Well, CoffmanStarter, in fact the A310 system architecture is much as you describe - it receives ('pulls') information from the aircraft systems which is processed by an on-board PC (with another on 'hot standby' for redundancy) rather than by a Toughbook (although that was considered instead of 1 PC, but later rejected). The input device is a keyboard with track ball, the display is on a screen which can also be switched to the receiver surveillance system, should that system's identical display screen fail. The only potential single point of failure would be the keyboard, but a spare is always carried....
On-board software is the same as off-board, so a mission is normally planned off-board on any normal laptop with the application software, then transferred by USB pen drive to the on-board system - which cannot corrupt any aircraft system as it is read-only. Although there is an output to a flight deck printer as the pilots don't have their own display, so need to review any mission changes in printed form.
The application software is modular by design, in addition to the core application programme, it includes various databases including those for the 'host platform' aircraft performance and for certain receiver types' AAR performance - plus magvar, navigation and world-wide stat met, as well as about 160 different AARA locations in US and Europe. So tailoring the system for use in other aircraft would, in engineering terms, be quite simple.
And it works very well indeed!
One tweak which has recently been added is a system to calculate alternate fuel requirements, using a simple 'y=mx+c' experienced-based empirical rule for up to 100nm alternates, then FCOM values for greater distances. But rather than being restricted to optimistic 'best level' calculations and default final reserve values, the user can (if required) specify landing fuel requirement, holding fuel requirement, approach fuel required at the alternate, transit levels and (if >200 nm) met corrections to better suit his needs. Something which would be quite useful for airline use as it performs the whole FCOM calculation process in rather less than the bat of an eyelid! So if you were facing a chaotic mass diversion due to Spanish ATC ineptitude in mid-summer, you could specify a diversion at, say, FL100 rather than using the FL310 figure - and perhaps a higher final reserve......and let the box do the sums!
Last edited by BEagle; 29th Aug 2014 at 09:58.