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8085 Articles
Page 23 of 36
RST5.5 and RST6.5 pins in 8085
Both the pins RST5.5 and RST6.5 pins are inputs which are level sensitive. RST6.5 is of higher priority than RST5.5 but the pin RST5.5 is of higher priority than INTR. RST5.5 and RST6.5 have similar functions. The point to be noted that these pins must remain high till the 8085 checks all the internal interrupt signals at the end of the instructions. As we can easily see from the Fig. We activate the RST5.5 and RST6.5 internal interrupt signals if and only if when the external interrupt pins are in logic 1 state;Flip-flop IE is in logic 1 state;SIM instructions ...
Read MoreRST7.5 pin in 8085
RST7.5 pin is an input which is edge-sensitive. Peripherals uses it for sending a pulse, rather than a sustained high level, for the interruption of the processor. Internal to 8085 we have a flip-flop which gets connected to the interrupt pin RST7.5. We set this flip-flop to 1, when a positive-going edge occurs on the input RST 7.5. The waveform of pin RST7.5 and output Q of RST7.5 flip-flop is shown in the Fig.Internal interrupt signal RST7.5 has a priority higher than the internal interrupt signals of RST6.5, RST5.5 and INTR. As we can see from fig the RST7.5 internal interrupt ...
Read MoreI/O-mapped I/O or memory-mapped I/O in 8085 Microprocessor
Before having a discussion regarding the demerits or merits of I/O mapped I/O and memory-mapped I/O, let us have a generic discussion regarding the difference between I/O mapped I/O and memory mapped I/O.In Memory Mapped Input Output −We allocate a memory address to an Input-Output device.Any instructions related to memory can be accessed by this Input-Output device.The Input-Output device data are also given to the Arithmetic Logical Unit.Input-Output Mapped Input Output −We give an Input-Output address to an Input-Output deviceOnly IN and OUT instructions are accessed by such devices.The ALU operations are not directly applicable to such Input-Output data.So as ...
Read MoreTrap interrupt pin in 8085
A non-maskable interrupt is a Trap Interrupt which implies that whenever this pin gets activated, the 8085 always gets interrupted even if the state of 8085 is in DI. The input of Trap input is level sensitive and edge sensitive. Hence the Trap line always makes a transition from 0 to 1, and remains in state 1 until the end of the execution of an instruction for the interruption of 8085. A vectored-interrupt in 8085 is a TRAP. The starting address of 8085 is known by itself the of the ISS as 4.5 * 8 = 0024H. Hence we name the ...
Read MoreNeed for masking in 8085
Let us say that the 8085 which is interrupted because of RST6.5 pin and has been branched to the ISS for the pin RST6.5. Then, except the DI instruction at the beginning of this ISS, all the interrupts gets disabled except TRAP. So, even if RST7.5 pin is in activated state in the middle of the execution of RST6.5 ISS, the interruption of 8085 will not occur due to RST7.5. Actually a higher priority interrupt is RST7.5, but the lower priority interrupt ISS cannot be interrupted by it of RST6.5. We solve this problem by specifically having the instruction which ...
Read MoreProgram for simulation of throwing a die in 8085 Microprocessor
Write an 8085 assembly language program to simulate the throw of a die using an interrupt.We have a counter for this program, which counts the ranges from 1 to 6, and again repeats the sequence of count in a matter which is endless in an infinite loop. The die throwing getting the head and tail probability gets simulated by pressing the key ‘Vect Intr’ on the keyboard. The branching of 8085 branches to RST7.5 ISS. Here, the current value of the counter gets is displayed in the data field, which controls and returns to the main program for the continuation ...
Read MoreProgram for simulating a stopwatch in 8085 Microprocessor
We write an 8085 assembly language program just to simulate a stopwatch for displaying minutes and seconds in the address field. There exists a provision to stop the stopwatch, along with the display for continuation to show the time just previous to the stop command.FILE NAME STOPWACH.ASM PRESSING THE ‘VECT INTR’ KEY STOPS THE STOPWATCH, WITH STATIONARY DISPLAY ORG C000H CURAD: EQU FFF7H UPDAD: EQU 06BCH RESET: LXI H, 0000H REPEAT: SHLD CURAD CALL UPDAD; Display time present in HL in the address field MVI A, 00011011B SIM ; Unmask RST7.5, Reset RST7.5 flip flop EI ; Enable interrupt ...
Read MoreProgram for adding 2 numbers input from keyboard in 8085 Microprocessor
We write an 8085 assembly language program of two input using two 2-digit hexadecimal numbers from the keyboard and then we add and the output results in the address field.FILE NAME ADD2NUM.ASM ORG C000H CURAD: EQU FFF7H UPDAD: EQU 06BCH CLEAR: EQU 044AH GTHEX: EQU 052FH MVI A, 0EH SIM EI ; Unmask RST5.5 and enable interrupts MVI B, 01 CALL GTHEX ; Input a 2 digit number and display in data field MOV A, E STA C100H ; Store the 2-digit hex number in C100H MVI B, 01 CALL GTHEX ; Input a 2 digit number and display in ...
Read MoreProgram for adding 4 hex digits of a 16-bit number in 8085 Microprocessor
We write an 8085 assembly language program for the addition of 4 hex digits of a 16-bit number whose input is given from the keyboard and the result is displayed in the data field.FILE NAME ADDHEX.ASM ORG C000H CURDT: EQU FFF9H UPDDT: EQU 06D3H GTHEX: EQU 052FH HXDSP: EQU 05A1H OBUFF: EQU FFFAH MVI A, 0EH SIM EI ; Unmask RST5.5 and enable interrupts MVI B, 00 CALL GTHEX ; Input a 4 digit number and display in address field CALL HXDSP ; Store the 4 hex digits in 4 locations starting from OBUFF LXI H, OBUUF MOV A, M ...
Read MoreInterfacing 7(Seven) Segment Display to 8085 Microprocessor
An output device which is very common is, especially in the kit of 8085 microprocessor and it is the Light Emitting Diode consisting of seven segments. Moreover, we have eight segments in a LED display consisting of 7 segments which includes ‘.’, consisting of character 8 and having a decimal point just next to it. We denote the segments as ‘a, b, c, d, e, f, g, and dp’ where dp signifies ‘.’ which is the decimal point. Moreover, these are LEDs or together a series of Light Emitting Diodes. We have shown the internal circuit comprising of a display ...
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