From: black.hole.4.spam{at}gmail.com (Don Hills)

In article , "Geo"
 wrote:
>Does this system have a "maintenance mode"? How do you put
the system into
>that mode?

You have to be there in the machine room. It has a PC under the covers that
acts as the service processor. I'm not sure about the present day but up
until 1999 the service processor ran OS/2. It usually has a modem attached,
outgoing only so it can call in faults to IBM as it finds them.

As for having a "maintenance mode", you can IML it with
diagnostics if you have it to yourself but normal diagnostic and repair
work is done with the processor running - you take the section of the
complex that you need to work on offline via the service console and the
machine just runs a bit slower until you put it back online. It's very
uncommon to have to take the whole machine down for maintenance. It's part
of the "z" in zSeries.

As an aside, IBM PS/2 systems inherited the same design philosophy. In
their heyday, memory was less reliable than it is now. They had the ability
to lock out a defective page (4 KB) of memory "on the fly" and
remap over the gap, provided that the OS had an appropriately enabled TRAP
0002 handler.

--
Don Hills    (dmhills at attglobaldotnet)     Wellington, New Zealand
"New interface closely resembles Presentation Manager,
 preparing you for the wonders of OS/2!"
    -- Advertisement on the box for Microsoft Windows 2.11 for 286

--- BBBS/NT v4.01 Flag-5