2068 Programmer's Cartridge toolkit (Thomas B. Woods, 1986)

24K program has many built-in features (including tri-base arithmetic) and printer drivers.

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Details available here:
https://www.timexsinclair.com/product/aros-toolkit/

Instruction manual available here:
https://archive.org/details/thomas-woods/2068 Programmers Cartridge Toolkit by Tom Woods/mode/2up