FONT% = P% DIV 256 INCBIN "1-source-files/fonts/P.FONT.bin"Name: FONT% [Show more] Type: Variable Category: Text Summary: A copy of the character definition bitmap table from the MOS ROMContext: See this variable in context in the source code Variations: See code variations for this variable in the different versions References: This variable is used as follows: * CHPR calls FONT%
This is used by the TT26 routine to save time looking up the character bitmaps from the ROM. Note that FONT% contains just the high byte (i.e. the page number) of the address of this table, rather than the full address. The contents of the P.FONT.bin file included here are taken straight from the following three pages in the BBC Micro OS 1.20 ROM: ASCII 32-63 are defined in &C000-&C0FF (page 0) ASCII 64-95 are defined in &C100-&C1FF (page 1) ASCII 96-126 are defined in &C200-&C2F0 (page 2) The code could look these values up each time (as the cassette version does), but it's quicker to use a lookup table, at the expense of three pages of memory.