Memory mapped IO is one where the processor and the IO device share the same memory location(memory) while IO mapped IO is one where the processor and the IO device have different memory located to each other.
In memory mapped I/O the I/O devices are mapped(identify for communication) through memory address. The address of the port will stored in memory locations. In I/O mapped I/O devices are mapped using the the port address.
In memory mapped io we use locations of memory interfaced as an address to IO devices whereas in IO mapped IO we use 8-bit address to interface io. In memory mapped io we can use all instructions for data flow whereas in io mapped io we can use only two instructions i.e IN and OUT.
Memory-mapped I/O uses the same address bus to address both memory and I/O devices, and the CPU instructions used are same for accessing the memory and also accessing devices. In order to accommodate the I/O devices, areas of CPU's addressable space must be reserved for I/O.
IN IO mapped IO special class of CPU instructions are used for performing I/O./O devices have a separate address space from general memory, either accomplished by an extra "I/O" pin on the CPU's physical interface, or an entire bus dedicated to I/O.
In memory-mapped I/O single set of read and write lines are used while in I/O mapped I/O different set of read and write lines are used. In memory mapped I/O same set of memory instructions are used whereas in I/O mapped I/O distinct set of instructions are used by input/output device or memory unit. In memory mapped I/O decision making is difficult whereas its easy in later one.
Memory mapped I/o means I/o devices addresses are mapped to memory i.e. these I/O can be accessed like memory and all instructions related to memory can be used with these devices. I/O mapped I/O have uniqe addresses and are called port. I/O mapped I/O uses only two instructions viz IN and OUT. e.g. IN FEh or OUT 7Eh. This means FE h is port number in hexadecimal number system. similarly 7E. These port numbers will be from 00h to FFh.
In memory mapped I/O the I/O devises are mapped same as internal memory devise. Port devises are addressed same as memory and Instructions are also same for both. This is main advantage of memory mapped I/O.
In port I/O the internal memory and I/O devises are mapped (addressed) differently. For fetch I/O devise it used only two instructions IN and OUT.
one of the major difference between I/O mapped and memory-maped interfacing is that in case of i/o mapped all address line cannot be used but among 20 address line atlest 16 are used,but in case of memory-mapped all address line are used.
There is an object that provides one point access to page, request, response, session, out, exception, config and application. What is that object or mechanism? Is it pageContext, if so give an example.