With the aid of flowcharts, distinguish between conditional and unconditional jump instructions.

Here are the solutions to the questions from the image:

(c) With the aid of flowcharts, distinguish between conditional and unconditional jump instructions.

• Conditional Jump Instruction: A conditional jump instruction alters the program flow only if a specific condition is met (e.g., a flag is set or cleared, or a comparison result is true). If the condition is true, the program jumps to a new address; otherwise, it continues to the next instruction in sequence.

  \begin{tikzpicture}[node distance=1.5cm, auto] \node (start) [startstop] {Start}; \node (condition) [decision, below of=start] {Condition Met?}; \node (jump) [process, right of=condition, xshift=2cm] {Jump to Target Address}; \node (next) [process, below of=condition] {Execute Next Instruction}; \node (end) [startstop, below of=next] {End}; \draw [arrow] (start) -- (condition); \draw [arrow] (condition) -- node {Yes} (jump); \draw [arrow] (condition) -- node {No} (next); \draw [arrow] (jump) |- (end); \draw [arrow] (next) -- (end); \end{tikzpicture}

• Unconditional Jump Instruction: An unconditional jump instruction always alters the program flow to a new specified address, regardless of any conditions or flag states. The program execution simply transfers to the target address.

  \begin{tikzpicture}[node distance=1.5cm, auto] \node (start) [startstop] {Start}; \node (jump) [process, below of=start] {Jump to Target Address}; \node (execute) [process, below of=jump] {Execute Instruction at Target Address}; \node (end) [startstop, below of=execute] {End}; \draw [arrow] (start) -- (jump); \draw [arrow] (jump) -- (execute); \draw [arrow] (execute) -- (end); \end{tikzpicture}

SECTION B: MICROCONTROLLER TECHNOLOGY

(a) Describe each of the following Intel 8051 microcontroller special function registers:

• (i) PSW (Program Status Word): This is an 8-bit register that holds various status flags and control bits. It includes the Carry Flag (C), Auxiliary Carry Flag (AC), Overflow Flag (OV), Parity Flag (P), and two general-purpose flags (F0, F1). It also contains the Register Bank Select bits (RS0, RS1) which determine which of the four register banks (R0-R7) is currently active.
• (ii) TCON (Timer Control Register): This is an 8-bit register used to control and monitor the 8051's two 16-bit timers/counters (Timer 0 and Timer 1) and external interrupts. It contains bits for starting/stopping timers (TR0, TR1), timer overflow flags (TF0, TF1), and external interrupt flags (IE0, IE1) and type control (IT0, IT1).
• (iii) IP (Interrupt Priority Register): This is an 8-bit register that allows the user to set the priority level for each of the 8051's interrupt sources. Each bit in the IP register corresponds to a specific interrupt source; setting a bit assigns a higher priority to that interrupt, while clearing it assigns a lower priority.

(b) Explain each of the following Intel 8051 microcontroller instructions, citing the addressing mode in each case:

• (i) MOV A, #50 H;
  • Explanation: This instruction moves the immediate 8-bit hexadecimal value $50\text{H}$ into the Accumulator (A) register.
  • Addressing Mode: Immediate Addressing.
• (ii) MOV C A, @A + DPTR;
  • Explanation: This instruction moves a single bit from the external code memory into the Carry flag (C). The 16-bit address in code memory is calculated by adding the 8-bit content of the Accumulator (A) to the 16-bit content of the Data Pointer (DPTR). This is typically used for reading data from lookup tables stored in program memory.
  • Addressing Mode: Indexed Addressing (Code Memory).
• (iii) DEC @ R1.
  • Explanation: This instruction decrements the 8-bit content of the internal RAM location whose address is stored in register R1. For example, if R1 contains $30\text{H}$, the content of RAM location $30\text{H}$ will be decremented by 1.
  • Addressing Mode: Indirect Addressing.

(c) An array of 10 numbers is stored in the Intel 8051 microcontroller RAM starting at location 30 H. Write an assembly language program to move the array to memory locations starting from 80 H.

          ORG 0000H    ; Start program at address 0000H

          MOV R0, #30H ; Initialize R0 as source pointer (starting at 30H)
          MOV R1, #80H ; Initialize R1 as destination pointer (starting at 80H)
          MOV R2, #10  ; Initialize R2 as a counter for 10 numbers

LOOP:     MOV A, @R0   ; Move data from source address (pointed by R0) to Accumulator
          MOV @R1, A   ; Move data from Accumulator to destination address (pointed by R1)
          INC R0       ; Increment source pointer to the next byte
          INC R1       ; Increment destination pointer to the next byte
          DJNZ R2, LOOP; Decrement R2 and jump back to LOOP if R2 is not zero
          HLT          ; Halt the program