8255 Microprocessor Question & Answers December 31, 2022 By WatElectronics This article lists 100 8255 Microprocessor MCQs for engineering students. All the 8255 Microprocessor Questions & Answers below include a hint and a link wherever possible to the relevant topic. This is helpful for users who are preparing for their exams, or interviews, or professionals who would like to brush up on the fundamentals of 8255 Microprocessor. The 8255 is a programmable peripheral interface, programmable means we can write programs in 8255, peripheral means that I/O device, and interface means a path providing communication between the two components. The 8255 microprocessor is very flexible, versatile, and very economical but its circuitry is complex. The 8255 programmable peripheral interface has 24 I/O lines that are divided into three ports they are ports A, B, and C. Each port has 8 lines and these eight lines act as either input lines or output lines. In the 8255 programmable peripheral interfaces, the pins D0-D7 are used for data transfer with MPU, transfer of control words to PPI, and reading status information from PPI. Mode 0-basic I/O, mode 1-strobe input/strobe output, and mode 2- two-way bus are the basic modes of operations that can be selected by control words. The mode2 (strobed bidirectional bus I/O) is used in group A only, both input and output are latched in mode2. The interfacing between stepper motors and DC motors, generating square waves, traffic light control, etc are the applications of 8255. The output buffer full and input buffer full are other names for the handshake event. The handshake event and handshake trigger are the two types of handshaking signals supported by 8255. 1). In how many modes does 8255 ports are operated? One Two Three Four None Hint 2). Which one of the following pins in 8255 used for data transfer with MPU? PA0-PA7 PB0-PB& D0-D7 None of the above None Hint 3). The operating frequency of 8253 programable interval timer is __________________? 0-2.6 MHz 0-10 MHz 0-1 MHz 0-5 MHz None Hint 4). Which one of the following modes is a bidirectional mode of 8255A? Mode 0 Mode 1 Mode 2 None of the above None Hint 5). In which one of the following programmable interval timers the read back command is not available? 8254 8253 8086 80386 None Hint 6). Which one of the following is also called an input buffer full? Handshake trigger Handshake event Both a and b None of the above None Hint 7). Which one of the following pins used to setup the chip in 8255? Read/write control logic Data bus buffer Control register None of the above None Hint 8). Which one of the following comes under control line pins of 8255? RD pin CE pin RST pin All of the above None Hint 9). Which one of the following IO modes is a unidirectional data transfer with handshaking? Mode 0 Mode 1 Mode 2 None of the above None Hint 10). The operating frequency of 8254 programable interval timer is __________________? 0-2.6 MHz 0-10 MHz 0-1 MHz 0-5 MHz None Hint 11). Which one of the following are latched in mode 0 of 8255 microprocessor? Outputs Inputs Both a and b None of the above None Hint 12). If CS, A0, A1 are zero then which one of the following ports we have to select? Port B Port A Port C None of the above None Hint 13). The ‘A’ is the typical assembly language opcode of ________________ operation? Add memory to register Add (decimal) memory to register Multiply register by memory Multiply (decimal) register by memory None Hint 14). The load from memory location into a register is the description of ______________ mnemonic? ADD SUB STR LDR None Hint 15). Which one of the following comes under power line pins of 8255? RD pin CE pin RST pin VCC None Hint 16). How many bits of control word does 8255 have? 4 bits 2 bits 8 bits 16 bits None Hint 17). The D7 bit of control word in 8255 justifies _______________ modes? IO mode BSR mode Both a and b None of the above None Hint 18). Which one of the following bits in 8255 control word is an upper nibble of port C? D7 bit D3 bit D0 bit D1 bit None Hint 19). The figure shown below is a block diagram of ________________ microprocessor? 8086 80386 80486 8255 None Hint 20). Which one of the following modes is a strobed I/O mode of 8255A? Mode 0 Mode 1 Mode 2 None of the above None Hint 21). The ‘AP’ is the typical assembly language opcode of ________________ operation? Add memory to register Add (decimal) memory to register Multiply register by memory Multiply (decimal) register by memory None Hint 22). If D3 bit is one then the upper nibble of port c works as ________________? Input Output Both a and b None of the above None Hint 23). The port C in 8255 control word used as handshaking for which mode? Mode 0 BSR mode Mode 1 None of the above None Hint 24). In which one of the following, the decoding is more expensive? IO mapped IO Memory mapped IO Both a and b None of the above None Hint 25). Which one of the following IO modes is a bidirectional data transfer with handshaking? Mode 0 Mode 1 Mode 2 None of the above None Hint 8255 Microprocessor MCQ for Quiz 26). In which one of the following IO, the hardware cost is high? Port based IO Memory mapped IO Both a and b None of the above None Hint 27). he 8003H is the sample address for ________________ port? Port A Port B Port C Control register None Hint 28). The figure shown below is a pin diagram of ________________ microprocessor? 