Second episode in a new series of videos looking at programming in 6502 assembly code! In this second video, I examine how custom characters and user defined graphics work on an Acorn 8-bit machine, in order to demonstrate how you can use 6502 assembly to print custom characters - and even fill the screen with them in more than double the speed of a higher level language like BASIC!

My aim with this series is to explore how 6502 assembly programming works, and compare programs written in BBC BASIC to their equivalent in 6502. This is a "learn as you go" series, as I am very much a beginner myself. The intention here is for you to learn along with me, as I make use of the BBC BASIC in-line assembler to drop into and out of assembly code, demonstrating how it works and how it compares to higher level languages like BASIC.

Special thanks, as always, to Chris Bradburne for both the inspiration behind this video series and for his help in collaborating with me on it.

Extra special thanks to Nicole Marie T for providing "Creative Assembler", a specially commissioned piece of backing music used in this series. You can hear more of Nicole's work here: https://nicolemakesmusic.wixsite.com/nicolemariet

Piconet thread on Stardot (JimR & Ken Lowe's creation): https://stardot.org.uk/forums/viewtopic.php?t=26775

00:00 Intro

00:53 PicoNet adapter

01:30 VDU 23

04:12 What those VDU numbers mean

07:28 Bitmaps

09:02 Calling OSWRCH

11:37 A simple lookup table

12:27 Building the bitmap loop

13:12 Decrement, not increment

16:15 BASIC vs. 6502

19:43 Outro