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Parallel Port Programmer




The Needham EMP-20 Parallel Port Programmer


Although the TOP853 programmer includes the TI 2564 (8k EPROM) in its list of supported devices, I found that my TOP853 could neither read nor write a 2564. After searching the web for other programmers that were supposed to support the 2564, I was considering upgrading to a later model TOP programmer; both the TOP3000 and TOP3100 included the 2564 in their lists of supported devices, but, given my experience with the TOP853, I was somewhat wary of spending over 100 on something that might also fail to work as advertised.

Instead, I managed to find a Needham EMP-20 on eBay. Having used one of these programmers some 20 years ago, I was confident that it would do the job. The obvious drawback with the device is that it uses a parallel port connection to the PC. Most of my PCs do not have a parallel port, but I do have a Thinkpad laptop with a parallel port in its port replicator.

The other potential issue with the EMP-20 is that the software runs under DOS only and will not run in a DOS box under the most recent versions of Windows (after Windows 7). Windows 3.1, 95 and 98 should be OK, computers running Windows XP have variable results. There is a Driver Update that should allow the programmer to work under Windows XP (or NT/2000).

My EMP-20 was missing its power supply, the Needham pages on advised that the power supply was 12-16 Volts @ 2.5 Amp, AC or DC


Product Details

Summarised from the Needham's product overview (available below)

"The EMP-20 programmer is an inexpensive, portable, parallel port programmer that was designed from the ground up to be fast and versatile. It easily connects to your PC through a standard parallel port." The EMP-20 uses plug-in "family modules" to configure the programmer for different devices." Each family module supports an entire family of devices. Three family modules are included in the base price of the programmer to support 8/16 bit EPROMS, 87xxx MICROS, and a number of PLDs.

Family Modules are not an entirely new idea. They have been use in other programmers from time to time, to inexpensively route power and ground to the device. When you're programming devices fairly slow, then straight, slide-in connectors are just fine. However, the EMP-20 programs at speeds near the theoretical maximum of some devices, so the digital signals traveling to the device must be clean, and the power and ground lines must be solid. Slide-in connectors can experience noise problems, higher resistance, and corrosion.


Running Under Windows XP

The following has been tested on a ThinkPad T61 with a Type 2504 docking station/port replicator running Windows XP SP3.

The docking station that I originally used with my T61 was a pretty simple port replicator - it did not have a parallel port.

When I bought the EMP-20, I ordered a more advanced version of the docking station from a computer recycler on eBay. Since the T61 is now well past its "sell-by-date", I managed to get a Type 2504 for 7.50 including P&P.
Driver Installation

Unzip EMPNT.ZIP (available at the bottom of the page) which will create EMPNT.EXE.

Run the program with Administrator permissions.

Select the EMP-20 programmer and the Port Base for the parallel port.

The default PC parallel port is 0x3BC, this can be checked from the parallel port properties in Device Manager.
Windows NT (and Windows XP) do not allow direct access to the parallel port from a Window.

The driver installation displays the information box opposite which describes how the run the EMP-20 programmer software in Full Screen mode.
Once the driver installation has completed, the computer needs to be rebooted.

When the EMP20 program is run, a Splash screen is displayed which confirms the version number. The latest version that I have found is Version 4.18.

NB : For presentation reasons, most of the screen captures on this page were done in Window mode - the program needs to be run Full Screen in order to access the parallel port. 
If the driver has not been installed correctly, the program is running in a window, rather than full screen or the parallel port is otherwise unavailable, the program displays this error message.   
If the parallel port is accessible, but the programmer cannot be found, the program displays this error message.
If the programmer cannot be found, the program can be run in "Demo" mode.  



When the programmer is plugged in, the Device Driver will be loaded and the system should be ready to go.



EMP20 DOS Software : Version 4.18    
EMPNT Parallel Port driver update for NT/Win2000/XP    
EMP-20 Overview (Needham's document downloaded from    
EMP-20 Device List (Needham's web page recovered from    
EMP-20 Device List (Needham's PDF file from matthieu.benoit's site)    
EMP-20 NT Device Driver (Needham's web page recovered from    
EMP-20 DOS Software Manual (    
An EMP20 clone was distributed by Electronic Engineering Tools in the mid '90s as the ProMax
ProMax User's Manual (from matthieu.benoit's site)
Current eeTools website (there are no EMP20 resources on this site)
How to makeEMP-20 work with Windows XP (Manufacturers Automation Inc.)    
EMP-20 Miscellaneous (    

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