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Note that MAXX3 is the software package for the FEC200E tester. It is very similar to the MAXX software described below. If you are running MAXX3 read \MAXX below as \MAXX3. MAXX3 is compiled by G4TH instead of FEC4th. We will soon post a separate document describing MAXX3 in more detail.

MAXX is a software package for FEC 200 diode testers. It runs under FreeDOS, a copy of which is supplied.The package includes the program "MAXX" and associated utilities.

MAXX has two major functions, OPERATOR INTERFACE and TESTER CONTROL. These functions are time shared, so programming may be done online.


This function is used to write, edit, save and load programs and join them to the multiplex stations for controlling the tester.

Data-logging can be viewed on the screen, sent to the printer or to disk files or to all three.

Readings saved to files can then be used by various utilities, which can produce reports for SPC or other purposes.

Diagnostic routines are available also to monitor, calibrate, or troubleshoot the tester hardware. Some diagnostics run continuously in the background and others are called when needed by the operator or technician.

Online help is available to assist the operator, with lists of commands and tests, programming hints, etc.

The screen normally displays information regarding the current setup of the tester. The operator may request various reports to be displayed on the screen, printed, or saved to disk files.

Password security is supported that can restrict the changing of test programs either temporarily in memory or on disk to those persons with the appropriate passwords.


MAXX controls the tester hardware in real time. That is, it has direct control via a high-speed parallel interface of all the hardware modules that make up the tester. In addition to interpreting and performing tests in the user's programs and sorting diodes into "BIN," several other functions are supported.

Readings produced may be saved to disk files and/or printed and/or displayed in a window on the screen.

Several SELFTEST routines are performed between tests to increase confidence in the performance of the hardware.

Counts are maintained of parts tested, bin counts, etc.

Several logical input and output lines are supported to control and receive data from external devices or other testers.


The software delivered with an FEC tester is pre-installed on the hard disk and on the tape drive. No installation is required. However, you can set some user preferences or adapt the program for hardware or powerline frequency differences. This is done by editing the test file CUSTOM.TXT,which is located in the directory \MAXX.

From \MAXX you can edit CUSTOM.TXT with the command EDIT CUSTOM.TXT. EDIT is the editor supplied with FreeDOS.

CUSTOM.TXT is read each time the program MAXX is started. The changes you make will not take effect until the next time you start MAXX.


From time to time software updates will be supplied. This will be delivered on one or more diskettes. Insert Disk 1 in drive A: and enter A:UPDATE, then follow the instructions on the screen.


When starting up a new tester, please follow the instructions in the tester manual for preparation of the hardware.

Normally MAXX is started automatically by commands in the AUTOEXEC.BAT file. If you quit MAXX, you can restart it from the \MAXX directory by entering MAXX\.


MAXX runs on an IBM-compatible computer running FreeDOS. Obviously you can use this computer to run other software. However, if you consider running TSR programs or any task switching programs with MAXX, please be aware of the following:

When MAXX is performing a series of tests on a diode, it is controlling the power supplies, relays, etc. in real time. It is very important that MAXX is not interrupted for more that a few microseconds. We sometimes disable the interrupts altogether for a short time to avoid even a brief interruption. For this reason, we recommend that MAXX should have complete control of your computer and not share time with any other programs. However many programs can be run from within MAXX as described below.


You can use FreeDOS commands or even other programs from within MAXX by using our DOS command. This will suspend testing while the external command is performed.


MAXX and its supporting files and related utilities are located on drive C: in \MAXX. Within \MAXX there are several subdirectories.

Features are added to MAXX from time to time that require new files to be added. It is possible that new subdirectories may be added also. For this reason, the files and subdirectories mentioned below do not represent an exhaustive list.


Some users may be interested to know that MAXX was written in FORTH. The version of FORTH that we use is called FEC4TH. FEC4TH is our own INTERPRETER/COMPILER. It is nearly but not completely compliant with ANSI FORTH 94. FEC4TH is included with our software distributions.

This source language is completely invisible to the user. We mention it because we also supply source files for MAXX (although not necessarily for all included utilities).

You will see files with the extension .TXT and .EXT in \MAXX or its subdirectories. These are source or startup files.

The .TXT and .EXT files can be read and edited with FreeDOS's EDIT command. For example: EDIT TESTER.TXT

Although you can edit these files, we hope you will not do so. A better course is to call us with your suggestions for improvements or additions.

We frequently make changes as the result of suggestions from our customers and we welcome the opportunity to do so.


As a general rule, we don't recommend modifying MAXX. There may be some circumstances where it is called for. For example, if you need a change and you need it NOW, usually we can get you a modified version tomorrow or the next day, or even today by sending a software patch by email.

Here is how to recompile MAXX after making a minor change to the source code (more about that later).

From the \MAXX subdirectory, while in FreeDOS, enter FEC4TH (for MAXX3 use G4TH).

The FORTH interpreter will open up and you will see its opening banner.


Watch for error messages as MAXX recompiles. There will be a number of informational messages but hopefully no errors. When the process is complete, you will be asked to "press any key." The new MAXX.EXE will now be written.


Typically you will be entering changes that we have communicated by phone or FAX.

There are two types of source files, .TXT and .EXT.

Both types can be edited with the EDIT command in FreeDOS, example: EDIT TESTER.TXT


.EXT are read each time MAXX starts, or when needed, so if you change them the changes take effect next time you use MAXX.


It is a very good idea to have a copy of the latest update handy "just in case." You could also make backup copies of any files that you will modify as well as a backup of MAXX.EXE.

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Last Updated September 12, 2007
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