"Roger" wrote in message
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The point I'm trying to make is for glass panels the code is kept as
compact as possible which means custom software that has to be
certified. These things are a long way from what sits on our desks.


Amen Roger,

The code bloat these days is absolutely phenomenal. Remember when you could
put a complete Unix system with all the accessories, bells, and whistles and
run thirty or forty users doing real work with only 16 megabytes of disk for
everything! And back it all up on a tape cartridge. :-)

I remember doing a simulator/training system for McD's that simulated four
combat missle launch platforms at the same time with all of their
instrumentation and readouts while moving them about independantly in the
simulation and letting them shoot missiles at each other. Each launch
platform could be any one of four choices and you made the change over by
merely unplugging the display panel and plugging in a different one. The
computer computed the positions of all the players and simulated all of the
instruments in real time. It even did the timing for response delays
throughout the system, which were different for each of the launch platform
choices.

I wrote the operating system and all of the control routines for this system
in Z80 assembler. It all ran memory resident on a Z80 8 bit processor with
64K bytes of memory and NO disk drive. If any of you remember, the Z80 did
NOT have fancy arithmetic instructions. All it had was add and subtract and
all of the range, bearing, square, square root, and arcsin and arccos
functions had to be done with a "shift and add" type algorithym. All of
this, along with system parameters and data for all of the various launch
platforms fit into the 64K byte memory with room to spare. And it ran in
real time with instrument update accuracy within a tenth of a second window.

Compared to that, a glass panel is simplicity itself and the old Z80 is
plenty of processor to do the job. I might point out, though, that NO
multitasking operating system really qualifies as a "real time" operating
system. Nothing Microsoft has ever put out qualifies for "real time."
Also, they, more than anyone, have made millions from "code bloat."

I used to run the EMACS editor in a 32K Z80 machine. For several users and
with all of the documents they were working in the various windows ( up to
ten windows each ) all in that little Z80 machine.

The machine code for Notepad wouldn't even fit in that machine!

Program it from scratch for reliability and remember, every line of code has
to be certified!

Highflyer
Highflight Aviation Services
Pinckneyville Airport ( PJY )