MICROPROCESSOR AND AASEMBLY LANGUAGE PROGRAMMING SUBJECT CODE: MCC102 FIRST SEMESTER EXAMINATION:2013 QUSESTION CODE:C-625 For 1ST SEMESTER, MCA Students BPUT EXAMINATION QUESTION PAPPER SOLUTION NATIONAL INSTITUTE OF SCIENCE AND TECHNOLOGY PALUR HILLS, BERHAMPUR, ODISHA.
SUBJECT CODE: MCC102 1. Answer the following Questions: a) Decode the following ASCII message. 10100111010100101010110001001011001 01000001001000100000110100101000100 ANS: First it needs to convert the binary numbers to decimal. These are 7 bit numbers*(7 numbers in a group) 1010011, 1010100,1010101,1000100,1011001, 0100000, 1001000,1000001,1010010,1000100 Find its equivalent Decimal 83, 84,85,68,89, 32, 72,68,82,68 Now look at the ASCII table: to find the equivalent ASCII code 83 84 85 68 89 32 72 65 82 68 S T U D Y (SPACE) H A R D So decoded ASCII message is: STUDY HARD b) What is the purpose of Flip-Flop? ANS: Flip flop is a circuit that has two states. Flip flop can be used to store the states information. Flip-flops are used as data storage elements, Flip-flops can be used to store one bit, or binary digit, of data. It is used in memory chip & in microprocessor c) What is the role of memory? Classify the memories. ANS: Memory stores such information as instruction & data. It provides the information to microprocessor when needed. To execute the program microprocessor reads instruction and data from memory and performs the computation in its ALU. The computed result may be stored in memory. Memory in the microprocessor is two types: Read Only Memory (ROM) Read/Write Memory (RAM) [NATIONAL INSTITUTE OF SCIENCE AND TECHNOLOGY, BERHAMPUR, ODISHA] Page 1
SUBJECT CODE: MCC102 d) Discuss the significance of flag register employed by different microprocessor. ANS: The flag register is a status register, which contains the current state of the processor.The flags are used for the decision –making process of the microprocessor. The conditions (set or reset) of the flags are tested through software instructions. e) What are the different steps during the read cycle of memory ANS: During memory read cycle microprocessor read the data from memory. These operations required 3T states in 8085 microprocessor i.e. T1 to T3. Read cycle: First the microprocessor sends appropriate status signals to do memory Read operation. The Address is transferred on Address lines depends on the operation. The address is given by instruction. After that data bus is used to transfer the data from the memory to microprocessor. The control signals is used to do read operation f) If typical PC uses a 20 bit address code, how much memory can the CPU address? ANS: If typical PC uses a 20 bit address code, the maximum memory that can be access by CPU is 1MB (1 Mega byte) g) What is a Tri-state Device? ANS: Tri –state logic device have three states: Logic 1, logic 0, and high impedance. A tri-state logic device has third line called Enable with input and output line. When Enable line is activated the tri state device functions same as an ordinary logic device. When Enable line is disabled the logic device goes in to high impedance state. (As it is disconnected from system).In high impedance state practically no current is drawn from systematic state means three states of operation. Usually it is used on data buss whereby data is transferred to peripheral devices called the buss goes to open state which makes a tri state device. [NATIONAL INSTITUTE OF SCIENCE AND TECHNOLOGY, BERHAMPUR, ODISHA] Page 2
SUBJECT CODE: MCC102 h) What will be the content of PC after the execution of RST 6 instruction? ANS: The content of PC after the execution of RST 6 instruction is 0030H i) What will the status of CY flag after execution of CMP L instruction? ANS: CMP L instruction will compare the content of Accumulator (A) and L register and comparison is shown by setting flags. So there are three possible conditions If Content of (A) > content of L: CY flag = 0 If Content of (A) < content of L: CY flag = 1 If Content of (A) = content of L: CY flag = 0 j) What is DMA data Transfer? ANS: DMA Stands for "Direct Memory Access." DMA is an I/O technique commonly used for high speed data transmission. DMA is allows devices to transfer data without subjecting the CPU to a heavy overhead. Otherwise, the CPU would have to copy each piece of data from the source to the destination, making itself unavailable for other tasks. In DMA the MPU releases the control of the Busses to device called DMA Controller. The controller manages the transfer between memory and a peripheral under its control, thus bypassing the MPU. In 8085 it use HOLD and HLDA to do DMA operation. 2. a) Convert the following octal numbers directly to Hexadecimal numbers without converting to decimal. I. 5525 [NATIONAL INSTITUTE OF SCIENCE AND TECHNOLOGY, BERHAMPUR, ODISHA] Page 3