The PicoMite built in font #8, or alternatively the Pico-8 font are, I’m guessing, the tiniest semi-legible font that could be used on the PicoCalc. With those, you can get 80 columns wide by 53-ish rows tall on the screen. But that’s very tiny and would probably be painful to read.
The 5x8 font for zeptoforth (also at that link above) which I adapted for PicoCalc lets you do 64 columns wide by 40 rows tall on the PicoCalc screen and is a bit more legible, but I’m still not sure it would allow for comfortable reading of a lot of material. Larger fonts like the default editor font are easier to read, and would give extra space for the possibility of adding styling if using it as a template for a new font(s) (see below).
The other thing to consider with PicoMite fonts is there’s no concept of bold, italics, underline, subscript, superscript, etc. And there’s only a limited number of symbols. That’s generally fine for most programs, and would be ok for a “notepad” like text viewer. But if you want to have something more like an ebook reader, that missing functionality might be needed, or at least useful. Implementing it would complicate things.
Two possible routes (though I’m sure there are others) would be:
- Create a custom font, or potentially several custom fonts (since I’m not sure one could contain all the characters), and embed the bold/italics/underline/etc. effects in the font characters. Then you could still use text mode (or optionally graphics mode) to display the fonts. I’m not sure if you can mix fonts when using them in text mode though, so that may be a problem, and it might still require graphics mode if you can’t easily mix and match in text mode.
- Instead of actually making the font effects look like they should, use the graphics mode “scale” parameter to, say, increase the size of bolded text, or shrink the size of italics text. Alternatively, use different colors to denote the different styles. Or use some combination of the two. Scale would also allow you to have headings and things that need to be larger, but it would complicate things since you’d need to manage the (x,y) location of every bit of text and ensure that nothing spills into anything else or writes over the top of anything else. That would be a lot of tracking calculations, and scrolling the page would need to be taken into account too, unless paging was enforced.
My guess is that trying to stuff all the effects into a font, or fonts, might be the best option because then you ignore scaling altogether (and all the position management it would entail). Might still require rendering in graphics mode, but keeping everything the same size, with embedded styling and optional color coding would probably be enough to make it a better reading experience. Still wouldn’t be close to an ePub reader, but it might be a decent compromise. Easiest thing might be to use color coding for all styling, and not bother modifying the font at all and just have a “help screen” available somewhere.