diff --git a/NEWS b/NEWS
index da4e42d0..e78362b3 100644
--- a/NEWS
+++ b/NEWS
@@ -29,6 +29,9 @@ Changes since version 7.0:
       to < 80 characters #1000
     - Dragon JTAG fix #979
     - adding support for all Linux baud rates v.2 #993
+    - Replace internal knowledge in jtag3.c by a public API #996
+    - JTAG3 UPDI EEPROM fix #1013
+    - Treat x bits in .conf SPI commands as 0 #943
 
   * Internals:
 
diff --git a/src/avr.c b/src/avr.c
index d6e78bb5..a8945d86 100644
--- a/src/avr.c
+++ b/src/avr.c
@@ -439,16 +439,16 @@ int avr_read(PROGRAMMER * pgm, AVRPART * p, char * memtype,
 	(vmem->tags[i] & TAG_ALLOCATED) != 0)
     {
       rc = pgm->read_byte(pgm, p, mem, i, mem->buf + i);
-      if (rc != 0) {
+      if (rc != LIBAVRDUDE_SUCCESS) {
         avrdude_message(MSG_INFO, "avr_read(): error reading address 0x%04lx\n", i);
-        if (rc == -1) {
+        if (rc == LIBAVRDUDE_GENERAL_FAILURE) {
           avrdude_message(MSG_INFO, "    read operation not supported for memory \"%s\"\n",
                           memtype);
-          return -2;
+          return LIBAVRDUDE_NOTSUPPORTED;
         }
         avrdude_message(MSG_INFO, "    read operation failed for memory \"%s\"\n",
                         memtype);
-        return rc;
+        return LIBAVRDUDE_SOFTFAIL;
       }
     }
     report_progress(i, mem->size, NULL);
@@ -1035,14 +1035,14 @@ int avr_signature(PROGRAMMER * pgm, AVRPART * p)
 
   report_progress (0,1,"Reading");
   rc = avr_read(pgm, p, "signature", 0);
-  if (rc < 0) {
+  if (rc < LIBAVRDUDE_SUCCESS) {
     avrdude_message(MSG_INFO, "%s: error reading signature data for part \"%s\", rc=%d\n",
                     progname, p->desc, rc);
     return rc;
   }
   report_progress (1,1,NULL);
 
-  return 0;
+  return LIBAVRDUDE_SUCCESS;
 }
 
 static uint8_t get_fuse_bitmask(AVRMEM * m) {
diff --git a/src/avrpart.c b/src/avrpart.c
index dc6def44..fdff0f78 100644
--- a/src/avrpart.c
+++ b/src/avrpart.c
@@ -82,11 +82,11 @@ int avr_set_bits(OPCODE * op, unsigned char * cmd)
   unsigned char mask;
 
   for (i=0; i<32; i++) {
-    if (op->bit[i].type == AVR_CMDBIT_VALUE) {
+    if (op->bit[i].type == AVR_CMDBIT_VALUE || op->bit[i].type == AVR_CMDBIT_IGNORE) {
       j = 3 - i / 8;
       bit = i % 8;
       mask = 1 << bit;
-      if (op->bit[i].value)
+      if (op->bit[i].value && op->bit[i].type == AVR_CMDBIT_VALUE)
         cmd[j] = cmd[j] | mask;
       else
         cmd[j] = cmd[j] & ~mask;
diff --git a/src/jtag3.c b/src/jtag3.c
index 6d358dfa..6a4004f3 100644
--- a/src/jtag3.c
+++ b/src/jtag3.c
@@ -313,6 +313,14 @@ static void jtag3_prmsg(PROGRAMMER * pgm, unsigned char * data, size_t len)
   }
 }
 
+static int jtag3_errcode(int reason)
+{
+  if (reason == RSP3_FAIL_OCD_LOCKED ||
+      reason == RSP3_FAIL_CRC_FAILURE)
+    return LIBAVRDUDE_SOFTFAIL;
+  return LIBAVRDUDE_GENERAL_FAILURE;
+}
+
 static void jtag3_prevent(PROGRAMMER * pgm, unsigned char * data, size_t len)
 {
   int i;
@@ -834,7 +842,7 @@ int jtag3_recv(PROGRAMMER * pgm, unsigned char **msg) {
   }
 }
 
- int jtag3_command(PROGRAMMER *pgm, unsigned char *cmd, unsigned int cmdlen,
+int jtag3_command(PROGRAMMER *pgm, unsigned char *cmd, unsigned int cmdlen,
 		   unsigned char **resp, const char *descr)
 {
   int status;
@@ -850,7 +858,7 @@ int jtag3_recv(PROGRAMMER * pgm, unsigned char **msg) {
       putc('\n', stderr);
     avrdude_message(MSG_NOTICE2, "%s: %s command: timeout/error communicating with programmer (status %d)\n",
                     progname, descr, status);
-    return -1;
+    return LIBAVRDUDE_GENERAL_FAILURE;
   } else if (verbose >= 3) {
     putc('\n', stderr);
     jtag3_prmsg(pgm, *resp, status);
@@ -858,9 +866,10 @@ int jtag3_recv(PROGRAMMER * pgm, unsigned char **msg) {
     avrdude_message(MSG_NOTICE2, "0x%02x (%d bytes msg)\n", (*resp)[1], status);
   }
 
