A Low-Cost Development System For M6805 Microprocessors

48 EE January 1989 A LOW-COST DEVELOPMENT SYSTEM FOR M6805 MICROPROCESSORS by Peter Topping Development systems for single-chip MCUs can be complex and expensive, dissuading potential users of this type of microproces- sor from designing them into new applications. This article describes a low-cost `entry" development system for debugging hardware and software for Motorola"s M6805 range of microprocessors. The M6805 range includes both CMOS and NMOS parts, all but one of which are single-chip devices which include mask-programmable ROM, RAM, I/O and a timer function. The exception is the CMOS MC146805E2, which has no on-chip ROM but has a multiplexed data/address bus that enables it to use external memories and peripherals. The development system described uses the MC146805E2 processor, and can be used to develop applications intended for the MC146805G2, MC146805F2, or the E2 itself. It can also be used for ap- plications intended for NMOS variants such as the MC6805P, U and R fam...