The TRS‑80 Model 4P
In October 1981, Alpha Products created a new version of their joystick which included a mode switch to allow a choice between the STICK-80 and TRISSTICK FIRE button behavior. The advertisements from then on referred to the joystick as the Alpha Joystick, and the price remained at $39.95.
Radio Shack introduced the eventual replacement to the Model I, the Model III, in 1980 (the Model II, introduced in 1979, was part of a separate line of business computers). Unlike the Model I, the Model III was an all-in-one design; the monitor, keyboard, and disk drives were all in the same unit. This cut down on radio interference and helped with school sales (which were concerned with students walking away with computer components in their bags). Like the Model I, the Model III used a Z-80, but running at 2.0 MHz this time. The Model III was largely, but not completely, software and hardware compatible with the Model I. It featured a more powerful 14K Level II BASIC ROM, lowercase support, and had a numeric keypad built right in. It had sockets to support up to 48K RAM internally, two internal drive bays, and with an optional floppy disk controller, operated in double-density by default.