8086 80386 80486 8255 None Hint 29). The store values from register into memory location is the description of _____________ mnemonic? ADD SUB STR LDR None Hint 30). Which one of the following modes is a simple I/O mode of 8255A? Mode 0 Mode 1 Mode 2 None of the above None Hint 31). The 7NQ4 is an example for __________________ operation? Less or equal Equal Greater or equal Not equal None Hint 32). The ‘M’ is the typical assembly language opcode of ________________ operation? Add memory to register Add (decimal) memory to register Multiply register by memory Multiply (decimal) register by memory None Hint 33). If a bit is one in D7 control word then 8255 works in _______________ mode? IO mode BSR mode Both a and b None of the above None Hint 34). Which one of the following bits define the mode of port B? D0 bit D1 bit D2 bit D3 bit None Hint 35). In IO mapped IO the data transfer between __________________? Register and IO IO and accumulator Both a and b None of the above None Hint 36). The 8255 programmable peripheral interface has ___________________ eight bits? One Two Three Four None Hint 37). The figure shown below is a ________________ PPI in mode 0? 8086 80386 80486 8255 None Hint 38). In which one of the following IO the memory instructions are used? IO based IO Memory mapped IO Both a and b None of the above None Hint 39). In which one of the following the decoding is easier? IO mapped IO Memory mapped IO Both a and b None of the above None Hint 40). How many pins does 8255 microprocessors has? 40 pins 64 pins 24 pins 20 pins None Hint 41). If CS=0, A1=A0=1 then which one of the following ports we have to select? Port B Port A Port C Control register None Hint 42). The ‘MP’ is the typical assembly language opcode of ________________ operation? Add memory to register Add (decimal) memory to register Multiply register by memory Multiply (decimal) register by memory None Hint 43). The compare values in a register are the description of _____________ mnemonic? CMP SUB STR LDR None Hint 44). The port A in 8255 functions with __________________ modes? Mode 0 Mode 1 Both a and b None of the above None Hint 45). Which one of the following port works with only mode 0 and mode 1? Port A Port B Port C None of the above None Hint 46). Which one of the following bits define the mode of port A? D5 bit D6 bit D4 bit Both a and b None Hint 47). The read and write are the terminals of ________________ block in 8255 block diagrams? Data bus buffer Read write logic Both a and b None of the above None Hint 48). Which one of the following controlled by bit set reset of PC4? INTE A INTE B Both a and b None of the above None Hint 49). The figure shown below is a mode 1 port A of __________________ microprocessor? 8086 80386 80486 8255 None Hint 50). In which one of the following programmable interval timers the write and read of same counter is not be interleaved? 8254 8253 8086 80386 None Hint 8255 Microprocessor MCQ for Exams 51). The 7NE4 is an example for __________________ operation? Less or equal Less than Greater or equal Not equal None Hint 52). The ‘S’ is the typical assembly language opcode of ________________ operation? Subtract memory from register Subtract (decimal) memory from register Move (numeric) from register to memory Move (numeric) from register to memory Compare memory to register None Hint 53). The bitwise logical not operation is the description of _____________ mnemonic? CMP SUB STR MVN None Hint 54). The D6 and D5 bits in 8255 control word defines mode of port ________________? Port A Port B Port C None of the above None Hint 55). In which one of the following modes does port B doesn’t work? Mode 1, mode 0 Mode 2 BSR mode Both b and c None Hint 56). The 8002H is the sample address for ________________ port? Port A Port B Port C None of the above None Hint 57). Which one of the following one used for handshaking in port B? Port A Port B PCL PCU None Hint 58). The figure shown below is a mode 1 port B of __________________ microprocessor? 8086 80386 80486 8255 None Hint 59). Which one of the following bits in 8255 control word is a lower nibble of port c? D0 bit D1 bit D2 bit D3 bit None Hint 60). Which one of the following is also called an acknowledge input? Handshake trigger Handshake event Both a and b None of the above None Hint 61). The 7GT4 is an example for __________________ operation? Less or equal Less than Greater or equal Greater than None Hint 62). The ‘SP’ is the typical assembly language opcode of ________________ operation? Subtract memory from register Subtract (decimal) memory from register Move (numeric) from register to memory Compare memory to register None Hint 63). Which one of the following one used to stop the program? CMP SUB STR HALT None Hint 64). If a bits D6 and D5 bits are 00 then port A will be in _________________ mode? Mode 1 Mode 0 Mode 2 None of the above None Hint 65). In memory mapped IO, the data transfer between _________________? IO and accumulator Register and IO Both a and b None of the above None Hint 66). The 8000H is the sample address for ________________ port? Port