01․ Maximum of how many devices can be connected simultaneously to the microprocessor via 8257 in DMA data transfer mode?
Maximum 4 devices can be connected simultaneously to the microprocessor via 8257 in DMA data transfer mode.
02․ A microprocessor with a 12-bit address bus will be able to access
A microprocessor with a 12-bit address bus will be able to access 212 =22 × 210 = 4 K bytes
03․ The frequency of the driving network connected between pins 1 and 2 of 8085 microprocessor is
In 8085 microprocessor the input 1 and 2 determines the clock frequency. It is generally a RC or LC type network.Two such network when working parallel gives half of their respective frequency as equivalent frequency.So the driving network connected between pin 1 and 2 must have twice of the desired frequency.
04․ A high on RESET OUT signifies that
A high on RESET OUT signifies that all the registers and counters are being reset and this signal can be used to reset external support chip.
05․ How can we make any bit of a register “0”?
If we want to make any bit “0”, then we have to AND that bit with “0” so that the bit becomes “0”. We also have to AND the remaining bits of the register with “1” so that they remain unaltered.
06․ PSW stands for
PSW (Processor Status Word) is a combined status of accumulator and flag register together where accumulator is the higher-order register and the flags are the low-order register.
07․ DMA is used between
DMA (Direct memory access) is a process of high speed data transfer under the control of external devices.It is used when the microprocessor controlled data transfer is too slow. DMA allows data transfer between source and destination thus bypassing the microprocessor. DMA is used between memory and I/O.
08․ Temporary registers in 8085 are
W and Z are temporary registers which are used only by processor. These registers are used to hold 8 bit data during the execution of some instruction. They are not accessible to the users.
09․ Register pair used to indicate memory
In microprocessor BC,DE and HL register pair can be used by the programmer.H and L register pair is used to act as memory pointer and it holds 16 bit address of memory location.
10․ Total numbers of output pins in 8085 microprocessor are
Total no. of output pins in 8085 is 27. The output pins are A8-A15(8pins), AD0-AD7(8 pins),ALE,S0,S1,IO/M, RD,WR,HLDA,INTA,RESET OUT,CLK,SOD.