Apple PC Serial and Parallel Card - Manual (Page 29)

Opening the computer
1 Shut down the computer and disconnect all cables from the computer, except for the
power cord.
Leave the computer plugged in for now, to ground it and protect its
components from static electricity damage.
2 If the security bar is installed, remove it by removing the screw under the front panel and
pressing the center of the bar.
Note: The computer in the illustration is a Power Macintosh 7300. Not all
computers come with or can accept a security bar. If your computer did not
come with a security bar, skip this step.
First remove the screw.
Then press the security bar near
its center to release it from the computer.
29 Installing the Card in a Power Macintosh 7200, 7300, 7500, or 7600