A Port B Port C None of the above None Hint 67). Which one of the following controlled by bit set reset of PC2? INTE A INTE B Both a and b None of the above None Hint 68). The mode 2 of ___________________ 8255 microprocessors used for handshaking in PA? PCU PCL Both a and b None of the above None Hint 69). Which one of the following, Io devices can be accessed by any memory instructions? IO mapped IO Memory mapped Io Both a and b None of the above None Hint 70). Which one of the following pins is an interface between CPU and 8255? Read/write control logic Data bus buffer Control register None of the above None Hint 71). If CS & A0 are zero, A1 is one then which one of the following ports we have to select? Port B Port A Port C None of the above None Hint 72). The 7GE4 is an example for __________________ operation? Less or equal Less than Greater or equal Greater than None Hint 73). The ‘MVN’ is the typical assembly language opcode of ________________ operation? Subtract memory from register Subtract (decimal) memory from register Move (numeric) from register to memory Compare memory to register None Hint 74). If a bits D6 and D5 bits are 1 and X then port A will be in _________________ mode? Mode 1 Mode 0 Mode 2 None of the above None Hint 75). What is the standard form of IRR? Interrupt Request Register Interrupt Request Regulator Interrupt Regulator Register None of the above None Hint 8255 Microprocessor MCQ for Interviews 76). Which one of the following port works with IO mode in 8255 control word? Port A Port B Port C Both a and b None Hint 77). In which one of the following modes does port A works? Mode 0, mode 1 Mode 2 Both a and b None of the above None Hint 78). In mode 2 of 8255 the INTE 2 controlled by bit set/reset of _______________? PC4 PC6 PC2 None of the above None Hint 79). Which one of the following IO devices used in AVR based systems? Isolated IO mapped IO Memory mapped IO Both a and b None of the above None Hint 80). How many data line pins does 8255 PPI consists? Two Four Eight Sixteen None Hint 81). Which one of the following give starts of conversion pulse to the ADC? MOV AL, 98H OUT 86H, AL MOV AL, 01H None of the above None Hint 82). The 7LT4 is an example for __________________ operation? Less or equal Less than Greater or equal Greater than None Hint 83). The ‘C’ is the typical assembly language opcode of ________________ operation? Subtract memory from register Subtract (decimal) memory from register Move (numeric) from register to memory Compare memory to register None Hint 84). Which one of the following bits not used with BSR mode? D6 bit D5 bit D4 bit All of the above None Hint 85). In which one of the following the decoding is complex? IO mapped IO Memory mapped IO Both a and b None of the above None Hint 86). The 8001H is the sample address for ________________ port? Port A Port B Port C None of the above None Hint 87). Which one of the following ports used for handshaking in PB in both mode 1 and mode2 of 8255 microprocessors? PCL PCU Port A None of the above None Hint 88). Which one of the following IO devices used in Intel's hierarchy? Isolated IO mapped IO Memory mapped IO Both a and b None of the above None Hint 89). The ‘ZAP’ is the typical assembly language opcode of ________________ operation? Subtract memory from register Subtract (decimal) memory from register Move (numeric) from register to memory Zero register and add (decimal) memory to register None Hint 90). How many addresses line pins does 8255 PPI consists? Two Four Eight Sixteen None Hint 91). The ‘CP’ is the typical assembly language opcode of ________________ operation? Subtract memory from register Subtract (decimal) memory from register Move (numeric) from register to memory Compare (decimal) memory to register None Hint 92). Which one of the following port works with BSR mode only? Port B Port C Port A None of the above None Hint 93). What is the standard form of IMR? Interrupt Main Register Interrupt Mask Regulator Interrupt Mask Register None of the above None Hint 94). Which one of the following are not latched in mode 0 of 8255 microprocessor? Outputs Inputs Both a and b None of the above None Hint 95). Which one of the following comes under chip select line pins of 8255? RD pin CE pin RST pin All of the above None Hint 96). The 7LE4 is an example for __________________ operation? Less or equal Less than Greater or equal Greater than None Hint 97). Which one of the following initialize 8255, send AL to CWR? MOV AL, 98H OUT 86H, AL MOV AL, 02H None of the above None Hint 98). In which one of the following applications do we find DAC? Motor speed controls Digitally controlled gains Both a and b None of the above None Hint 99). If CS & A1 are zero, A0 is one then which one of the following ports we have to select? Port B Port A Port C None of the above None Hint 100). Which one of the following is used for HS and interrupt mode? Control Status BSR All of the above None Hint Read more about Microprocessor For More MCQs Microprocessor Question & Answers 8085 Microprocessor Question & Answers 8086 Microprocessor Question & Answers 80386 Microprocessor Question & Answers 80286 Microprocessor Question & Answers Please fill in the comment box below. Time's up
