Running AIX with 2 GiB of RAM and beyond

Trying to find out how much RAM can be given to a PPC PReP machine. In the IBM 40p the PCI host controller is sitting at 0x80000000, which means that in theory 2 GiB can be easily given:

QEMU PReP/40p, Serial #0, 2 GiB memory installed
Open Firmware, built  June 14, 2020 13:25:09
Copyright (c) 1995-2000, FirmWorks.
Copyright (c) 2014,2017,2019,2020 Artyom Tarasenko.

Rebooting with command: boot /pci/scsi@1/disk@0,0:1
Boot device: /pci/scsi@1/disk@0,0:1  Arguments: 

Saving Base Customize Data to boot disk
Starting the sync daemon
Starting the error daemon
System initialization completed.
Starting Multi-user Initialization
 Performing auto-varyon of Volume Groups 
 Activating all paging spaces 
0517-075 swapon: Paging device /dev/hd6 is already active.

And it even is recognized by AIX 5.1:

AIX Version 5
(C) Copyrights by IBM and by others 1982, 2000.
Console login: root
*******************************************************************************
*                                                                             *
*                                                                             *
*  Welcome to AIX Version 5.1!                                                *
*                                                                             *
*                                                                             *
*  Please see the README file in /usr/lpp/bos for information pertinent to    *
*  this release of the AIX Operating System.                                  *
*                                                                             *
*                                                                             *
*******************************************************************************

#  lsattr -El mem0 
size     2048 Total amount of physical memory in Mbytes  False
goodsize 2048 Amount of usable physical memory in Mbytes False
# 

Now I wonder, there were some 32 bit  RS/6000 machines with 3 GiB RAM, where there any PReP machines among them?

Playing with z/OS on Hercules

My new toy. Initially one of the data sets were damaged, but after all I managed to get the networking, including FTP and SSH work.

TSO login, that's easy

L CICS. Now what?

The 3270 terminals work out of the box. The networing had to be set up.

System log. Finally no red lines.

For some reason ssh is only allowed for the webadm user,  but it's possible to su - ibmuser.

and since OMVS is working, I can ssh

Maybe it's time to learn Cobol now :-)