From 505b2707138ecd125d7e00a2bdc949fcf8f2b74f Mon Sep 17 00:00:00 2001 From: michaelangel007 Date: Sun, 10 Jan 2016 18:47:18 -0800 Subject: [PATCH] Fix up TOC DrawChar() --- README.md | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/README.md b/README.md index d7ad624..3ad3893 100644 --- a/README.md +++ b/README.md @@ -1,6 +1,6 @@ #Apple ]\[ HGR Font Tutorial -Revision: 14, Jan 10, 2016. +Revision: 15, Jan 10, 2016. # Table of Contents @@ -15,8 +15,9 @@ Revision: 14, Jan 10, 2016. * Font Data * Raw Font Data * Image to Font Data (Javascript) -* Font -> Screen Memory Trace -* DrawChar version 1 +* DrawChar() + * Font -> Screen Memory Trace + * DrawChar() version 1 * X Cursor Position * CursorCol() * DrawChar() version 2 @@ -38,7 +39,7 @@ Revision: 14, Jan 10, 2016. * Misc. Utilities and Files * TODO -## Introduction +# Introduction A lot of people in comp.sys.apple2.programmer and other places on the internet have wondered how to "print" text onto the Apple's High Resolution Graphics (HGR) screen. Here's a tutorial on "6502 Font Blitting." @@ -58,7 +59,7 @@ If you use: There are other emulators written in Javascript but they are poor due to 2 reasons: -* Don't support paste -- you'll be forced to manually enter in the hex code. :-/ +* Don't support paste -- you'll be forced to manually enter in the hex code. :-/ Yeah, right! * Don't emulate the half-pixel shift of real hardware at all. @@ -240,7 +241,7 @@ Here's the [Javascript source code](list_hgr_table.html) to generate this table: 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. -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. :-) +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. :-) You can find a picture of the Apple ][ ROM text font on Page 8-9, diagram 8.4 of "Understanding the Apple ]\[" https://archive.org/stream/understanding_the_apple_ii#page/n203/mode/2up @@ -577,6 +578,8 @@ Note: If you get a retarded `Uncaught SecurityError: Failed to execute 'getImage Another solution is to use a web browser that isn't "broken" such as Firefox, etc. when trying to read _local_ files. +# DrawChar() + ## Font -> Screen Memory Trace OK, so now that we have the font data, how do we draw a character "on screen" ?