The 8051 Microcontroller Questions

• 8051 ports and alternate functions — what is the alternate function of port pin P3.0 (labelled RXD)? Choose the correct role of P3.0 within the on-chip serial interface.
• 8051 direct addressing — does the instruction 'MOV 23H, A' copy the Accumulator to internal RAM address 23H? Decide whether this statement about direct-address destination is correct.
• 8051 reset and code fetch source — with EA held LOW at reset, where does the Program Counter fetch the first instruction from? Select the memory space the CPU uses immediately after reset when EA = 0.
• 8051 addition syntax — which statement correctly adds register R3 to the Accumulator and stores the result back in A? Choose the valid 8051 ADD form that implements A ← A + R3.
• 8051 register moves — which instruction copies the contents of the Accumulator into register R6? Select the correct MOV form that implements R6 ← A.
• 8051 subroutine control flow — does the statement 'LCALL READ' transfer execution to the line labelled READ? Judge whether LCALL followed by a label calls that subroutine and saves the return address.
• 8051 external data memory access — is data transfer to/from external RAM possible only via the MOVX instruction? Evaluate whether external data memory reads/writes require MOVX (with DPTR or @R0/@R1 as pointer).
• 8051 loop behavior — will the following code execute continuously (infinite loop)? Code at label STAT: STAT: MOV A, #01H JNZ STAT Decide whether execution remains stuck at STAT forever.
• 8051 reset input — which active-HIGH pin resets the microcontroller when driven HIGH for a proper pulse width? Select the correct pin name used to reset a standard 8051.
• ADC0804 start-of-conversion control In the ADC0804 successive-approximation ADC, which hardware input is used to initiate (start) a conversion, assuming chip select (CS) is asserted appropriately?
• 8051 memory spaces overview Is it correct that the 8051 architecture divides address space into four distinct areas: internal data, external data, internal code, and external code?
• Assembly source notation In assembly language programming, is a label primarily used to name the address (location) associated with a single line/instruction so it can be referenced elsewhere?
• 8051 register-to-accumulator move Which 8051 instruction correctly moves the contents of register R3 into the accumulator A?
• The 8051 is a 40-pin IC. Twenty-two pins are needed for the four I/O ports.
• Different instruction sets must make up for the various members of the 8051 family.
• The RST pin requires a HIGH to reset the 8051 microcontroller.
• Up to 65K of code memory and 65K of data memory can be added to any of the 8051 family members.
• In an 8051 program DA A adjusts the value in the accumulator resulting from an addition into two BCDs.
• Writing counter/loop programs is much more difficult with the introduction of the DJNA and the CJNE instructions.
• Analog output current must be converted into a usable voltage. To perform this current-to-voltage conversion a 700 op amp may be used.