Modeling Intel 8085A in VHDL

In this paper we present a model of completely functional Intel 8085A processor in VHDL, starting from scratch. The majority of the work is based on the specification for 8085A, with some changes that are considered better for the implementation. All of the processor building blocks are modeled and integrated. An interface to the memory and I/O address space is also provided. Since each instruction is distinguished by a unique operational code, the final product is a processor capable of successfully executing an assembler program which is loaded in memory as a sequence of operational codes.