Subject: ET bitmap font files and character codes

From: Stephen G Simpson <[email-masked]>
Date: Sat, 13 Feb 93 23:24:09 -0500

Here is a better description of the ET bitmap font files and character
codes.  I extracted this information by poking around in my own copy
of ET, Version 2.00.03.  I don't know whether this information is
correct for other versions of ET.

The ET bitmap font files are as follows:

ASCFONT.15      3840   7-01-90
ASCFONT.24     12288   7-01-90
SPCFONT.15     12240   7-01-90
SPCFONT.24     29376   7-01-90
SPCFSUPP.15    10950   7-01-90
SPCFSUPP.24    26280   7-01-90
STDFONT1.15    32490   7-01-90
STDFONTS.15   360330   7-01-90
STDFONT.24    942768   7-01-90
STDFONT.24K   942768
STDFONT.24L   942768

To this list it is convenient to add:

STDFONT.15    392820

There is no actual file called STDFONT.15, but it could be created by
concatenating STDFONT1.15 followed by STDFONTS.15, and its size would
then be 32490 + 360330 = 392820 bytes.  The description below will be
given in terms of STDFONT.15 rather than STDFONT1.15 and STDFONTS.15.

The *.15 files consist of 30 byte 16x15 bitmaps, except for
ASCFONT.15, which consists of 15 byte 8x15 bitmaps.  The *.24 files
consist of 72 byte 24x24 bitmaps, except for ASCFONT.24 which consists
of 48 byte 16x24 bitmaps.  The bits within a bitmap are always in row
major order, i.e. the first row followed by the second row followed by
..., and from left to right within each row.

STDFONT.24, STDFONT.24K and STDFONT.24L are identical except that they
contain Chinese character bitmaps in Ming, Kai, and Li styles
respectively.  The description below will be given in terms of
STDFONT.24 but it applies equally to STDFONT.24K and STDFONT.24L.

A 1-byte code consists of one byte.  The possible values of the byte
are 00 through FF, i.e. 256 possibilities.  Codes 00 through FF are
used for the 256 bitmaps in ASCFONT.15 (= 256 * 15 = 3840 bytes) and in
ASCFONT.24 (= 256 * 48 = 12288 bytes).  These 256 bitmaps consist of
the IBM PC "extended ASCII" character set.

A 2-byte code consists of two bytes.  The possible values of the first
byte are A1 through FE, i.e. 94 possibilities.  The possible values of
the second byte are 40 through 7E and A1 through FE, i.e. 63 + 94 =
157 possibilities.

Codes A140 through A3BF (2 * 157 + 94 = 408 codes) are used for the
408 bitmaps in SPCFONT.15 (= 408 * 30 = 12240 bytes) and in SPCFONT.24
(= 408 * 72 = 29376 bytes).  These 408 bitmaps include punctuation
marks, graphics characters, special symbols, Roman numerals, Arabic
numerals, the Roman and Greek alphabets, and the Bopomofo syllabary.

Codes A3C0 through A3FE (63 codes) are unused.

Codes A440 through C67E (34 * 157 + 63 = 5401 codes) are used for the
first 5401 bitmaps in STDFONT.15 (= 5401 * 30 = 162030 bytes) and in
STDFONT.24 (= 5401 * 72 = 388872 bytes).  See footnote below.  These
5401 bitmaps consist of the 5401 Big-5 "frequent use" Chinese
characters.

Codes C6A1 through C8D3 (94 + 157 + 114 = 365 codes) are used for the
365 bitmaps in SPCFSUPP.15 (= 365 * 30 = 10950 bytes) and in
SPCFSUPP.24 (= 365 * 72 = 26280 bytes).  These 365 bitmaps include
some additional numerals and special symbols, the Japanese Hiragana
and Katakana syllabaries, and the Russian alphabet.

Codes C8D4 through C8FE (43 codes) are unused.

Codes C940 through F97E (49 * 157 = 7693 codes) are used for the
remaining 7693 bitmaps in STDFONT.15 (= 7693 * 30 = 230790 bytes) and
in STDFONT.24 (= 7693 * 72 = 553896 bytes).  See footnote below.
These 7693 bitmaps consist of the 7652 Big-5 "less frequent use"
Chinese characters, followed by 7 additional Chinese characters and 41
additional graphics characters.

Codes FA40 through FEFE (785 codes) are unused.

Footnote:  The size of STDFONT.15 is (5401 + 7693) * 30 = 162030 +
230790 = 392820 bytes.  The size of STDFONT.24 is (5401 + 7693) * 72 =
388872 + 553896 = 942768 bytes.

Stephen G. Simpson
Department of Mathematics, Pennsylvania State University
333 McAllister Building, University Park, State College, PA 16802
Office phone: +1 814 863-0775      Internet: [email-masked]
Home phone: +1 814 238-2274        Bitnet: T20@PSUVM
FAX: +1 814 865-3735

February 13, 1993