diff --git a/apple2/diskette16sector.go b/apple2/diskette16sector.go
index 7f6ded2..391057a 100644
--- a/apple2/diskette16sector.go
+++ b/apple2/diskette16sector.go
@@ -172,15 +172,15 @@ func nibEncodeTrack(data []byte, volume byte, track byte) []byte {
 		b = append(b, 0xd5, 0xaa, 0xad) // Data prolog
 		prevV := byte(0)
 		for _, v := range secondaryBuffer {
-			b = append(b, sixAndTwoTranslateTable[v|prevV])
+			b = append(b, sixAndTwoTranslateTable[v^prevV])
 			prevV = v
 		}
 		for _, v := range primaryBuffer {
-			b = append(b, sixAndTwoTranslateTable[v|prevV])
+			b = append(b, sixAndTwoTranslateTable[v^prevV])
 			prevV = v
 		}
-		b = append(b, prevV)            // Checksum
-		b = append(b, 0xd5, 0xaa, 0xeb) // Data epilog
+		b = append(b, sixAndTwoTranslateTable[prevV]) // Checksum
+		b = append(b, 0xde, 0xaa, 0xeb)               // Data epilog
 	}
 
 	return b
diff --git a/main.go b/main.go
index e1054be..ef14b68 100644
--- a/main.go
+++ b/main.go
@@ -7,7 +7,7 @@ func main() {
 	romFile := "apple2/romdumps/Apple2_Plus.rom"
 	//romFile := "apple2/romdumps/Apple2e.rom"
 	disk2RomFile := "apple2/romdumps/DISK2.rom"
-	diskImage := "../dos33.nib"
+	diskImage := "../dos33.dsk"
 
 	log := false
 	a := apple2.NewApple2(romFile)