1434
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- A hypothetical Machine has the following characteristics:
0 3 4 15
Opcode Address
- Instruction Format 0 1 15 Sign Magnitude
- Integer Format
Program Counter (PC) = Address of Next Instruction, 12-bits Instruction Register (IR) = Instruction being Executed, 16-bits Accumulator (AC) = Temporary Storage, 16-bits Memory Address Register (MAR) = Address of the memory location being accessed next, 12-bit Memory Buffer Register (MBR) = The Data/Instruction brought/being sent to Memory, 16-bits - Internal CPU Registers.
(0001)2 = Load AC from memory
(0010)2 = Store AC to memory
(0101)2 = Add to AC form memory - Partial list of opcodes
CPU Registers Memory PC AC IR 300 – – 1940 5941 2941 300 301 302 0003 0002 940 941 - Initial Position of the Program. All the given values are in hexadecimal format.
- Show in steps the execution of the above program on the hypothetical machine.
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- What is an Instruction cycle? Give the flowchart for the instruction cycle which shows how the control determines the three possible instruction types.
- Explain in detail an Interrupt driven I/O operation.
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- What do you understand by DMA transfer and data? Why does DMA have priority over CPU when both request a memory transfer?
- What are addressing modes of instructions? Explain the various possible addressing modes.
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- Compare zero-, one-, two- and three- address machines by writing programs for each of these four machines to compute the expression:
X = (A + B * C)/(D – E * F)
The instructions available for use for these machines are as follows:
0-Address 1-Address 2-Address 3-Address PUSH M LOAD M MOVE X, Y; X MOVE X, Y; X POP M STORE M ADD X, Y; X ADD X, Y, Z; X ADD ADD M SUB X, Y; X SUB X, Y, Z; X SUB SUB M MUL X, Y; X MUL X, Y, Z; X MUL MUL M DIV X, Y; X DIV X, Y, Z; X DIV DIV M – –
- Compare zero-, one-, two- and three- address machines by writing programs for each of these four machines to compute the expression:
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