The Radio Shack Lower Case Kit
Lower case kit from a 1980 Radio Shack catalog
Introduced in late 1979 at around the same time as the Scripsit word processor, the price for the Radio Shack Lower Case Kit started out at $99.99 (plus installation) but was soon lowered to $59.95. Despite the use of the name “kit,” Radio Shack required installation by a Radio Shack technician.
The Radio Shack kit included an updated character generator to improve the look of the lower case characters. It also used a slightly different approach than the Electric Pencil modification. Instead of requiring a switch to enable and disable lowercase, lowercase was enabled all the time. This created the potential for conflicts but there were only a handful of incompatible programs, most notably two from Radio Shack: Level II Cassette Payroll and Accounts Receivable. Radio Shack provided updated versions of those programs to affected customers free of charge.
Even though the Radio Shack kit allowed lower case characters to be displayed on screen, the Model I ROM provided no consistent way to type them using the keyboard. Some programs, such as Scripsit, contained their own keyboard driver, but using lower case in Level II BASIC required a separate lower case driver. The kit came with a lower case driver on tape that loaded into high memory and enhanced the ROM keyboard driver to support lower case. Pressing SHIFT+0 toggled the upper/lower case state (there was no shifted 0 character on the TRS‑80 keyboard). This key combination to switch case became the TRS‑80 standard. Eventually, most Model I disk operating systems automatically installed their own lower case drivers without requiring a separate driver.
The TRS‑80 Model III, introduced not much later in August 1980, offered lower case as a standard feature. It had a lower case keyboard driver in ROM that toggled case with SHIFT+0, just like the Model I kit. Due to new FCC rules, Radio Shack discontinued the Model I in the United States on January 1, 1981. However, Radio Shack continued to sell the Model I overseas until at least 1982. As part of a video circuit revision in late 1981, the hardware of the Radio Shack Lower Case Kit was folded into the Model I motherboard. Although Radio Shack never publicized the fact, this meant that the final Model I’s sold required only a standard driver to enable lowercase.