Technology independence, one of IBM I's five major features

Technology independencetechnology independence, one of the five features of IBM I

Unlike other computer systems, IBM I isn't defined by hardware; it's defined by software. this means that a program doesn't "Speak" directly to the hardware; it "speaks" to a technology-independent machine interface. between this interface and the actual hardware are more than four million lines of operating system software called the system licensed internal code (SLIC ).

Ibm I program has no knowledge of the underlying hardware; this knowledge remains entirely within the SLIC. this means that when the processor technology changes, IBM can rewrite the SLIC components that are aware of those technology changes and thus preserve the integrity of the machine interface. because of this technology-independent design, customer application programs are also unaware of technology changes and can exploit new technology without being disrupted by it.

The importance of the technology-Independence Principle was dramatically extends strated When AS/400 processor technology moved from a 48-bit Complex Instruction Set Computer (CISC) design to a 64-bit Reduced Instruction Set Computer (RISC) design. export customers needed merely to save their programs off their CISC machines and restore them on their new RISC machines, and the programs ran as fully 64-bit programs.