Alu Data Path and Control Unit · Computer Organization · GATE CSE

Consider the following data path diagram.
Consider an instruction: R0 $$ \leftarrow $$ R1 + R2. The following steps are used to execute it over the given data path. Assume that PC is incremented appropriately. The subscripts r and w indicate read and write operations, respectively.

1. R2_r, TEMP1_r, ALU_add, TEMP2_w
2. R1_r, TEMP1_w
3. PC_r, MAR_w, MEM_r
4. TEMP2_r, R0_w
5. MDR_r, IR_w

Which one of the following is the correct order of execution of the above steps?

Consider the following processor design characteristics.

$$\,\,\,\,\,\,\,{\rm I}.\,\,\,\,\,$$ Register-to-register arithmetic operations only
$$\,\,\,\,\,{\rm I}{\rm I}.\,\,\,\,\,$$ Fixed-length instruction format
$$\,\,\,{\rm I}{\rm I}{\rm I}.\,\,\,\,\,$$ Hardwired control unit

Which of the characteristics above are used in the design of a $$RISC$$ processor?

The size of the data count register of a $$DMA$$ controller is $$16$$ bits. The processor needs to transfer a file of $$29,154$$ kilobytes from disk to main memory. The memory is byte addressable. The minimum number of times the $$DMA$$ controller needs to get the control of the system bus from the processor to transfer the file from the disk to main memory is ___________.

Consider the following sequence of micro-operations
$$\eqalign{ & \,\,\,\,\,\,\,\,\,\,\,\,\,MBR\,\,\,\,\,\,\, \leftarrow PC \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,MAR\,\,\,\,\,\,\, \leftarrow X \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,PC\,\,\,\,\,\,\,\,\,\,\,\, \leftarrow Y \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,Memory\, \leftarrow MBR \cr} $$

Which one of the following is a possible operation performed by this sequence?

Consider the following data path of a $$CPU$$

The, $$ALU$$, the bus and all the registers in the data path are of identical size. All operations including incrementation of the $$PC$$ and the $$GPRs$$ are to be carried out in the $$ALU.$$ Two clock cycle are needed for memory read operation-the first one for loading address in the $$MAR$$ and the next one for loading data from the memory but into the $$MDR.$$

The instruction $$''add$$ $$R0$$, $$R1''$$ has the register transfer interpretation $$R0 < = R0 + R1.$$ The minimum number of cycles needed for execution cycle of this instruction is

Consider the following data path of a $$CPU$$

The, $$ALU$$, the bus and all the registers in the data path are of identical size. All operations including incrementation of the $$PC$$ and the $$GPRs$$ are to be carried out in the $$ALU.$$ Two clock cycle are needed for memory read operation-the first one for loading address in the $$MAR$$ and the next one for loading data from the memory but into the $$MDR.$$

The instruction $$''call$$ $$Rn,sub''$$ is a two word instruction. Assuming that $$PC$$ is incremented during the fetch cycle of the first word of the instruction, its register transfer interpretation is $$$\eqalign{ & Rn < = PC + 1; \cr & PC < = M\left[ {PC} \right]; \cr} $$$
The minimum number of $$CPU$$ clock cycles needed during the execution cycle of this instruction is :

The microinstructions stored in the control memory of a processor have a width of $$26$$ bits. Each microinstruction is divided into three fields: a micro-operation of $$13$$ bits, a next address field $$(X),$$ and a $$MUX$$ select field $$(Y).$$ There are $$8$$ status bits in the inputs of the $$MUX$$.

How many bits are there in the $$X$$ and $$Y$$ fields, and what is the size of the control memory in number of words?

Horizontal micro programming

Arrange the following configuration for CPU in decreasing order of operating speeds: Hardwired control, vertical micro- programming, horizontal micro-programming

Consider the following datapath of a simple non-pipelined $$CPU.$$ The registers $$A,B,$$ $${A_1},{A_2},$$ $$MDR,$$ the bus and the $$ALU$$ are $$8$$-bit wide. $$SP$$ and $$MAR$$ are $$16$$-bit registers. The $$MUX$$ is of size $$8 \times \left( {2:1} \right)$$ and the $$DEMUX$$ is of size $$8 \times \left( {1:2} \right)$$. Each memory operation takes $$2$$ $$CPU$$ clock cycles and uses $$MAR$$ (Memory Address Register) and $$MDR$$ (Memory Data register). $$SP$$ can be decremented locally.

The $$CPU$$ instruction $$''push$$ $$r'',$$ where $$r=A$$ or $$B,$$ has the specification
$$\eqalign{ & \,\,\,\,\,\,\,\,\,\,\,\,\,M\left[ {SP} \right] \leftarrow r \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,SP \leftarrow SP - 1 \cr} $$
How many $$CPU$$ clock cycles are needed to execute the $$''push$$ $$r''$$ instruction?

The main difference (s) between a $$CISC$$ and a $$RISC$$ processor is/are that a $$RISC$$ processor typically: