diff --git a/c64/aliases/,aliases_cpu.s b/c64/aliases/,aliases_cpu.s
index 85f94c76..922a91bc 100644
--- a/c64/aliases/,aliases_cpu.s
+++ b/c64/aliases/,aliases_cpu.s
@@ -111,6 +111,21 @@
 
 
 
+//
+// Calculation shortcuts
+//
+
+.pseudocommand lda_zero                // WARNING: do not use within interrupts
+{
+#if HAS_OPCODES_65C02
+	tba
+#else
+	lda #$00
+#endif	
+}
+
+
+
 //
 // Stack manipulation - some CPUs will leave .A unchanged, some will use it as temporary storage, so consider .A trashed
 //
diff --git a/c64/basic/math/MOVFM.s b/c64/basic/math/MOVFM.s
index f0dbb066..9f6c510c 100644
--- a/c64/basic/math/MOVFM.s
+++ b/c64/basic/math/MOVFM.s
@@ -71,13 +71,10 @@ MOVMF:
 	lda (INDEX), y
 	sta FAC1_exponent
 
-	// Set low order mantissa - to my surprise original ROM seems to put 0 to FACOW - XXX why???
-	// Since we do not know the original value (lost due to variable format having one byte shorter
-    // mantissa than FAC1), it is probably best to put some approximate value here; putting $80
-    // would be risky in case rouding is performed later, $7F seems to be sane choice
+	// Set low order mantissa to 0 - this should give the
+	// most precision while operating on integers
 
-	lda #$7F
-	sta FACOV
+	sty FACOV
 
 	// Return the FAC1 exponent
 
diff --git a/doc/Development.md b/doc/Development.md
index 427a037b..86c3160d 100644
--- a/doc/Development.md
+++ b/doc/Development.md
@@ -88,7 +88,7 @@ List of the most important make targets:
 Currently there are 2 ROM layouts defined:
 
 - `STD` - with 2 code segments: `BASIC` (`$A000-$E4D2`, where `$C000-$DFFF` is a skip-gap for RAM and I/O area) and `KERNAL` (`$E4D3 - $FFFF`)
-- `M65` - where `BASIC` becames `BASIC_0` and `KERNAL` becames `KERNAL_0`, additional segments might be added to the build system in the future; at the moment of writing this document additional 8KB of ROM is defined as `KERNAL_1` segment
+- `M65` - where `BASIC` becames `BASIC_0` and `KERNAL` becames `KERNAL_0`, additional segments might be added to the build system in the future; at the moment of writing this document additional 8KB of ROM is defined as `BASIC_1` segment and additional 8KB of ROM is defined as `KERNAL_1` segment
 
 To check for current ROM layout or code segment use KickAssembler preprocessor defines, like `ROM_LAYOUT_STD`, `ROM_LAYOUT_M65`, `SEGMENT_BASIC`, `SEGMENT_KERNAL_1`.