diff -Naur owfs-2.9p0/module/owlib/src/c/ow_1921.c owfs-2.9p0-6/module/owlib/src/c/ow_1921.c
--- owfs-2.9p0/module/owlib/src/c/ow_1921.c	2012-12-15 15:28:40.000000000 +0100
+++ owfs-2.9p0-6/module/owlib/src/c/ow_1921.c	2013-05-02 13:27:40.522908400 +0200
@@ -98,6 +98,7 @@
 WRITE_FUNCTION(FS_w_controlrbit);
 READ_FUNCTION(FS_r_statusbit);
 WRITE_FUNCTION(FS_w_statusbit);
+WRITE_FUNCTION(FS_clrmem);
 
 /* ------- Structures ----------- */
 #define HISTOGRAM_DATA_ELEMENTS 63
@@ -174,7 +175,7 @@
 
 	{"mission", PROPERTY_LENGTH_SUBDIR, NON_AGGREGATE, ft_subdir, fc_subdir, NO_READ_FUNCTION, NO_WRITE_FUNCTION, VISIBLE, NO_FILETYPE_DATA, },
 	{"mission/enable", PROPERTY_LENGTH_YESNO, NON_AGGREGATE, ft_yesno, fc_link, FS_r_controlrbit, FS_w_controlrbit, VISIBLE, {u:_MASK_DS1921_MISSION_ENABLE}, },
-	{"mission/clear", PROPERTY_LENGTH_YESNO, NON_AGGREGATE, ft_yesno, fc_link, FS_r_controlbit, FS_w_controlbit, INVISIBLE, {u:_MASK_DS1921_CLEAR_MEMORY}, },
+	{"mission/clear", PROPERTY_LENGTH_YESNO, NON_AGGREGATE, ft_yesno, fc_link, NO_READ_FUNCTION, FS_clrmem, VISIBLE, {u:_MASK_DS1921_CLEAR_MEMORY}, },
 	{"mission/running", PROPERTY_LENGTH_YESNO, NON_AGGREGATE, ft_yesno, fc_volatile, FS_bitread, FS_w_mip, VISIBLE, {v:&BitReads[1]}, },
 	{"mission/frequency", PROPERTY_LENGTH_UNSIGNED, NON_AGGREGATE, ft_unsigned, fc_volatile, FS_r_samplerate, FS_w_samplerate, VISIBLE, NO_FILETYPE_DATA, },
 	{"mission/samples", PROPERTY_LENGTH_UNSIGNED, NON_AGGREGATE, ft_unsigned, fc_volatile, FS_r_3byte, NO_WRITE_FUNCTION, VISIBLE, {s:0x021A}, },
@@ -346,6 +347,15 @@
 	return FS_w_sibling_bitwork( Y, mask, "ControlRegister", owq ) ;
 }
 
+static ZERO_OR_ERROR FS_clrmem(struct one_wire_query *owq)
+{
+	/* clear memory */
+	if OWQ_Y(owq) {
+		return GB_to_Z_OR_E( OW_clearmemory(PN(owq)) ) ;
+	}
+	return 0;
+}
+
 static ZERO_OR_ERROR FS_r_statusbit(struct one_wire_query *owq)
 {
 	UINT U = 0 ;
@@ -887,6 +897,9 @@
 	/* write 0x020E -- 0x0214 */
 	BYTE data[] = { 0x86, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, };
 
+	/* clear memory */
+	RETURN_BAD_IF_BAD( OW_clearmemory(PN(owq))) ;
+
 	/* Stop clock, no rollover, no delay, temp alarms on, alarms cleared */
 	if ( BAD( OW_w_mem(data, 7, 0x020E, PN(owq)) ) ) {
 		return -EINVAL;
@@ -1109,8 +1122,10 @@
 
 static GOOD_OR_BAD OW_stopmission(struct parsedname *pn)
 {
-	BYTE data = 0x00;			/* dummy */
-	return OW_small_read(&data, 1, 0x0210, pn);
+	/* write 0 to bit 5 of status register 0x0214 to stop the mission */
+	BYTE data = 0xDF;
+
+	return OW_w_mem(&data, 1, 0x0214, pn);
 }
 
 static GOOD_OR_BAD OW_startmission(UINT freq, struct parsedname *pn)
@@ -1136,9 +1151,6 @@
 		UT_delay(1000);			/* wait for the clock to count a second */
 	}
 
-	/* clear memory */
-	RETURN_BAD_IF_BAD( OW_clearmemory(pn)) ;
-
 	/* finally, set the sample interval (to start the mission) */
 	data = BYTE_MASK(freq);
 	return OW_w_mem(&data, 1, 0x020D, pn);
diff -Naur owfs-2.9p0/src/man/DS1921.3 owfs-2.9p0-6/src/man/DS1921.3
--- owfs-2.9p0/src/man/DS1921.3	2012-09-21 22:19:43.000000000 +0200
+++ owfs-2.9p0-6/src/man/DS1921.3	2013-05-02 13:27:40.538508400 +0200
@@ -8,11 +8,11 @@
 '\" Free for all use. No waranty. None. Use at your own risk.
 '\" $Id: DS1921.3,v 1.21 2012/07/15 16:57:04 alfille Exp $
 '\"
-.TH DS1921-Thermachron 3  2005 "OWFS Manpage" "One-Wire File System"
+.TH DS1921-Thermochron 3  2005 "OWFS Manpage" "One-Wire File System"
 .SH NAME
 .TP
 .B DS1921
-Thermachron temperature logging iButton.
+Thermochron temperature logging iButton.
 .SH SYNOPSIS
 Temperature logging iButton.
 .PP
@@ -86,7 +86,7 @@
 Lowest temperature this
 .I DS1921
 can measure (in the current temperature scale).
-.SS abount/version
+.SS about/version
 .I read-only, ascii
 .br
 Specific
@@ -317,11 +317,7 @@
 .I mission
 the
 .B DS1921 (3)
-records temperature readings in a 2048-sample log and adds the to 62-bin histogram. more complete form of the
-.B DS2438 (3)
-battery chip. Current sensing is available, but not implemented. The major advantage compared to the
-.B DS2436 (3)
-is that two voltages can be read, allowing correcting circuit nmeasurements to supply voltage and temperature.
+records temperature readings in a 2048-sample log and adds them to a 62-bin histogram.
 .SH ADDRESSING
 .so addressing.3so
 .SH DATASHEET
diff -Naur owfs-2.9p0/src/man/DS2438.3 owfs-2.9p0-6/src/man/DS2438.3
--- owfs-2.9p0/src/man/DS2438.3	2012-09-21 22:19:44.000000000 +0200
+++ owfs-2.9p0-6/src/man/DS2438.3	2013-05-02 13:27:40.538508400 +0200
@@ -334,7 +334,7 @@
 .B DS2436
 battery chip. Current sensing is available, but not implemented. The major advantage compared to the
 .B DS2436
-is that two voltages can be read, allowing correcting circuit nmeasurements to supply voltage and temperature. A better comparison is the 
+is that two voltages can be read, allowing correcting circuit measurements to supply voltage and temperature. A better comparison is the 
 .B DS276x
 family of chips.
 .SH ADDRESSING