Now to examine the paths between the CPU core and memory. The RX is based on an enhanced Harvard architecture, with a 64-bit wide dedicated bus for instructions and a 32-bit wide dedicated bus for operands, or data. This is an extremely optimized arrangement. The longest RX instruction is 64 bits and the native data size is 32-bits, but options exist for 8-, 16-, and 64-bit data as well. The data can even reside at odd address boundaries to eliminate wasted space in expensive SRAM. Typically, the instruction bus is connected to Flash memory and the data bus to SRAM. But as will be seen later, it does not always have to be this way since RX has “enhanced” Harvard architecture.