The VAX-11/780 originally supported up to 8MB of memory through one or two MS780-C memory controllers, with each controller supporting between 128kB-4MB of memory. The later MS780-E memory controller supported 4MB-64MB of memory, allowing the VAX-11/780 to support up to a total of 128MB of memory. The KA780 has a 29-bit physical address space, allowing it to address a theoretical maximum of 512MB of memory. The memory is constructed from 4 or 16 kbit metal oxide semiconductor (MOS) RAM chips mounted on memory array cards. Each memory controller controls up to 16 array cards. The memory is protected by error correcting code (ECC).