Booting an IBM MP 3000 S/390 Syste

[Michael Thompson]

Date: Thu, 6 Aug 2015 18:43:53 +0100
> From: "Dave G4UGM" <dave.g4ugm at gmail.com>
> Subject: RE: Booting an IBM MP 3000 S/390 System
>
> Actually I remember booting an IBM4381 from cold after we shut it down
> over Christmas. Just pressing the Power button powered it up eventually,
> but I am pretty sure it took nearly an hour to get to the IPL prompt. So it
> did disk drives, then tape drives, then other bits and bobs. But when it
> spun up the disks it brought them up one at a time so the startup surges
> didn't trip the main breaker. The same with the tape drives. Then  it
> loaded the microcode into all the controllers. Then it booted the OS. As we
> were running VM this last bit took a few seconds (I think). I do know if VM
> crashed you screen logo frequently re-appeared before you had time to think.
>
> Dave Wade
> G4UGM
>

I have done the same on a Honeywell mainframe. After powering up everything
manually the only the mag tape and card reader I/O controllers had boot
capability. Push the INIT and BOOT buttons and it would read and load tape
controller microcode from mag tape, then read and load the disk controller
microcode, then the processor's boot code, and then boot from disk. It took
just seconds for the mag tape part. Getting the front end processors
bootloaded, and getting online communications, timesharing, and batch
processing up took a while.

This system was capable of booting from binary punched cards. We used to
try it periodically just to make sure that this capability worked.

-- 
Michael Thompson