems running windows
80 yer old scada code is barely a few kilobytes, often hand cratfed assembly for the HAL with some high level language frontend typically compiled using Fortran or Pascal or running interpreted languages like Forth.
The young whippersnappers can't even write a bootloader that is below 100Kbyte ... These control systems have 8 k rom and 1 or 2k of ram and happily work.
in the early 90's i was working on an Ion implanter that was driven from a graphical touch screen running on an IBM 286 PC ( a real IBM , not a clone ) using iRMX as its operating system.
Every control on the screen was its own little executable sending messages to a custom piece of hardware. if the PC developed a problem , for example a control crashing the supervisor program would simply restart an instance of that control , bind it to the target and the machine would keep working. the control would request the last known state and reflect that on screen.
That thing was virtually crash-proof. I remember getting a phone call from the operator that there was an error message that popped up. The message said it had found a couple of parity errors in ram adress so and so and had marked the memory as 'bad'. The iRMX executive had reloaded new instances of the controls to a different memory offset, relinked them to their target and the machine happily trudged along. months later, during a scheduled service we shut down the pc, popped the hood, removed the 41256 type DRAM chip from its socket ( the address gave us an idea which one it would be) stuck in a new one, booted into system diagnostic, ran the memory test to verify the parity errors were gone and off we went. I know for a fact that machine was still operating in 2012 .... same computer, same software. It booted from a 10 megabyte MFM harddisk made by Nec and had 2 megabyte of ram.