At 8:12 PM -0400 10/22/02, Donald Keenan wrote: >Does this mean that the act of compiling is always hardware specific? Is >RedHat Linux compiled to work only on Wintel/IBM machines? YellowDog >compiled for mac processors?
Compiling is hardware specific, but a program that is correctly written to a particular API (Application Programming Interface) can be simply compiled to another processor. >Is the "compiling" a kind of encryption AND a way to translate it into a >machine readable form? And the machine readable form is not universal >but hardware specific? It is not encryption, just a translation of the program into a machine readable form. >What about open source code/software? Is this code that is not compiled >and therefore open for enhancement? How does one then make it machine >readable? By using a compiling program? Yes, by compiling. >Are some Unix/Linux programs and software then not "compiled"? >I got a vague and most probably incorrect impression from the article on >Unix that C and C++ was a language developed to move toward platform >independent coding. Am I way off here? Here's where things depart. User software can generally be recompiled easily from platform to platform provide the APIs are the same. However the operating system by necessity must know about the details of the processor and hardware. Usually there are differences in the hardware between different computers, and specific programming must be dome to address this issue. Different CPUs have use different methods to control how they access memory for example. There are very significant differences in how a Pentium III accesses memory compare to a G4. There are even differences between the G4 and G3, and the new G3 from IBM, however these are minor compared to the difference between the Pentium and the PowerPC. It is up to the operating system to handle these differences so that when a program needs memory it is given it. The user program does not have to concern itself with the differences - it asks for memory the same way on a PowerPC as on a Pentium. The operating system designer must write code that knows all about the operating systems details, and this code cannot be moved to other processors without modification. Paul -- G-Books is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Refurbished Drives | -- Check our web site for refurbished PowerBooks | & CDRWs on Sale! | Support Low End Mac <http://lowendmac.com/lists/support.html> G-Books list info: <http://lowendmac.com/lists/g-books.html> --> AOL users, remove "mailto:"; Send list messages to: <mailto:G-Books@;mail.maclaunch.com> To unsubscribe, email: <mailto:G-Books-off@;mail.maclaunch.com> For digest mode, email: <mailto:G-Books-digest@;mail.maclaunch.com> Subscription questions: <mailto:listmom@;lemlists.com> Archive: <http://www.mail-archive.com/g-books%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
