From b454ca191d55a51da8b0a68cc1d33cfef31ddd52 Mon Sep 17 00:00:00 2001
From: Rikard Nordgren <hrn@posteo.net>
Date: Mon, 26 Jan 2026 19:21:17 +0100
Subject: [PATCH] Update mov_r_FAC1_TMP1

---
 STATUS.md                                 |  2 +-
 src/basic/math_mov/bbca.mov_r_FAC1_TMP1.s | 19 +++++++++++++++++--
 src/basic/math_mov/mov_r_FAC1_TMP1.s      | 18 ------------------
 tools/similarity.c                        |  2 +-
 4 files changed, 19 insertions(+), 22 deletions(-)
 delete mode 100644 src/basic/math_mov/mov_r_FAC1_TMP1.s

diff --git a/STATUS.md b/STATUS.md
index 99c892ad..3fe31c2a 100644
--- a/STATUS.md
+++ b/STATUS.md
@@ -224,7 +224,7 @@ Floating point mathematical routines - not official, but well known and broadly
 | `$BBA2`   | `mov_MEM_FAC1`         | DONE     |                                                    |
 | `$BBA6`   | `get_FAC1_via_INDEX`   | DONE     |                                                    |
 | `$BBC7`   | `mov_r_FAC1_TMP2`      | PARTIAL  | not fully tested yet                               |
-| `$BBCA`   | `mov_r_FAC1_TMP1`      | PARTIAL  | not fully tested yet                               |
+| `$BBCA`   | `mov_r_FAC1_TMP1`      | DONE     | From the Microsoft BASIC, original name: MOV1F     |
 | `$BBD0`   | `mov_r_FAC1_VAR`       | DONE     | From the Microsoft BASIC, original name: MOVVF     |
 | `$BBD4`   | `mov_r_FAC1_MEM`       | DONE     | From the Microsoft BASIC, original name: MOVMF     |
 | `$BBFC`   | `mov_FAC2_FAC1`        | DONE     | From the Microsoft BASIC, original name: MOVFA     |
diff --git a/src/basic/math_mov/bbca.mov_r_FAC1_TMP1.s b/src/basic/math_mov/bbca.mov_r_FAC1_TMP1.s
index 51494056..057a230e 100644
--- a/src/basic/math_mov/bbca.mov_r_FAC1_TMP1.s
+++ b/src/basic/math_mov/bbca.mov_r_FAC1_TMP1.s
@@ -3,6 +3,21 @@
 ;; #LAYOUT# *   BASIC_0 #TAKE
 ;; #LAYOUT# *   *       #IGNORE
 
-; Just a compatibility jump - our routine is longer than original one
+; This file is under the MIT license, it contains code released by Microsoft Corporation.
+; See LICENSE for more information.
 
-	jmp mov_r_FAC1_TMP1
+; Math package - store FAC1 (rounds) in TEMPF1
+;
+; This is verified to be identical to the original Microsoft implementation where it was named MOV1F.
+;
+; See also:
+; - https://www.c64-wiki.com/wiki/BASIC-ROM
+; - https://sta.c64.org/cbm64basconv.html
+;
+
+mov_r_FAC1_TMP1:
+
+    ldx #TEMPF1
+    ldy #0
+
+    beq mov_r_FAC1_MEM      ; Always branches
diff --git a/src/basic/math_mov/mov_r_FAC1_TMP1.s b/src/basic/math_mov/mov_r_FAC1_TMP1.s
deleted file mode 100644
index 79917784..00000000
--- a/src/basic/math_mov/mov_r_FAC1_TMP1.s
+++ /dev/null
@@ -1,18 +0,0 @@
-;; #LAYOUT# STD *       #TAKE
-;; #LAYOUT# *   BASIC_0 #TAKE
-;; #LAYOUT# *   *       #IGNORE
-
-;
-; Math package - store FAC1 (rounds) in TEMPF1
-;
-; See also:
-; - https://www.c64-wiki.com/wiki/BASIC-ROM
-; - https://sta.c64.org/cbm64basconv.html
-;
-
-mov_r_FAC1_TMP1:
-
-	ldy #$00
-	ldx #$5C
-
-	jmp mov_r_FAC1_MEM
diff --git a/tools/similarity.c b/tools/similarity.c
index 2108dd72..09c09389 100644
--- a/tools/similarity.c
+++ b/tools/similarity.c
@@ -24,7 +24,7 @@ int phase_mask[MAX_SIZE+MAX_SIZE];
 // Pairs of start, end memory addresses of known exact similarity with the open source Microsoft BASIC
 unsigned short microsoft_basic_chunks[NUM_CHUNKS * 2] = {
     0xB849, 0xB84F,
-    0xBBD0, 0xBC1A
+    0xBBCA, 0xBC1A
 };