The early TRS-80s had a system of character graphics for displaying rather chunky-looking graphics on the screen. These characters split the possible character display area up into a 2x3 grid (don't know the pixel size of a character, but this suggests it was something like 6x9) and all the combinations were available.

Some of these systems accomplished this by using a mutant 7-bit form of ASCII with only 64 of the normal characters and 64 of these special graphic characters; they didn't have lower case letters. (Later systems had a full 8-bit ASCII including lower case characters and these same graphics, starting with the Model III. High-resolution graphics was a separate capability that came later.)

The first systems had a display of 64x16 characters, for a full screen graphics resolution (with these 2x3 symbols) of 128x48. Later ones had an 80x24 display, which allowed a graphics resolution of 160x72. This was the system I played Pillbox on.

All monochrome of course. Tandy computers didn't get color until the CoCo years later.

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