59 characters, eight bytes each, for the codes $20 (space) to $5A ("Z") -- so the game can print spaces, digits, punctuation and capitals, and nothing else.

The code never names this address. It loads TEXT_FONT less $100 into the tile source instead, which is this block less $20 characters, so that a character's own ASCII code indexes it. DRAW_SUMMARY+30 and DRAW_SCORE load FONT_DIGITS for the same reason one bias further on: that is where "0" lives, so a digit's value indexes its own glyph with no adjustment at all. Drawing the two glyphs out confirms it -- FONT_DIGITS is a nought, TEXT_FONT less $100 plus $41 characters is an A, and plus $5A is a Z.