Applied Microsystems EM-188  
Written by Accutron on 2017-03-18  

The Applied Microsystems EM-188 is an in-circuit diagnostic emulator for Intel 8080 and 8085 systems. The EM-188 can emulate either the 8080A/8080A-1/8080A-2 or 8085A/8085A-2 microprocessors, requiring two separate emulator probes to support both devices. The most basic function of the EM-188 is to emulate the target system's microprocessor, while a 251x32 bit trace memory captures information from each bus cycle. The trace memory records 16 address bits, 8 data bits, CPU read/write cycles, and the type of bus signal.

The information captured by the trace memory allows the user to examine or alter the microprocessor's register contents, memory locations and I/O ports, and automatically generate breakpoints based on specified conditions. The EM-188 has two independent address comparators which constantly monitor the target microprocessor's address bus. Each comparator may be set to generate a breakpoint on read and/or write cycles, as well as memory and I/O addresses. The comparators can also be configured interactively to generate a breakpoint based on sequential conditions or a range of address values. Additionally, the EM-188 has a large selection of preprogrammed diagnostic routines.

Applied Microsystems manufactured a number of similar emulator products for different microprocessors. EM-184 and EM-180 emulate the Zilog Z80, EM-186 emulates the Motorola 6800, EM-189 emulates the Motorola 6809, and EM-149 emulates the MCS-48 family of microcontrollers. The first of these systems was the EM-184, designed by Applied Microsystems founder Robin Knoke in 1979. Later EM-1xx models, derived directly from the EM-184 platform, were designed by engineer Tim Nelson in the early 1980s.

Special thanks to Victor Rizzardi for donating this system.

Applied Microsystems EM-188 Diagnostic Emulator User's Manual (PDF)
Applied Microsystems U.S. Price List 04/1983 (PDF)


Applied Microsystems EM-188 Diagnostic Emulator.


EM-188, internal construction. The EM-188 console is built almost entirely from 74LS00 series TTL and various types of RAM. The readout is constructed from six Texas Instruments TIL311 intelligent LED displays.


EM-188 8085 emulator probe, internal construction. The secret to perfect in-circuit emulation of an 8085 is to use an actual 8085.

This article is part of the [Digital Computers] exhibit.

©2000-2017 The Vintage Technology Association. All rights reserved.