Take a look at the datasheet for a 64Mbit generation SDRAM. It comes in 4 bit, 8 bit and 16 bit versions. The 8 bit version requires 29 signals and can run faster than 100MHz. https://www.micron.com/-/media/client/global/documents/products/data-sheet/dram/64mb_x4x8x16_sdram.pdf