From 6754725c9b4b31369549fe7af9de1a58087521a3 Mon Sep 17 00:00:00 2001 From: n loewen Date: Tue, 15 Aug 2023 15:28:42 +0100 Subject: [PATCH] Docs: Add dev notes for 2023-08-15 --- notes/2023-08-15--dev-notes.md | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) create mode 100644 notes/2023-08-15--dev-notes.md diff --git a/notes/2023-08-15--dev-notes.md b/notes/2023-08-15--dev-notes.md new file mode 100644 index 0000000..29533c4 --- /dev/null +++ b/notes/2023-08-15--dev-notes.md @@ -0,0 +1,22 @@ +# Dev notes — 2023-08-15 + +## Goals for today + +- [x] Review planned changes to simulator + - [x] 'opcodes' and 'operands' + - [x] fix $00 contains $20 bug + +- [ ] Review planned changes to the system + - [x] CHP, CFC -> FHP, FTG -- dev note 2023-08-07 + - [ ] ? 5x5 display + - [ ] bank-switching flag in 0 page + +- [ ] Implement any changes necessary for writing a program? +- [ ] Write a program + - [ ] LOGO turtle on 5x5? + +## Overflow flag + +Ken Shirriff, [The 6502 overflow flag explained mathematically](https://www.righto.com/2012/12/the-6502-overflow-flag-explained.html): + +> A common definition of overflow is `V = C6 xor C7`. That is, overflow happens if the carry into bit 7 is different from the carry out. \ No newline at end of file