Trap 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 TRAP pin equivalently as RST 4.5. It is referred as trap by INTEL. Non-maskable interrupt is TRAP whereas maskable is interrupt. At location 4.5 * 8, we do not have the ISS. As an example, in the ALS kit we have instruction JMP 0182H in the 3 bytes starting at 4.5 * 8 = 0024H.


Published on 12-Mar-2019 17:20:20