patch-1.3.1 linux/drivers/char/README.unicode

• Lines: 50
• Date: Tue Jun 13 10:47:47 1995
• Orig file: v1.3.0/linux/drivers/char/README.unicode
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.0/linux/drivers/char/README.unicode linux/drivers/char/README.unicode
@@ -0,0 +1,49 @@
+The Linux kernel code has been rewritten to use Unicode to map
+characters to fonts.  By downloading a single Unicode-to-font table,
+both the eight-bit character sets and UTF-8 mode are changed to use
+the font as indicated.
+
+This changes the semantics of the eight-bit character tables subtly.
+The four character tables are now:
+
+Map symbol	Map name			Escape code (G0)
+
+LAT1_MAP	Latin-1 (ISO 8859-1)		ESC ( B
+GRAF_MAP	DEC VT100 pseudographics	ESC ( 0
+IBMPC_MAP	IBM code page 437		ESC ( U
+USER_MAP	User defined			ESC ( K
+
+In particular, ESC ( U is no longer "straight to font", since the font
+might be completely different than the IBM character set.  This
+permits for example the use of block graphics even with a Latin-1 font
+loaded.
+
+In accordance with the Unicode standard/ISO 10646 the range U+F000 to
+U+F8FF has been reserved for OS-wide allocation (the Unicode Standard
+refers to this as a "Corporate Zone").  U+F000 was picked as the
+starting point since it lets the direct-mapping area start on a large
+power of two (in case 1024- or 2048-character fonts ever become
+necessary).  This leaves U+E000 to U+EFFF as End User Zone.
+
+The Unicodes in the range U+F000 to U+F1FF have been hard-coded to map
+directly to the loaded font, bypassing the translation table.  The
+user-defined map now defaults to U+F000 to U+F1FF, emulating the
+previous behaviour.
+
+In addition, the following characters not present in Unicode 1.1.4 (at
+least, I have not found them!) have been defined; these are used by
+the DEC VT graphics map:
+
+U+F800 DEC VT GRAPHICS HORIZONTAL LINE SCAN 1
+U+F801 DEC VT GRAPHICS HORIZONTAL LINE SCAN 3
+U+F803 DEC VT GRAPHICS HORIZONTAL LINE SCAN 7
+U+F804 DEC VT GRAPHICS HORIZONTAL LINE SCAN 9
+
+The DEC VT220 uses a 6x10 character matrix, and these characters form
+a smooth progression in the DEC VT graphics character set.  I have
+omitted the scan 5 line, since it is also used as a block-graphics
+character, and hence has been coded as U+2500 FORMS LIGHT HORIZONTAL.
+However, I left U+F802 blank should the need arise.  
+
+	H. Peter Anvin <Peter.Anvin@linux.org>
+	Yggdrasil Computing, Inc.