I know FPGA/ASIC are for a specific task and they are not microprocessors and an OS is needed mainly if multiple processes (tasks) need to be run concurrently.
Just wondering if an FPGA/ASIC can have an operating system. Is there any real time need which may require this?
Well, you can use without doubt an FPGA without software, in fact many are used to support booting more complex systems (power sequencing, for example). But you can also define some kind of embedded soft processor needing an OS.
On the other hand no CPU really requires an operating system, you could probably program a Cortex-A (for example) bare to the metal. The operating system/user software is only a useful distinction in responsabilities.
There are also ASIC which are single task but are however microcoded with some mask defined program to do their job (some USB bridge comes to mind).
In short anything can go
As for the real time issue: there's nothing more real time than a state machine on the FPGA fabric (except maybe a real ASIC), every kind software is slower (since it's by definition interpreted and run on a state machine in the FPGA fabric)
You can put a soft processor into the FPGA logic, and there are a lot of FPGA parts with integrated hard processors, these processors are running software, so can and in a lot of cases do run an OS.
The FPGA itself though is a bunch of logic, it's not 'running code' so the idea of an OS doesn't make sense.
FPGA is not running any software so it cannot have an OS.
FPGA is a programmable array of logic gates. The gate connections are programmable.
All the logic already runs concurrently.
ASIC by definition would require an OS to include a uC is “Application Specific”. I have been part of a team that designed one with a 6805 in the late ‘90’s with a proprietary RTOS.
FPGA’s are the “glue logic” and often very complex logic.
That means by the context of the leading question, it would be correct to say it would NEED a uC and some RTOS to validate your assumption in the question, but it presumes you have both an embedded uC and RTOS to reside in an ASIC and ASICs generally have neither. When in doubt, check your assumptions.
