Texas Instruments TMS370 - Manual (Page 27)

Properly Installing the Programmer Hardware
1-13
To install a PLCC device:
With this release of the programmers, the PLCC sockets do not have a lid;
therefore, they are not sensitive to the device package height. These new
sockets also have the pin 1 orientation at the top of each socket, making it less
likely for you to insert a device backwards.
1) Place the PLCC in the empty socket.
2) Press firmly until it is properly seated.
The programmer hardware is now ready to use.
To remove the device, press down firmly on the black plastic socket edges until
the device is pushed upward and released.