The easiest way to tell the difference between a backlit and non-backlit Portable is, of course, to see if there is a light emanating from the display.
Another way to tell is to check the model number, located on the bottom of the unit. The Backlit Portable was model number M5126 and the non-backlit was M5120.
Note: If the non-backlit model had an upgrade to the backlit, it would retain the old model number, M5120 and have the backlight upgrade card installed in the J10 ROM slot and have inprinted on it "PORTABLE BACKLIGHT UPGRADE".
Article Change History:
26 Apr 1995 - Added more info on how to differentiate between models.
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