Salvaging microcontrollers for electronics projects.

There is a lot of microcontrollers in junk electronic equipment that can be used and reapplied to homebrew electronic projects. The key is to know what to look for and knowing what types of microcontrollers are useable once salvaged. Older microcontrollers from Intel and Motorola, and their numerous clones almost always had external access, or mode control pins that allowed you to force the microcontroller to run off of an external program ROM. So, no mater if they have a window in the top of the chip for UV erasing, or not, they can be used “AS IS”. Examples are 804*, 874*, 8019*, and 68*** series microcontrollers. Newer microcontrollers on the other hand, unless they are the reprogrammable type with flash ROM, then they are pretty much a paperweight if you do take the time to salvage them. And there lies the primary problem with most newer microcontrollers used in mass produced equipment. They are usually the OTP (One Time Programmable), and not the reprogrammable type. Once in a while you will find a flash microcontroller on some low end product in the field, but more often than not, it will be a OTP chip. So, when salvaging newer microcontrollers, you have to make sure and check the part number to see if you will even be able to use it once you do remove it from the junk circuit board. Example of those is the newer PIC, and Amtel microcontrollers. Some are OTP and some are Flash. Happy hardware hunting.