2. 0000h is the address of the PC after reset, and the next three are the entry address of external interrupt 0, timer interrupt 0, external interrupt 1, timer interrupt 1, and serial port interrupt

3. It is the allow access to the external memory control line, which is valid at a low level, and is used with the 8031, because the 8031 has no internal program memory so it must be grounded to allow the use of external memory.

4. There are two priority levels of 0 and 1, respectively, through the priority register IP to set, want to set a certain interrupt for the high priority will be the corresponding register position 1.

5. work register area, divided into four groups of general-purpose registers, each group is divided into R0 ~ R7, can be selected through the program status word PSW4 and PSW3 to use which group; bit addressing area, can be bit or byte addressing. Bit addressing area, which can be bit or byte addressing; data buffer stack area, which can set the start of the stack.

6. Not the same, the first is to send the contents of the accumulator in the on-chip register Ri, the second is to send the contents of the accumulator in the off-chip register Ri.

It's exhausting to type, I hope it helps.