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The first two Apple II models (the ][ and ][+) were unable to display lower case on the text screen. Some 3rd parties made lower-case adapters that replaced the character ROM (e.g. Dan Paymar's popular device). The device from Lazer Systems (a/k/a Lazer MicroSystems) was called the "Lower Case Plus", pictured here. One of the interesting features was that you could use an EPROM programmer to replace the font with one of your own design. You could also add on a "Character Set Plus" to have additional ROM fonts.

Lazer Systems had another product called the "Graphics Plus", which allowed the font to be updated with software. The idea was that you could use text characters as graphics tiles and create games that ran much faster than similar code that used the hi-res screen (the text screen being 1/8th the size).

How did font selection and updating work?

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They replaced the character generator ROM with a static RAM chip, and provided a path by which the CPU could read and write this RAM. A single 2K×8 chip (which became available at about that time) would have held 256 different 7×8 patterns. Fonts would have been loaded from mass storage.

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  • Do you have any of the documentation for it? I haven't been able to find any info at all beyond one-line references in old magazine ads and product catalogs. – fadden Jan 17 '17 at 5:24
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    I'm afraid not. The only reference I found online was in the "New Products" section of an old magazine. But I knew exactly what they were talking about, because I had designed much the same kind of thing myself back in the day. Not for the Apple II specifically, but for another 6502-based system from Ohio Scientific. – Dave Tweed Jan 17 '17 at 5:36

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