1. iSeries Note3

2. Technology independence Technology independence  change the underlying hardware architecture and add new functionality without disrupting customers. Other manufacturers found ways to incorporate new functions and new hardware designs. Difference  existing application programs cannot use these new capabilities. Intel [1985]  added 32-bit extensions to the original 16-bit architecture. –Any 16-bit application could still run on the new 32-bit chips, but it ran in a 16-bit mode that did not use any of the 32-bit extensions. Intel [1997] made a significant change to the architecture when it added the multimedia extension (MMX). –Older applications could run on the new chips but just couldn't use MMX. PC industry  acceptable to require applications to be rewritten to use the newest hardware functionality

3. iSeries architecture Application programs and OS/400 programs M I [a logical, not a physical, interface to the system] MI architecture has two components – a set of instructions and the operands upon which those instructions act bit and byte operands + data structures [Objects] application program interfaces (APIs) highly extendable  new environments System Licensed Internal Code (SLIC) [Knowledge about the hardware characteristics] Data Structure Object Internal details are hidden [encapsulation]

4. Conventional Machine Interface

5. iSeries MI Note: There is no memory at the MI

6. The System Licensed Internal Code [Kernel] The iSeries' operating system  OS/400 [MI] + SLIC

7. Operating System Functional Split System-wide security is in OS/400, while the authorization to system resources is in the SLIC

8. Technology-Independent Machine Interface

9. Objects how the iSeries uses objects. iSeries is an object-based system [no inheritance] This permits only iSeries servers to make technology advances in the hardware, such as storage, memory, and processor technology, while protecting end-users' investments in existing applications

10. Object-based system

11. Logical partitions and many operating systems iSeries is the universal server. OS/400 Linux Unix, Windows applications all run on iSeries servers. A single server may optionally be divided into several partitions, each of which receives a dedicated set of resources, including processor and memory. The primary partition must be OS/400, but the other partitions can run, as of this writing, different versions of OS/400 and Linux.

12. Logical partitions and many operating systems (cont.) Linux distributions, provided by several vendors, run in logical partition(s) of an iSeries server. Windows applications run on an iSeries server on an optional plug- in Intel processor. Rather than run an instance of a Unix operating system, applications from AIX run inside an OS/400 job, completely and seamlessly integrated into OS/400. –This option is the OS/400 Portable Application Solution Environment (OS/400 PASE). PASE provides a very easy way to drop in, often unmodified, a Unix application on iSeries.