If the address field is non-zero, it is a disk address of the block, which has previously been rolled out, so the block is fetched from disk and the pbit is set to one and the physical memory address updated to point to the block in memory ( another pbit ).
12.
Disk address sizes limit the size of the active S / 36 partition to about 2GB; however, the Advanced / 36 Large Package had a 4GB hard drive which could contain up to three ( emulated ) S / 36s, and Advanced / 36 computers had more memory than SSP could address ( 32MB to 96MB ) which was used to increase disk caching.
