Why is the 8061 microcontroller described as having 256 bytes of internal memory?
Their terminology is sloppy IMO. In any case:
0x00 - 0x0F are specialized registers
0x10 - 0xFF are memory registers (SRAM)
There are only 240 bytes of SRAM. If you need more SRAM than this, you can add more externally via the MBUS.