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In this lab we will be programming a GAL, which encapsulates the ADL into a single chip.

  1. Fill out the GAL work sheet to represent your ADL design. Place a diagonal line accross junctions where fuse is out and place a circle around junctions where fuse remains.

  2. The next step is to create the *.jed file that allows you to burn a GAL. This is done by modifying the file emp21.jed so that it reflects the logic you designed in your worksheet. In this case, the / and 0 from the worksheet should correspond to 1s and 0s in your new *.jed file.

NOTE: show a copy of your gal.jed to your AI's BEFORE you run GALTOPAL.exe. The TA will check your file before you burn it.

  1. Burn both GALs. If it is wrong, it's electronically erasable. If it's right, it will save you lots of time when you need a gal for the vector board computer.

  2. After you have successfully programmed the GAL, wire it up to the switches and lights so that you can test it. Inform a lab instructor that you are ready to test your GAL chip and they will help you -- this is VERY IMPORTANT. Our experience over the years is that more often than not the GAL contains errors. Sometimes a GAL with errors will appear to work even though the ADDRESS DECODE LOGIC rules are not followed. Such a computer may work intermittently -- this can be a major problem later. Print and save a copy of the .JED file. The GAL worksheet, .JED file, pinout, and functional diagram must be included in your final report.

  3. Test the GAL by replacing all of your logic and running the VIA test program. If the computer does not function properly, go back and redo the MPU, RAM and IRQ tests in order. This should help you localise the problem.