mnicmp

Stewart C. Russell - scruss.com 2017-02

a 7-pin dot matrix font based on the DECwriter II output, with some international characters added from the DECwriter III character set, and then some additional ones created by me.

Name

Digital Equipment Corporation (DEC) used to make minicomputers. The older ones of these only supported 6.2 file names, so the word ‘minicomputer’ would have to be rendered as ‘mnicmp’.

Few of them supported lower-case, so let's just skip that detail.

Coverage

Most of ISO-8859-15, but not all of it. The DECwriter II only supported a subset of ASCII, and the DECwriter III added a very few European characters

Design Size

If printed at 12 pt with no additional line spacing, you should match the DECwriter's 10 cpi horizontally and 6 lpi vertically.

Variants

While the DECwriter only had one type style, I added more:

Italic — this is done by shearing the array of points and replacing them with circular dots. Using a regular italicize function produces ugly oval dots.
Bold — this mimics double-striking, with the second character offset ½ of the dot width. It looks better than it should.
Bold Italic — skewed and double-struck.
Light and Light Italic — lightened the font by making the circles smaller. As none of the dots overlap, this might make a decent stencil font.

Noticing that the dots could be arbitrary shapes, I got a bit carried away:

Diamond-shaped dots - the matrix is made of rounded diamonds instead of circles. Also provided in italic.
Square dots — very blocky indeed. Also provided in italic.
Star-shaped dots — exceedingly silly and twinkly. Would have been a great way to punch holes in paper on a real dot matrix printer. Also provided in italic.

And then there's LoveMatrix, which uses the same dot matrix layout but with tiny hearts ...

Source

Source to all fonts is included in FontForge format. The small Python program used to create the fonts from JSON data is also included. You may create your own new variants/characters provided that that you do not use the reserved name ‘mnicmp’.

If you wish to make you own characters, the JSON structure is a hash/dictionary of dot bitmap arrays against unicode character:

 chars = {
          ...
          'A':  ['...#...',
                 '..#.#..',
                 '.#...#.',
                 '#.....#',
                 '#.#.#.#',
                 '#.....#',
                 '#.....#'],
          ...
         }

Everything that's a # counts as a dot; everything else is ignored. Character order doesn't matter.

If you wish to preserve the original DECwriter look, remember that it couldn't have two adjacent horizontal pixels struck across a 7 pixel character. So the most pixels you can have struck across is character is 4 out of 7.

Licence

This Font Software is licensed under the SIL Open Font Licence, Version 1.1. This licence is included, and is also available with a FAQ at: http://scripts.sil.org/OFL

[I do not agree with SIL's missionary work in any way, and the use of this licence is in no way an endorsement of SIL.]

Reference

ASCII char matrics — LA36 DECwriter II Maintenance Manual, pub. Digital Equipment Corporation - Maynard, MA; First Edition, June 1975. Copyright © 1975 by Digital Equipment Corporation, part no EK-LA36-MM-001. URL: http://www.textfiles.com/bitsavers/pdf/dec/terminal/la36/EK-LA36-MM-001_LA36_DECwriter_II_Maintenance_Manual_Jul75.pdf. See Table 1-1 Standard ASCII Character Set and Code (p.1-2 - folio 15) - page image
Intl char matrices, print sizes — LA120 Technical Manual, Digital Equipment Corporation - Maynard, MA; First Edition, January 1980. Copyright © 1980 by Digital Equipment Corporation, part no EK-LA120-TM-001. URL: ftp://bitsavers.informatik.uni-stuttgart.de/www.computer.museum.uq.edu.au/pdf/EK-LA120-TM-001%20LA120%20Technical%20Manual.pdf. See Table 3-3 Code Differences Among National Character Sets (p.3-7 - folio 51)

A note on underlining, overstriking and bold

If in doubt, don't. The DECwriter supported none of these. It had 7 vertical pin positions and no descenders. Its underline row was the baseline of all characters. Its minus character was at roughly x-height, so is not useful for overstriking. To illustrate this, here are the pin maps of -, m and _:

       .......          .......          .......  
       .......          .......          .......  
       .......          #.#.#..          .......  
       #.#.#.#          #..#..#          .......  
       .......          #..#..#          .......  
       .......          #..#..#          .......  
       .......          #..#..#          #.#.#.#

Note that there are no pin positions below the baseline. The fonts all include the standard algorithmic outline underbar/underline at 100 units below the standard baseline (200 units) in a 1000 unit em. It looks nothing like anything the DECwriter could do. You can't not have an underline position in a font, so it had to go somewhere

Other cuts by other people

Sevenpins is also based on DECwriter matrices, but with different spacing.

scruss / mnicmp