IBM Enterprise Systems Architecture is an instruction set architecture introduced by IBM as ESA/370 in 1988. It is based on the IBM System/370-XA architecture
although with different register and bit assignments. As IBM added new features to the architecture, e.g., DAS, S/370-XA, S/370-ESA, ESA/390, they added additional
z/Architecture, initially and briefly called ESA Modal Extensions (ESAME), is IBM's 64-bit complex instruction set computer (CISC) instruction set architecture
1988, IBM announced the Enterprise Systems Architecture/370 (ESA/370) for enhanced (E) 3090 and 4381 models. It added sixteen 32-bit accessregisters, more