Not totally sure what I'd use this for. Silkscreen is bigger, but is a lot more legible at small sizes.
At first this was when writing SCSI disk drivers for a third party Mac disk maker. Later it was when writing network drivers for a company making a SCSI ethernet interface. Then it was when working on firmware for some NuBUS cards for Mac II.
I didn't want to write a full BITBLT, but I didn't want to make width + spacing be 8 pixels because even though that would be very easy it would also mean I could only have 64 characters to a line on the Mac or Mac Plus (512 x 342 display).
With characters 3 pixels wide and 1 space between them you just need a simple BITBLT that only has to handle two cases.
My font was 3x5. Unlike the other 3x5 fonts people have mentioned I didn't try to include lower case. Here's a sample, scaled up by factor of 4:
The reason that there is a prominent visible symbol for newline is because when the debug print got to the bottom of the screen it would wrap back to the top. The prominent newline let you tell which characters on the line came from the latest print on that line.
A font with a higher resolution, ie more pixels or finer coordinates for a vector based one, has a chance to be more readable at smaller physical sizes.
> Not totally sure what I'd use this for.
It's mostly just for fun and artistic expression. The linked article mentions the font being used for some album covers.
For that, if you wanted to see what was going on, a quick copy and paste of the text into a regular editor will show you the characters at a reasonable size.