DOS lives

Yesterday, I visited a company that designs and manuactures electromechanical relays. The engineering lab was filled with automated systems used to characterize relays for parameters such as make voltage, break voltage, on resistance, etc. All of the systems run DOS and have been in service over 20 years. The systems consist of home-brew electronics with custom boards, all using through-hole analog and digital ICs. The digital IC are all TTL logic in through-hole packages. A custom ISA card with TLL logic is the interface to the test box.

Engineers at the company have changed PC motherboards from time to time. They are evaluating a mother board to replace an aging motherboard with a 500-MHz processor. Because each new generation of motherboard runs faster then the previous one, engineers have to tweak the timing in the software to slow the system down. Finding a motherboard with an ISA slot isn’t so easy anymore.

These systems run without a mouse, using only a keyboard as the user input device. The systems can produce graphs of measurements such as on resistance. They’re even networked so they get the latest test limits from a central database and they do it all in just 640 kbytes of RAM. Engineers have written the code in C and assembly lanaguage to make it fit.

Sometimes, you just don’t need the latest operating system.

Are you using DOS? If so, tell us about your application.