Once upon a time, there were three RTOSes named VRTX, pSOS and VxWorks.
VRTX and pSOS were special because they were written in assembler language, for assembler language programmers, and for systems that contained nothing but assembler language. They were “real” RTOSes for “real men” who carried processor reference cards in their shirt pockets and could divide 0x53662 by 05314 in their head.
VxWorks, on the other hand, sat alone. It gazed off to what it guessed was the future. It said, “I C it.” And along with “C”, it also saw Unix. (But that was the first Unix, not the more common Linux we know today.) The Unix that VxWorks saw on the horizon was the process-model of BSD and SystemV.
Sitting all alone, Little VxWorks just knew that was the future even though VRTX and pSOS laughed at the notion. So little VxWorks clothed itself in a C language wrapper so programs written in C would want to be near it.
And little VxWorks said, “Come, look, see what I have to offer!”
And the C programs looked and saw “exit()” and “environment variables” and “printf()” and they shouted with glee!
“Here is a home for us. Here is someone who understands what we want.”
And so the C programs found a home with VxWorks. Nonetheless, VxWorks was genetically related to those other two RTOSes. It could not deny its roots. So it had “tasks” instead of “processes,” and at least in her early days, she would say, “We don’t do processes because the memory and system call overhead are just too awful with this old clunky hardware.”
Many years would pass as VxWorks grew from child to youth and then through her teen years. And during those same years, that “old clunky hardware” lost weight and became faster and faster.
Today, VxWorks shifts her look and demeanor to many different environments and architectures. Sometimes she will be seen wearing a blue collar work suit and tool belt. Other times she may be costumed in a flight suit and white silk scarf that she drapes over the cockpit’s edge to flutter in the slip stream. At other times, she may act in more of an executive role, overseeing and sometimes chastising other operating systems that come to her for a safe and secure environment.
Today, VxWorks is an adult with all the complexities and dimensions that have accrued to her over the decades. And even though her roots and genes come from both the RTOS and the Unix world, she is both, and she is neither.
VRTX has almost completely vanished. The pSOS and pSOS+ operating systems are rarely found in development, but some instances remain and generate a small stream of royalty payments to the owners. And even though VxWorks still has a loyal following, it too is shrinking. For many, the future is with embedded Linux. (It is less deterministic than the RTOSes, but it seems that the customers have decided that fast enough is good enough. (You should feel somewhat uneasy about that, but when you board the airplane, you won’t know which one(s) are in control. Fasten your seatbelt!)