Processors like MP3000 support ESA/390 mode only. In ESA/390 mode you can address up to 2 GB (Gigabyte) real and virtual storage.. All System z processors (z800, z890, z9, z10 and zEnterprise) support ESA/390 as well as z/Architecture mode. In z/Architecture mode you can access more than 2 GB real and virtual storage - in z/VSE up to 32 GB real and up to 90 GB virtual storage.
z/VSE runs in z/Architecture mode since z/VSE 4.1. To hold the larger addresses (8 byte addresses instead of 4 byte addresses) the location of the interrupt... [More]