1. Which component of microcontroller architecture best fits the blanks below. a
ID: 1924961 • Letter: 1
Question
1. Which component of microcontroller architecture best fits the blanks below.
a. Accumulators A and B and index registers X and Y compose the ________ in the 68HC12
microcontroller.
b. The memory address of the next instruction to be executed is stored in the __________
c. Instruction bytes for the current instruction stored in the _____________.
d. Data exchanged between Memory and the CPU must pass through __________.
e. After decoding instruction bytes, function/control bits are sent to the __________ for
instruction execution.
f. _____________ stores data and instruction bytes.
g. ______________ provide a microcontroller with interfaces to the outside world.
h. A memory address operand must pass from the CPU to the memory through the __________.
2. Arithmetic Instructions
a) If accA holds $16 and accB holds $2A, what values will be in the each accumulators after executing the ABA instruction?
b) What series of instructions would achieve the 16-bit subtraction of $1234 from $8ABC (i.e., $8ABC-$1234)? Write the instructions and state what the result would be and where it would be stored.
3. Data Transfer/Manipulation Instructions
a) If accA holds $16 and accB holds $2A, what memory locations will change value after executing
the STD $637F instruction? Identify the new value in any changed memory locations.
b) What is the difference between a logical shift right and an arithmetic shift right?
4. Logic and Bit Operations
Assuming Accumulator B holds $FF:
a)What value is in accB after the instruction BITB #$00?
b)What values is in accB after the instruction ANDB #$00?
c)What CCR flags are set or cleared by the instructions in a) and b)?
Assuming accD holds $B5A4, IX holds $833C, and memory location $833C holds $0F:
d) What is the result of the instruction BCLR $E200 %01100110? Specify the resulting value in hex and the location it is stored.
e) Write an instruction that will force high (1) the 5 , 3 and 1 bits of memory location $00D7.
5. Data Test Instructions
Using a data test instruction, how could you determine if an 8-bit values stored in memory address $E207 was negative. Write the required assembly code and explain what happens after the code is executed to let you know if the value is negative or not.
Explanation / Answer
a) 16 bit registers b) program counter (PC) c)memory d)control unit e)ALU
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