Which was a backward-compatible extension of a 48-bit address space system built out of 1970s chips: http://bitsavers.trailing-edge.com/pdf/ibm/system38/IBM_Sys

Which was a backward-compatible extension of a 48-bit address space system built out of 1970s chips: http://bitsavers.trailing-edge.com/pdf/ibm/system38/IBM_System_38_Technical_Developments_Dec1978.pdf http://bitsavers.trailing-edge.com/pdf/ibm/system38/IBM_Syst...