Download Note 3

iSeries
Note3
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
iSeries architecture
Application programs and OS/400 programs
MI
[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)
Internal details
are hidden
Data
Structure
[encapsulation]
Object
•highly extendable  new environments
System Licensed Internal Code (SLIC) [Knowledge about the hardware characteristics]
Conventional Machine Interface
iSeries MI
Note: There is no
memory at the MI
The System Licensed Internal Code [Kernel]
• The iSeries' operating system  OS/400 [MI] + SLIC
Operating System Functional Split
System-wide security is in OS/400,
while the authorization to system
resources is in the SLIC
Technology-Independent Machine Interface
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
Object-based system
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.
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 plugin 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.