Booting an IBM MP 3000 S/390 System

Guy Sotomayor ggs at
Thu Aug 6 12:41:41 CDT 2015

In many cases more than one!  ;-)

But more to the point, having a separate processor handing the booting 
chores frees the
main CPU from those tasks.  Initialization can be a pain just look at 
the x86 ISA and the
hoops it makes the S/W (BIOS & OS) just to get to the point where the OS 
can really start
it's own initialization!  And that doesn't even cover the "magic" that 
goes on just so that
the x86 CPU can fetch the first instruction.

As folks have mentioned, a lot of larg(er) system have service 
processors to handle the
booting chores.  However, it's more than that.  The service processor 
(as the name
implies) is doing a whole lot more than just booting.  It is also 
responsible for running
low level diagnostics and capturing the results of hard crashes for 
later diagnosis.

For example, the RS/6000 series, had a service processor.  It was even 
responsible for
loading the OS kernel image into RAM.  This made the OS's like much easier.

Back to the MP 3000.  There are a number of CPUs in the box.  Two are 
the most
obvious: the SBC running OS/2 and the actual S/390 CPU.  However, there 
is another
S/390 CPU in the box as well.  It is not visible (at least directly) to 
S/W.  It is responsible
for providing the high performance I/O capabilities (like native disk 
access and making
them appear as conventional channel attached devices instead of RAID-5 
SSA drives).
The OS/2 SBC is there to emulate some of the slower devices (card 
direct attached 3270s, etc).

TTFN - Guy

On 8/6/15 10:07 AM, Lee Courtney wrote:
> Even modern SOCs and the processor in your PC/laptop have a
> micro-controller or PMIC that brings ups the rest of the chip. In the PC
> case (verses mainframe) it is on the same die and fabric as the CPU (and
> the scads of other CPUs, GPUs, Sensor Hubs, vision processors, etc).
> Lee C.
> On Thu, Aug 6, 2015 at 9:24 AM, Chuck Guzis <cclist at> wrote:
>> On 08/06/2015 08:04 AM, Sean Caron wrote:
>> If you think the MP3000 is a slow booter, we just got some new 4U
>>> machines in where I work; 1.5TB RAM; those things take almost 20
>>> minutes to POST - no joke!
>> Booting an old CDC 6000-series machine meant mounting a "deadstart" tape,
>> pushing the button just below the screens on the DD60, entering or editing
>> the equipment status table, then going out for a smoke (not me) or a cup of
>> coffee, while the system copied the deadstart tape to disk.  The next
>> prompt was to enter the date and time.
>> People are too impatient today.
>> --Chuck

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