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    <blockquote> <p>... So that for your CPU you could only use this type of assembly to talk to your hardware.</p> </blockquote> <p>All languages eventually convert to instructions that are executed on real hardware, whether that is done fairly directly as with an assembler or through a high level of abstraction as with C. The tricky bit is actually getting the machine instructions to manipulate the hardware in ways that you want since one point of higher level languages is to shield you from the hardware details.</p> <p>Some languages, like C, are designed with the intent to manipulate hardware directly and so they include keywords like volatile to prevent the compiler from otherwise optimizing away references to device registers. These may be written and not read back so that the compiler thinks the value saved is never used again. Or it may be necessary to read a device register though the value is never used. There are also miscellaneous instructions for such operations as enabling and disabling interrupts that an ordinary program will not generate.</p> <p>This may also require linker support so that memory locations (for memory mapped I/O) can be located at the correct addresses for device registers. However some processors use distinct instructions for I/O and there must be some facility for inserting them in the code stream, so in many cases it may not be possible to access H/W unless there is explicit language support.</p> <p>And finally, with most modern operating systems like Windows and Linux, applications are run in virtual memory where program addresses do not match physical address and the programs are usually denied access to the hardware. Code that tries to access hardware when the OS has not granted it specific permissions will generate an interrupt, return to the OS and no longer execute.</p>
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    1. POAre there any languages that talk straight to the hardware and that aren't assembly?
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