All 320 Characters

Normally the TRS-80 Model 3 can only display 256 of its 320 characters at any one time. The first 192 are always the same while the last 64 can be flipped between a set of Japanese characters and a hodge-podge of greek letters, math and random symbols.

By flipping between the two different sets of 64 characters at exactly the right time every frame this demo gets all 320 characters on screen at once. Just look at this screen shot (well, I took out the blank lines at the bottom).

It's way harder than you might think to get everything to happen at just the right time. Also demonstrated is the hardware's ability to switch character sets without getting weird about it. You never know what can happen when a program fiddles with display registers in an unusual way.

The demo has no interactive component. Examine the characters until you've had enough.

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George Phillips, August 12, 2009. george -at- 48k.ca