LPAR, Upgrades, New Hardware

["Joe Pluta" <joepluta@xxxxxxxxxxxxxxxxx>]

> From: Larry Bolhuis
>
>   As you no doubt know there are only two ways for an 'old' OS to run on
> a 'new' piece of hardware. a) the hardware emulates older hardware
(...)
> or the software gets a boost to support the new hardware.

No, there's a third option, the concept of writing to a virtual machine
layer.  If your operating system talks to a virtualized hardware layer
rather than directly to the hardware, then all you need to rewrite is the
VM.  This is the concept that has made Java so successful, and is the same
thing that the AS/400 uses, as IBM itself says:

"Both Java and AS/400 are based on the same fundamental principle. The
source code is converted to an intermediate form that runs on a virtual
machine so that even if the underlying hardware machine changes
significantly (in the AS/400 case), or is purposely abstract so that it can
be any underlying machine architecture (Java), the source code need never be
recompiled to run on this new machine."

The page this came from is actually pretty interesting reading:

http://www-1.ibm.com/servers/eserver/iseries/whpapr/dev_toolkit_java.html


>From what I understand, the TIMI is the "Technology Independent Machine
Interface", which should not change from hardware to hardware, and the SLIC
is the part that changes.  By adapting the SLIC to the new hardware, you
should theoretically be able to support previous releases with no problems.

Joe