well fasm does not have any directive to specify the processor type.
and honestly i don't even know my processor type.
so how do i make sure that a particular instruction is available or not?

a nice idea would be that fasm would set some data/flag in my executable file
based on the instructions i have used. it will set a minimum processor needed.
and also link in some code at the start up routine that will check that flag/data to
see if the cpu on which my program is about to be run is the minimum needed
to run my code. it will check the pre stored flag/data and check the cpu for compatibility.

May Santa fulfill my wish this Dec 25

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Something on this theme: Macros to choose target CPU

thanks MHajduk!
I think while using these macros i will have to specify the required cpu type.
which will be based on the latest instruction i use, right? but the problem is i think it is
too much trouble to remember the instruction and where it is supported. would not
it be nice if fasm would guess the minimum cpu needed. and would add a code to
check for it as well.

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You could use CPUID instruction for determinig CPU type (for Pentiums and higher, if I remember correctly) and simulation of this instruction for older processors CPUID (not really) 80286 | Tomasz's code.

wow! that's a bit too much!
similar to hand coding instructions instead of using fasm IMHO

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no, it wouldn't.
- extra unwanted code
- if you want, you can add it yourself
- what to do if check fails? system-dependent code needed
- not every instruction is meant to be executed on current CPU
etc...

That would kind of go against the idea of it being the flat assembler.

Just use ONLY8086.INC, and your code will run anywhere.

why my request violates the flat part
of the flatassembler? please explain.

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It doesn't violate "flat" part (IMO), but it violates idea of flat assembler (and idea of any assembler...)