Joe,

I used three HP 2116's in the flight control lab at Boeing (Wichita, Kansas) in 1980 - 1982 for flight simulations. What beasts! Press Clear, Set the address for the IBL (Initial Binary Loader), press Run, go get a soda and then get after it. We used paper tape to load aero coefficients and weight properties to avoid (1) the timeconsuming task of re-compiling for a new flight condition and, (2) storing all that data in the small, precious memory.

Shortly thereafter we upgraded to an HP 21MX (it had a Writeable Control Store for "do it yourself brain surgery" on the instruction set) running RTE III and a removable platter (the head positioner was electric, not hydraulic). Anytime we wanted to add a new device like a CalComp Plotter or DACs for strip chart recordings we had to re-gen the OS to set addresses for the Device Control Blocks.

Then we got serious about doing real time, hardware in the loop simulations and moved to a to a SEL (System Engineering Labs) and finally an ELXSI, both running an RTP (Real Time Peripherals) cabinet which provided direct access to the backplane.

Bruce