8051 Microcontroller Interview questions Q1. What is 8051 Microcontroller ? The Intel 8051 microcontroller is one of the most popular general-purpose microcontrollers in use today. It is an 8-bit family of microcontroller developed by Intel in the year 1981. This microcontroller was also referred to as “system on a chip” because it has 128 bytes of RAM, 4Kbytes of ROM, 2 Timers, 1 Serial port, and four ports on a single chip. 8051 microcontroller allows CPU to work on 8bits of data at a time.n case the data is larger than 8 bits then it has to be broken into parts so that the CPU can process conveniently. Q2. What are registers in Microcontroller ? Register provides a fast way to collect and store data using microcontrollers and processors.If we want to manipulate data with a controller or processor by performing tasks like addition, subtraction, and so on, we cannot do that directly in the memory, in order to perform these tasks we need registers to process and store the data. Micro

  8051 Microcontrollers Architecture 1. 8051 microcontrollers are manufactured by which of the following companies? a) Atmel b) Philips c) Intel d) All of the mentioned Answer: All of the mentioned 2. AT89C2051 has RAM of: a) 128 bytes b) 256 bytes c) 64 bytes d) 512 bytes Answer: 128 bytes 3. 8051 series has how many 16 bit registers? a) 2 b) 3 c) 1 d) 0 Answer: 2 4. When 8051 wakes up then 0x00 is loaded to which register? a) PSW b) SP c) PC d) None of the mentioned Answer: PC 5. When the microcontroller executes some arithmetic operations, then the flag bits of which register are affected? a) PSW b) SP c) DPTR d) PC Answer: PSW 6. How are the status of the carry, auxiliary carry and parity flag affected if the write instruction MOV A,#9C ADD A,#64H a) CY=0,AC=0,P=0 b) CY=1,AC=1,P=0 c) CY=0,AC=1,P=0 d) CY=1,AC=1,P=1 Answer: CY=1,AC=1,P=0 7. How are the bits of the register PSW affected if we select Bank2 of 8051? a) PSW.5=0 and PSW.4=1 b) PSW.2=0 and PSW.3=1 c) PSW.3=1 and PSW.4=1 d)