What is a real regime?

Real Mode is an address and operating scheme for computer microprocessors. In real mode, there is no memory that can be accessed by the program - usually with random access memory (RAM) - in any way managed or equalized by hardware, software or basic input and output services (BIOS). This means that the program is able to access all reachable memory addresses, no matter what the memory is used for, and has to manage all aspects of reading and writing on memory. Several restrictions come with the use of Real Mode, including the fact that the amount of memory available is limited to 1 megabyte, because the processor in this mode allows only 20 bits. From a practical point of view, computer software no longer uses real mode because it has been replaced by a more secure, more expandable and flexible addressing mode known as a protected mode.

Thecentral processorA computer (CPU) of a computer is a place where real mode can be activated, and most aspects of the regime are actually dealing with the problems that usually appear in applications written in the assembly, because they are quite atomic in nature. The processor chips, which are based on the original 8086 architecture, start in real mode when powered to run programs that were written for earlier hardware, even if it would often require emulation software to be successful. The protected mode almost completely replaced the actual addressing, since 2011, to a point where there are very few compiler, which can even compile a program that can use real addressing and even fewer main operating systems that could run it.

Memory

in real mode is basically the only one, the linear sequence of the bytes that can be freely accessed using an address composed of a 16 -bit segment address and a 4 -bit offset in the segment, creating a complete 20 -bit ADRace. The program can approach any point in memory and read or write anything, no matter what is in place. This means that without proper management and knowledge, the program using the actual addressing mode could easily rewrite the operating system and system BIOS, start the interruption of physical hardware or randomly send a signal to the peripheral device. Not only could this cause the system to freeze or freeze, but it could also cause data loss or physical damage to hardware.

As soon as the protected processor architecture, the protected mode eventually replaced the real mode in almost all software. Over time, the use of actual addressing mode has become unnecessary because it was unable to approach more than 1 megabyte RAM and could not use more than 20 bits of system bus, which means that it could only use a fraction of resources available on most computers. Real addressing also represents a significant security risk. One of the few ways to write a program that usesA real addressing mode is the use of the report language to and do the program within the special disk operating system (DOS) that does not automatically switch to the protected mode when starting.