This article is from the Apple II Csa2 FAQ, by Jeff Hurlburt with numerous contributions by others.
By: Steve Jensen Here's info from my files on the 'shift key mod': The one wire shiftkey mod is the oldest and simplest fix that can be made to the Apple II to get true upper and lower case operations with the shift key. Most good word processors have input routines that check the PB2 input on the game I/O port to determine if the shift key is being pressed. Some programs that have these routines are Wordstar, Write-on, Apple Pascal 1.1 and many others. Follow the steps below to install the shift key mod. parts: 1 mini-grabbette clip (Radio Shack PN 270-370) 1 15 in. piece of small guage wire 1 16 pin socket 1) Solder one end of the wire to the mini-grabbette clip. 2) Solder the other end of the wire to pin 4 of the 16 pin socket as close to the body of the socket as possible. 3) Turn the Apple II off and remove the cover. 4) Remove anything plugged into the game I/O socket. 5) Attach the mini-grabbette clip to pin 24 of the keyboard encoder connector. This connector is located inside the Apple II directly beneath the RESET key. Pin 1 is nearest the power supply and pin 25 is nearest the right edge of the Apple II. Use the grabbette clip to attach to the standoff pin 24 (second from the end). 6) Lead the other end of the wire with socket attached along the right edge of the motherboard and plug it into the game I/O port. Be careful to plug pin 1 to pin 1 when putting this socket in. Pin 1 of the game I/O port is towards the front of the computer. 7) Replace the cover and start using lower case characters.