z80 » Beginner
The TI86 has a screen of 128 by 64 pixels. That makes room for 8 rows of 21 large characters. The operating system it runs is called TI-OS. TI bumped it up the processor to run at about 4.8 MHz.
Because everyone makes mistakes, TI has tried to fix theirs by putting out several changes to their internal software. You can check which version you have by pressing the following keys:
[2nd] [MORE] [ALPHA] 
There are only a couple versions out there.
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Aliases // Convert from decimal to hexadecimal or binary // Flags and Conditions // Format and Compiling // Instructions // Math // Number Bases // Oh, No! It Crashed! // Registers // TI-BASIC to Asm Comparisons // TI86 Specifications // Two's Compliment // z80 Processor