I have found cracking procedure for the following chips:
16c54,16c55,16c56,16c57,16c58,16c61,16c62,16c64,16c65,16c71,16c73,16c74,16c84The procedure supposedly gives you some bits of the instruction word and you are left to select one of two possible instructions by context. Also, the procedures seem to be generic and should work on all 12bit and 14bit chips.
The [older versions of the] Pic chip (PIC16C84) can in fact have it's program and data memory read after the config fuses have been set to code protection on. Try the following:
- Write some code to the chip with the code protection set to "ON".
- Read back to verify that the protection has indeed come on.
- Now set Vdd ( pin 14 ) to Vpp-0.5v, (Programming voltage less 0.5V).
- Set config fuse to "OFF" and reprogram config fuse. Ignore error messages.
- Now set Vdd back to normal, +5v.
- Power off the programmer.
- Wait 10 to 20 sec to allow the charge on the cells to fall back to 5 volts.
- Power back on the programmer. (VDD at + 5V)
- Read the Pic....
and hey presto, data in unprotected format should now be available.