The standard arrangement for a 4004 system is anything up to 16 × 4001 ROM chips (in a single bank) and 16 × 4002 RAM chips (in four banks of four), which together provide the 4KB program storage, 1024 + 256 nibbles of data/status storage, plus 64 output and 64 input/output external data/control lines (which can themselves be used to operate, e.g. a 4003). Intel's MCS-4 documentation, however, claims that up to 48 ROM and RAM chips (providing up to 192 external control lines) "in any combination" can be connected to the 4004 "with simple gating hardware", but declines to give any further detail or examples of how this would actually be achieved.