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If you press RCL # # during a call, the air time of the call flashes on the display until you clear the display or end the call.

Note: To set your phone so it displays the individual call timer automatically, see “Turning the Automatic Call Timer On/Off” on Page 27.

Using the Resettable Call Timer

The resettable call timer tracks the calls you make or answer in minutes, and it can be reset at any time. You can reset this timer to coincide with your cellular billing statement date, for example, then track your monthly air time.

To display the resettable call timer, press RCL #

#

# . The phone displays Resetbl and the number of air time minutes (such as 00215) accumulated since you last reset the timer. Press any key to clear the timer from the dis- play.

To reset the timer, with the display clear, press FCN OPER 0

PRS 7 CLR .

Displaying the Cumulative Call Timer

The cumulative call timer tracks all the calls you make or an- swer in minutes. It cannot be reset.

To display the cumulative call timer, press RCL , #

#

#

# . The phone displays Cumul and the number of

air time minutes (such as 00846) accumulated since the first call was made or answered on your phone. Press any key to clear the timer from the display.

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Radio Shack CT-502 owner manual Using the Resettable Call Timer, Displaying the Cumulative Call Timer
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CT-502 specifications

The Radio Shack CT-502 is a remarkable device that stands out in the world of vintage technology, particularly known for its versatility and functionality as a portable computer. Launched during a time when personal computing was rapidly evolving, the CT-502 embodies the spirit of innovation that characterized the early days of computing technology.

At its core, the Radio Shack CT-502 comes equipped with a Zilog Z80 microprocessor, a staple of many early personal computers that provided solid performance for its time. This CPU offers an 8-bit architecture with a clock speed of 2.5 MHz, allowing users to execute tasks efficiently. The CT-502 features a memory capacity of 64 KB of RAM, which can be expanded, making it suitable for various applications, from basic text processing to simple programming tasks.

One of the standout features of the CT-502 is its dual built-in floppy disk drives, which enable users to easily load and save data. This was particularly advantageous during the era when storage solutions were evolving, as it allowed for quick access to programs and files. The 5.25-inch floppy disks used by the CT-502 became a standard for many personal computing applications, ensuring wide compatibility with software.

The device also features a compact, built-in keyboard that boasts a full set of function keys, essential for efficient data entry and navigation. Complementing the keyboard is a 40-character by 24-line monochrome display, which provides a clear view of text and applications, ideal for programming and document creation.

In terms of connectivity, the CT-502 includes a variety of ports such as serial and parallel interfaces, allowing users to connect external devices like printers and modems. This functionality enhanced the versatility of the system and integrated it into the growing network of computers.

Moreover, the Radio Shack CT-502 runs on the TRS-DOS operating system, designed specifically for the TRS line of computers. This operating system was user-friendly for its time, enabling users to manage files and perform various tasks without deep technical knowledge.

In summary, the Radio Shack CT-502 represents a significant milestone in early computing history, offering a combination of portability, ease of use, and expansion capabilities. With its reliable hardware, user-friendly interface, and diverse connectivity options, it remains a fondly remembered piece of technology that paved the way for modern personal computers.
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