-  c = (*resp)[1];
-  if ((c & RSP3_STATUS_MASK) != RSP3_OK) {
-    if ((c == RSP3_FAILED) && ((*resp)[3] == RSP3_FAIL_OCD_LOCKED)) {
+  c = (*resp)[1] & RSP3_STATUS_MASK;
+  if (c != RSP3_OK) {
+    if ((c == RSP3_FAILED) && ((*resp)[3] == RSP3_FAIL_OCD_LOCKED ||
+			       (*resp)[3] == RSP3_FAIL_CRC_FAILURE)) {
       avrdude_message(MSG_INFO,
 		      "%s: Device is locked! Chip erase required to unlock.\n",
 		      progname);
@@ -871,7 +880,7 @@ int jtag3_recv(PROGRAMMER * pgm, unsigned char **msg) {
     status = (*resp)[3];
     free(*resp);
     resp = 0;
-    return -status;
+    return jtag3_errcode(status);
   }
 
   return status;
@@ -987,7 +996,7 @@ static int jtag3_program_enable(PROGRAMMER * pgm)
     free(resp);
     PDATA(pgm)->prog_enabled = 1;
 
-    return 0;
+    return LIBAVRDUDE_SUCCESS;
   }
 
   return status;
@@ -1761,7 +1770,7 @@ static int jtag3_paged_write(PROGRAMMER * pgm, AVRPART * p, AVRMEM * m,
       free(cmd);
       return n_bytes;
     }
-    cmd[3] = ( p->flags & AVRPART_HAS_PDI ) ? MTYPE_EEPROM_XMEGA : MTYPE_EEPROM_PAGE;
+    cmd[3] = ( p->flags & AVRPART_HAS_PDI || p->flags & AVRPART_HAS_UPDI ) ? MTYPE_EEPROM_XMEGA : MTYPE_EEPROM_PAGE;
     PDATA(pgm)->eeprom_pageaddr = (unsigned long)-1L;
   } else if (strcmp(m->desc, "usersig") == 0 ||
              strcmp(m->desc, "userrow") == 0) {
diff --git a/src/jtag3_private.h b/src/jtag3_private.h
index a3e7fb08..7d0cbb74 100644
--- a/src/jtag3_private.h
+++ b/src/jtag3_private.h
@@ -144,6 +144,7 @@
 #  define RSP3_FAIL_WRONG_MODE          0x32 /* progmode vs. non-prog */
 #  define RSP3_FAIL_UNSUPP_MEMORY       0x34 /* unsupported memory type */
 #  define RSP3_FAIL_WRONG_LENGTH        0x35 /* wrong lenth for mem access */
+#  define RSP3_FAIL_CRC_FAILURE         0x43 /* CRC failure in device */
 #  define RSP3_FAIL_OCD_LOCKED          0x44 /* device is locked */
 #  define RSP3_FAIL_NOT_UNDERSTOOD      0x91
 
diff --git a/src/libavrdude.h b/src/libavrdude.h
index ddb72b48..46789f4f 100644
--- a/src/libavrdude.h
+++ b/src/libavrdude.h
@@ -27,6 +27,16 @@
 #include <stdint.h>
 
 typedef uint32_t pinmask_t;
+/*
+ * Values returned by library functions.
+ * Some library functions also return a count, i.e. a positive
+ * number greater than 0.
+ */
+#define LIBAVRDUDE_SUCCESS 0
+#define LIBAVRDUDE_GENERAL_FAILURE (-1)
+#define LIBAVRDUDE_NOTSUPPORTED (-2) // operation not supported
+#define LIBAVRDUDE_SOFTFAIL (-3) // returned by avr_signature() if caller
+                                 // might proceed with chip erase
 
 /* formerly lists.h */
 
diff --git a/src/main.c b/src/main.c
index 121e865e..8fabc13d 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1122,9 +1122,8 @@ int main(int argc, char * argv [])
     usleep(waittime);
     if (init_ok) {
       rc = avr_signature(pgm, p);
-      if (rc != 0) {
-        // -68 == -(0x44) == -(RSP3_FAIL_OCD_LOCKED)
-        if ((rc == -68) && (p->flags & AVRPART_HAS_UPDI) && (attempt < 1)) {
+      if (rc != LIBAVRDUDE_SUCCESS) {
+        if ((rc == LIBAVRDUDE_SOFTFAIL) && (p->flags & AVRPART_HAS_UPDI) && (attempt < 1)) {
           attempt++;
           if (pgm->read_sib) {
              // Read SIB and compare FamilyID