Fixing a Bug in Rodnay Zaks' "Programming the 6502"

Rodnay Zaks' "Programming the 6502" is a classic, but it's also got a bug! We take a deep look at the Block Transfer Routine on pages 204-208, find the bug, and then demonstrate and (nearly, see notes below) fix it in Turbo Macro Pro on the C64. Programming the 6502: https://archive.org/details/Programming_the_6502 UPDATE! The source in file BLKCPY8 (shown in the video) has a bug, discovered by RETRO Innovations. BLKCPY9 (included in the .d64 linked below) has the fix suggested by csbruce. Also on the .d64, viewer jjeeeekk came up with a faster-running fix which is file BLKCPY11 on the .d64, and also checkout elandje's version which is BLKCPY10. Block Transfer .d64: https://8BitShowAndTell.com/prg/tmpzaks.d64 Become a patron: https://patreon.com/8BitShowAndTell One-time donation: https://paypal.me/8BitShowAndTell Ending credits is an unreleased song by Bedford Level Experiment, lyrics by Robin's son. Check out other songs here: https://bedfordlevelexperiment.bandcamp.com/ Index: 0:00 Z80, 6502, and Rodnay Zaks 1:07 Programming the 6502 editions 2:40 A Block Transfer Routine p. 204 4:50 Reading time! 7:46 Looking at the printed source code 14:46 The kind of clever bit - which is the bug! 17:07 Indexed indirect? 23:14 FINALLY THE C64! 24:19 Loading Turbo Macro Pro 27:33 Running the program 30:14 Demonstrating the bug 32:15 Some cleanup 34:35 A fix (of a fix)! 38:08 A couple tests 40:30 Thanks to my patrons