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. Source: CoolInterview.com
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. Source: CoolInterview.com
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. Source: CoolInterview.com
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. Source: CoolInterview.com
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.