From da0d5dc2a5c186e24ec3abeb9816bdb0d3747ec3 Mon Sep 17 00:00:00 2001 From: Paul Gardner-Stephen Date: Wed, 24 Apr 2019 09:55:29 +0930 Subject: [PATCH] add explanations of matching strings --- strings/8D0DDC | 4 ++++ strings/8D0DDD | 4 ++++ strings/A9118D | 5 +++++ strings/A9818D0DDC | 3 +++ strings/AD0DDD | 4 ++++ strings/F0036C | 11 +++++++++++ 6 files changed, 31 insertions(+) create mode 100644 strings/8D0DDC create mode 100644 strings/8D0DDD create mode 100644 strings/A9118D create mode 100644 strings/A9818D0DDC create mode 100644 strings/AD0DDD create mode 100644 strings/F0036C diff --git a/strings/8D0DDC b/strings/8D0DDC new file mode 100644 index 00000000..c1ea5695 --- /dev/null +++ b/strings/8D0DDC @@ -0,0 +1,4 @@ +Store to $DC0D + +This single instruction stores to $DC0D. +This cannot be copyrighted. diff --git a/strings/8D0DDD b/strings/8D0DDD new file mode 100644 index 00000000..d559feed --- /dev/null +++ b/strings/8D0DDD @@ -0,0 +1,4 @@ +Store to $DD0D + +This single instruction stores to $DD0D. +This cannot be copyrighted. diff --git a/strings/A9118D b/strings/A9118D new file mode 100644 index 00000000..80009782 --- /dev/null +++ b/strings/A9118D @@ -0,0 +1,5 @@ +Store value $11 somewhere in memory +LDA #$11 +STA $xxxx + +This is the obvious way to put $11 into a memory location, and thus not copyrightable. diff --git a/strings/A9818D0DDC b/strings/A9818D0DDC new file mode 100644 index 00000000..ff940f8a --- /dev/null +++ b/strings/A9818D0DDC @@ -0,0 +1,3 @@ +Enable CIA1 TimerA interrupt minimal instruction sequence +LDA #$81 +STA $DC0D diff --git a/strings/AD0DDD b/strings/AD0DDD new file mode 100644 index 00000000..f1dfad55 --- /dev/null +++ b/strings/AD0DDD @@ -0,0 +1,4 @@ +Read from $DD0D + +This single instruction reads the value stored in $DD0D. +This cannot be copyrighted. diff --git a/strings/F0036C b/strings/F0036C new file mode 100644 index 00000000..e7706e6f --- /dev/null +++ b/strings/F0036C @@ -0,0 +1,11 @@ +Branch over following JMP ($nnnn) instruction +A branch with argument $03 skips the following 3 bytes. +A JSR instruction has the initial byte value of $20. +Therefore $F0 $XX $20 is part of a +Bxx + +JMP ($xxxx) +* + +instruction sequence. +This is a very common construction, and the logical way to +conditionally call a routine via a vector, and therefore is not copyrightable.