Recently, being interested in Debian-derived Linux distributions, I came
across a reference to "12-dot" kanji fonts.
Googling gave one hit (dated 1999) that mentioned 12 x 12 fonts, and even
10 by 11 fonts. While I might have seen these at some point, I'm frankly
quite surprised that such crude arrays of dots could work. Seemingly by
coincidence, I had, only a few days before, seen a specimen of laser
dot-matrix marking that apparently used a 12-dot font; it was difficult to
tell the size of the matrix. The specimen looked as if it were created by
the ink-jet printers for corrugated cartons, which produce legible
markings, but are pretty awful, typographically.

Apparently, the standard set of roughly 2,200 kanji in Japan has enough
uniqueness for each character to avoid ambiguity. (Does it, really?)
Whether the 12-dot fonts cover all of the standard set, I have some
doubts, but the possibility gives me new respect. It has seemed to me for
some time that the design of CJK strives to avoid ambiguity (as should any
good writing system).

I've forgotten whether some kind soul confirmed it, but 24-pin printers
seem to have been designed with that number of pins (which defines the
height of the array) to render standard kanji acceptably; that seems to be
the minimum required.

=====

More generally, around 1950 I was quite interested in the topic of
determining the smallest matrix of dots which would render
esthetically-acceptable text; I didn't pursue the matter very far,
although I have been looking at dot-matrix fonts with more than passing
interest. Although 4x7 can be useful, 5x7 is standard for cap. letters
only (ASCII only -- no diacritics!) For small-letter descenders, 5x9 works
well.

An historical note is that around 1964 or so, or perhaps 1970, Motorola
(and probably other companies) made IC chips with fonts built in; their
data book had some quite-interesting exact repersentations of the built-in
fonts. Some matrices were fairly large, perhaps 10x14, but that's an
unreliable guess. One is reminded of the choices provided in a Win 9x "DOS
Box".

The small fonts provided in MS Windows machines can go down to a 2 x3
matrix, I think; not sure. Context is needed to resolve ambiguity, I'd
assume.

Our computers still render text in rectangular arrays of dots, but the
count can become quite large, e.g. for headline text. It seems that a good
working figure for modern CRT monitors is about 90 dots per inch.

=====

Finally, there's no need to mention 7-segment fonts, but there's a
Japanese variation that has segments with peculiar shapes instead of
simple rectangles (or thin parallelograms). It's been used in some
handheld calculators, primarily (if not exclusively) for numerals. At one
time there was a seven-segment numerical impact printer (with a ribbon)
that, instead of tiny pins, pressed the ribbon with the ends of stiff
metal strips in the familiar pattern. I'm also reminded of an electronic
typewriter (Casio?) that actually wrote out the text by moving and lifting
a tiny ball pen. It was not connected script; text looked conventional.

However, less well-known is a 14-segment layout, usually referred to as
"starburst" that (iirc) permits entering both caps and small letters, as
well as a good repertoire of punctuation. Ugly as sin, it does work. It's
oblique, as are the 7-segment fonts, and it pattern is like a large + sign
superimposed onto a capital X, all that inside a parallelogram box. There
are separate commas and decimal points; they aren't included in the count
of 14.

Regards,

--
Nicholas Bodley /*|*\ Waltham, Mass.
The curious hermit -- autodidact and polymath
Total lie -- saying that SocialSecurity is in crisis:
<http://www.truthout.org/docs_05/011805I.shtml>