One field of the EgaSavePtrRec points to an EgaTxtFontRec.  Initially,
this structure does not exist, but it may be installed by DOS national
language support or other TSR code.

EgaTxtFontRec
Offset Size Contents
                                                                          
+0      1  bLenOneChar  size, in bytes, of one character definition
+1      1  bRamBank     character generator RAM bank
+2      2  wCharCnt     number of characters defined
+4      2  wFirstChar   ASCII code of first character defined
+6      4  pfabDefTbl   far address of the Font Definition Data table.
The table is a set of wCharCnt bitmaps, each
containing bLenOneChar bytes (usually 8 or 14).
See INT 1FH for related info.
+0aH     1  bAplcblRows  applies when video mode has this many text lines
+0bH     n  abModes      use for these video modes (variable-length table)
+n+0bH   1  ffH          ffH indicates end of abModes table
n+0cH              size of an EgaTxtFontRec

On VGA systems, a second 256-character font may be setup by initializing
the EgaSavePtrRec.pfSavePtr2 to a VgaSavePtr2Rec and setting its
pfTxtAuxFont field to point to another EgaTxtFontRec structure.  This
secondary character set would be activated according to the mode values
in the abModes field.

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EgaTxtFontRec