E.g. mmc1 from what I have read I understand that there are 4 cart internal registers each of which are 5 bits in length! well from what I gather they are really 8 bit 1 byte word registers with 5 bits of useful information and the 8th bit is the reset bit.???? am I correct or not.

and also from what I have read and though about - mmc1 has 1 cart (internal) shift register (buffer) which then stores that information into the appropriate register?? - hardware point of view, or are all the registers simply 8 bit shift registers.. or somthing like that