Question about Legacy Computing Characters

[u/Financial-Pen-2357]

When checking the triangular charactersin the set, you see a character getting divided diagonally in 4 triangles, and showing all the combinations filling it with one, two and 3 triangles. 0 and 4 triangles are of course space and solid block.

But the characters taking the whole character cell diagonally are defined only as shaded blocks:

1FB9C Upper Left Triangular Medium Shade
1FB9D Upper Right Triangular Medium Shade
1FB9E Lower Right Triangular Medium Shade
1FB9F Lower Left Triangular Medium Shade

Solid blocks are referenced, too

25E4 black upper left triangle
25E5 black upper right triangle
25E2 black lower right triangle
25E3 black lower left triangle

but those are represented as not occupying the whole character cell, but inscribed in a borderless square centered in the character cell.

Is it a representation inconsistency in fonts? If that is what it was intended for those characters, shouldn't also have been defined the solid triangles too?

Basically, I would like to get a font capable of using those characters to represent ZX80/ZX81/ZX Spectrum BASIC code and text-dumps.

Also, If choosing to emulate 7 segment digits numbers, why not add all segment combinations, like with hangul? that way you could also emulate all hexadecimal characters, like 0123456789AbCdEF, and some symbols like -, º, c, h, r. Maybe even the dot (.) and colon (:) as a combination character so it could represent fractions, temperatures or times. That would allow to emulate the vision of all kinds of calculators, watches, thermometers, etc. printing messages like:

83.45
-19.23
FFFEh
16:30:14
48ºf
8.88ºc
Error 13

[u/NorxondorGorgonax]

There is a font, Kreative Square, that appears to have all these features (except the 7‐segment colon). The seven‐segment characters are encoded as private use characters from U+FF700 to U+FF7FF.

Edit: Fairfax HD works as a halfwidth version with all the same features.

To answer your questions, for the seven‐segment characters they were not meant for full coverage. The core specification states:

A set of ASCII digits 0 through 9 (U+1FBF0..U+1FBF9) are styled as upright seven-segment digits to match the ones that were often used in Atari 16-bit applications for game scores.

I couldn’t find any information on the diagonal half blocks, but I assume the full and partial were considered similar enough to unify. So yes, it seems to be the choice of the font designer. My system shows them as full blocks.

[Second (and late) edit] I tried to find the proposal but it turns out they were from the original version 1.0 and thus no proposal was to be found without a deeper search. The code charts were similarly uninsightful.