From 86b772d57253b9019102eace0cc442f5f7cb37b2 Mon Sep 17 00:00:00 2001 From: Michaelangel007 Date: Mon, 11 Jan 2016 14:21:16 -0800 Subject: [PATCH] Fix spelling, and added 7x8 cell calc --- README.md | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/README.md b/README.md index 8c7377b..a13445b 100644 --- a/README.md +++ b/README.md @@ -238,7 +238,13 @@ Here's the [Javascript source code](list_hgr_table.html) to generate this table: ### No FONT data in ROM -Second, each glyph in the Apple font is in a 7x8 cell -- the leading line on the bottom is usually blank but we'll store that too so that we have a true "underline" and bottom descender on 'j', 'y', etc. +Second, each glyph in the Apple font is in a 7x8 cell -- the leading line on the bottom is usually blank but we'll store that too so that we have a true "underline" and bottom descender on 'j', 'y', etc. How do we know this? + +The `TEXT` screen is 40x24 characters. The high resolution graphics `HGR` screen is 280x192. + + Char Width (px/character) = Screen Width (px) / Columns (characters) = 280/40 = 7 + + Char Height (px/character) = Screen Height (px) / Rows (characters) = 192/24 = 8 Unfortunately, the data for the TEXT ROM 25123 hardware chip is **not** accessible from the 6502. :-/ This means you will need to manually enter in the 8 bytes/character. :-( The good news is that I've already done this so you can copy / paste. :-) @@ -328,7 +334,7 @@ Enter in: ![Screenshot 5](pics/hgrfont_05.png?raw=true) -We actually _also_ need to move the right-edge pixel of these 2 scanlins over left by 1 pixel so it appears in the correct location when shifted: +We actually _also_ need to move the right-edge pixel of these 2 scanlines over left by 1 pixel so it appears in the correct location when shifted: 2304:22 2704:92 ;