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Miloslav Ciz 2023-12-21 12:04:09 +01:00
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assembly.md
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@ -4,7 +4,7 @@ Assembly (also ASM) is, for any given hardware computing platform ([ISA](isa.md)
**Assembly is NOT a single language**, it differs for every architecture, i.e. every model of CPU has potentially different architecture, understands a different machine code and hence has a different assembly (though there are some standardized families of assembly like x86 that work on wide range of CPUs); therefore **assembly is not [portable](portability.md)** (i.e. the program won't generally work on a different type of CPU or under a different [OS](os.md))! And even the same kind of assembly language may have several different [syntax](syntax.md) formats which may differ in comment style, order of writing arguments and even instruction abbreviations (e.g. x86 can be written in [Intel](intel.md) and [AT&T](at_and_t.md) syntax). For the reason of non-portability (and also for the fact that "assembly is hard") you shouldn't write your programs directly in assembly but rather in a bit higher level language such as [C](c.md) (which can be compiled to any CPU's assembly). However you should know at least the very basics of programming in assembly as a good programmer will come in contact with it sometimes, for example during hardcore [optimization](optimization.md) (many languages offer an option to embed inline assembly in specific places), debugging, reverse engineering, when writing a C compiler for a completely new platform or even when designing one's own new platform. **You should write at least one program in assembly** -- it gives you a great insight into how a computer actually works and you'll get a better idea of how your high level programs translate to machine code (which may help you write better [optimized](optimization.md) code) and WHY your high level language looks the way it does.
**OK, but why doesn't anyone make a portable assembly?** Well, people do, they just usually call it a [bytecode](bytecode.md) -- take a look at that. [C](c.md) is portable and low level, so it is often called a "portable assembly", though it still IS significantly higher in abstraction and won't usually give you the real assembly vibes.
**OK, but why doesn't anyone make a portable assembly?** Well, people do, they just usually call it a [bytecode](bytecode.md) -- take a look at that. [C](c.md) is portable and low level, so it is often called a "portable assembly", though it still IS significantly higher in abstraction and won't usually give you the real assembly vibes. [Forth](forth.md) may also be seen as close to such concept.
The most common assembly languages you'll encounter nowadays are **[x86](x86.md)** (used by most desktop [CPUs](cpu.md)) and **[ARM](arm.md)** (used by most mobile CPUs) -- both are used by [proprietary](proprietary.md) hardware and though an assembly language itself cannot (as of yet) be [copyrighted](copyright.md), the associated architectures may be "protected" (restricted) e.g. by [patents](patent.md) (see also [IP cores](ip_core.md)). **[RISC-V](risc_v.md)** on the other hand is an "[open](open.md)" alternative, though not yet so wide spread. Other assembly languages include e.g. [AVR](avr.md) (8bit CPUs used e.g. by some [Arduinos](arduino.md)) and [PowerPC](ppc.md).