Changes
Z80
,/* Registers */
| I (Interrupt Vector) || 8-bit || Holds base address for interrupt mode 2 || Combined with external data to form an interrupt vector
|-
| R (Memory Refresh) || 8-bit || Increments after each M1 cycle (instruction or prefix fetch) to refresh DRAM || Only the lower 7 bits are incremented. Bit7 can only be changed by writing to the R register.
|}
