protected mode
32 bit
32-bit flat memory mode.
In real mode, the effective memory address is the same as the linear, or physical, memory address. The segment register operates by specifying the base of a 64kb region of memory, each region overlapping the other by 16 bytes. In protected mode, the effective address is translated by the page table which provides a larger region size and more memory addressibility. The segment register, a/k/a selector, selects the particular page table to use.
Real mode: Real mode, also called real address mode, is an operating mode of 80286 and later x86-compatible CPUs. Real mode is characterized by a 20 bit segmented memory address space (giving just over 1 MB of addressable memory) and unlimited direct software access to all memory and I/O addresses and peripheral hardware. Real mode provides no support for memory protection, multitasking, or code privilege levels. 80186 CPUs and earlier, back to the original 8086, have only one operational mode, which is equivalent to real mode in later chips. All x86 CPUs in the 80286 series and later start in real mode when reset. Protected mode: In computing, protected mode, also called protected virtual address mode,[1] is an operational mode of x86-compatible central processing units (CPU). It allows system software to utilize features such as virtual memory, paging, safe multi-tasking, and other features designed to increase an operating system's control over application software. When a processor that supports x86 protected mode is powered on, it begins executing instructions in real mode, in order to maintain backwards compatibility with earlier x86 processors.Protected mode may only be entered after the system software sets up several descriptor tables and enables the Protection Enable (PE) bit in the Control Register 0 (CR0). Protected mode was first added to the x86 architecture in 1982, with the release of Intel's 80286 (286) processor, and later extended with the release of the 80386 (386) in 1985. Due to the enhancements added by protected mode, it has become widely adopted and has become the foundation for all subsequent enhancements to the x86 architecture. D.Ghosh Roy
In real mode addressing for x86 cpus, memory is addressed with pairs of a segment and offset. The offset is added to the segment address multiplied by 16 to yield a 20-bit (20 binary digits, in other words, from the number 0 to (2^20)-1=1,048,575) address that points to a specific byte (8-bit number) in memory. Real mode is different than protected mode (which is used by Windows 95+, Linux on x86, etc) in that there is no segment protection, no inherent multitasking support, and it is possible to directly access the BIOS interrupts. Note also that the 20-bit address number prevents more than one (1) megabyte of memory from being addressed at a time.
8086 is a 16 bit processor and 80186,80286,80386,80486.Pentium etc are advanced microprocessors with certain additional features like virtual memory,memory management,protection features etc.Also their operating speed,memory capacity etc varies.They will operate in real mode where its like 8086 and virtual mode in which protection features are enabled
To find the memory mode on a Smith Corona XD 6600 typewriter, first, ensure the machine is powered on. Press the "Mode" key until you see "Memory" or "M" displayed on the screen. This indicates that the typewriter is in memory mode, allowing you to use its features for storing and recalling text. Refer to the user manual for more specific instructions on using memory functions.
punched card
Real mode -16bit Protected mode -32bit
The Samsung Moon Mode feature is real.
The differences are given below: 80286 1. Low data bus width (16 bit) 2. Returning from protected mode to real mode is hard and complicated. 3. Small RAM/Memory 80386 1. High data bus width (32 bit) 2. Easy for 80386 3. Big RAM / Memory (Real memory = 4GB and virtual memory= 64TB)