From 79e6af86ca526d5fb56af6f6ca3da713e3a5e9f9 Mon Sep 17 00:00:00 2001 From: Thomas Voss Date: Tue, 13 Feb 2024 13:02:28 +0100 Subject: Genesis commit --- src/NOTES | 7 +++++++ 1 file changed, 7 insertions(+) create mode 100644 src/NOTES (limited to 'src/NOTES') diff --git a/src/NOTES b/src/NOTES new file mode 100644 index 0000000..d155ab1 --- /dev/null +++ b/src/NOTES @@ -0,0 +1,7 @@ +The shl and shr instructions are often documented to take both a Vx and a +Vy argument. It’s a bit unclear what the behaviour here is meant to be. +The original CHIP-8 implementation shifted Vy by 1 and stored the result +in Vx. Some GitHub projects shift the value in Vx by the value in Vy. +Ahoy takes the approach of SCHIP where Vx is shifted by 1 and Vy is +ignored. The Ahoy assembler does not recognize a second Vy argument to +either instruction. -- cgit v1.2.3