diff --git a/flash.h b/flash.h
index 2951c4d..d0b4fd9 100644
--- a/flash.h
+++ b/flash.h
@@ -120,6 +120,26 @@
 #define FEATURE_OTP		(1 << 8)
 #define FEATURE_QPI		(1 << 9)
 
+enum test_state {
+	OK = 0,
+	NT = 1,	/* Not tested */
+	BAD,	/* Known to not work */
+	DEP,	/* Support depends on configuration (e.g. Intel flash descriptor) */
+	NA,	/* Not applicable (e.g. write support on ROM chips) */
+};
+
+#define TEST_UNTESTED	(struct tested){ .probe = NT, .read = NT, .erase = NT, .write = NT }
+
+#define TEST_OK_PROBE	(struct tested){ .probe = OK, .read = NT, .erase = NT, .write = NT }
+#define TEST_OK_PR	(struct tested){ .probe = OK, .read = OK, .erase = NT, .write = NT }
+#define TEST_OK_PRE	(struct tested){ .probe = OK, .read = OK, .erase = OK, .write = NT }
+#define TEST_OK_PREW	(struct tested){ .probe = OK, .read = OK, .erase = OK, .write = OK }
+
+#define TEST_BAD_PROBE	(struct tested){ .probe = BAD, .read = NT, .erase = NT, .write = NT }
+#define TEST_BAD_PR	(struct tested){ .probe = BAD, .read = BAD, .erase = NT, .write = NT }
+#define TEST_BAD_PRE	(struct tested){ .probe = BAD, .read = BAD, .erase = BAD, .write = NT }
+#define TEST_BAD_PREW	(struct tested){ .probe = BAD, .read = BAD, .erase = BAD, .write = BAD }
+
 struct flashctx;
 typedef int (erasefunc_t)(struct flashctx *flash, unsigned int addr, unsigned int blocklen);
 
@@ -143,11 +163,13 @@
 	unsigned int page_size;
 	int feature_bits;
 
-	/*
-	 * Indicate if flashrom has been tested with this flash chip and if
-	 * everything worked correctly.
-	 */
-	uint32_t tested;
+	/* Indicate how well flashrom supports different operations of this flash chip. */
+	struct tested {
+		enum test_state probe;
+		enum test_state read;
+		enum test_state erase;
+		enum test_state write;
+	} tested;
 
 	int (*probe) (struct flashctx *flash);
 
@@ -192,27 +214,6 @@
 	struct registered_programmer *pgm;
 };
 
-#define TEST_UNTESTED	0
-
-#define TEST_OK_PROBE	(1 << 0)
-#define TEST_OK_READ	(1 << 1)
-#define TEST_OK_ERASE	(1 << 2)
-#define TEST_OK_WRITE	(1 << 3)
-#define TEST_OK_PR	(TEST_OK_PROBE | TEST_OK_READ)
-#define TEST_OK_PRE	(TEST_OK_PROBE | TEST_OK_READ | TEST_OK_ERASE)
-#define TEST_OK_PRW	(TEST_OK_PROBE | TEST_OK_READ | TEST_OK_WRITE)
-#define TEST_OK_PREW	(TEST_OK_PROBE | TEST_OK_READ | TEST_OK_ERASE | TEST_OK_WRITE)
-#define TEST_OK_MASK	0x0f
-
-#define TEST_BAD_PROBE	(1 << 4)
-#define TEST_BAD_READ	(1 << 5)
-#define TEST_BAD_ERASE	(1 << 6)
-#define TEST_BAD_WRITE	(1 << 7)
-#define TEST_BAD_EW	(TEST_BAD_ERASE | TEST_BAD_WRITE)
-#define TEST_BAD_REW	(TEST_BAD_READ | TEST_BAD_ERASE | TEST_BAD_WRITE)
-#define TEST_BAD_PREW	(TEST_BAD_PROBE | TEST_BAD_READ | TEST_BAD_ERASE | TEST_BAD_WRITE)
-#define TEST_BAD_MASK	0xf0
-
 /* Timing used in probe routines. ZERO is -2 to differentiate between an unset
  * field and zero delay.
  * 
@@ -265,12 +266,6 @@
 int read_buf_from_file(unsigned char *buf, unsigned long size, const char *filename);
 int write_buf_to_file(const unsigned char *buf, unsigned long size, const char *filename);
 
-enum test_state {
-	OK = 0,
-	NT = 1,	/* Not tested */
-	BAD
-};
-
 /* Something happened that shouldn't happen, but we can go on. */
 #define ERROR_NONFATAL 0x100
 
diff --git a/flashchips.c b/flashchips.c
index dee7d9e..027b996 100644
--- a/flashchips.c
+++ b/flashchips.c
@@ -2189,7 +2189,7 @@
 		.model_id	= ATMEL_AT26F004,
 		.total_size	= 512,
 		.page_size	= 256,
-		.tested		= TEST_BAD_WRITE,
+		.tested		= {.probe = NT, .read = NT, .erase = NT, .write = BAD },
 		.feature_bits	= FEATURE_WRSR_WREN,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -5915,7 +5915,7 @@
 		.model_id	= MACRONIX_MX23L3254,
 		.total_size	= 4096,
 		.page_size	= 256,
-		.tested		= TEST_OK_PR | TEST_BAD_EW,
+		.tested		= {.probe = OK, .read = OK, .erase = NA, .write = NA},
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
 		.write		= NULL, /* MX23L3254 is a mask ROM, so it is read-only */
diff --git a/flashrom.c b/flashrom.c
index b3661c1..a2851af 100644
--- a/flashrom.c
+++ b/flashrom.c
@@ -1791,32 +1791,43 @@
 			 "clone the contents of this chip (see man page for "
 			 "details).\n");
 	}
-	if (TEST_OK_MASK != (chip->tested & TEST_OK_MASK)) {
+
+	if ((chip->tested.erase == NA) && (chip->tested.write == NA)) {
+		msg_cdbg("This chip's main memory can not be erased/written by design.\n");
+	}
+
+	if ((chip->tested.probe == BAD) || (chip->tested.probe == NT) ||
+	    (chip->tested.read == BAD)  || (chip->tested.read == NT) ||
+	    (chip->tested.erase == BAD) || (chip->tested.erase == NT) ||
+	    (chip->tested.write == BAD) || (chip->tested.write == NT)){
 		msg_cinfo("===\n");
-		if (chip->tested & TEST_BAD_MASK) {
+		if ((chip->tested.probe == BAD) ||
+		    (chip->tested.read == BAD) ||
+		    (chip->tested.erase == BAD) ||
+		    (chip->tested.write == BAD)) {
 			msg_cinfo("This flash part has status NOT WORKING for operations:");
-			if (chip->tested & TEST_BAD_PROBE)
+			if (chip->tested.probe == BAD)
 				msg_cinfo(" PROBE");
-			if (chip->tested & TEST_BAD_READ)
+			if (chip->tested.read == BAD)
 				msg_cinfo(" READ");
-			if (chip->tested & TEST_BAD_ERASE)
+			if (chip->tested.erase == BAD)
 				msg_cinfo(" ERASE");
-			if (chip->tested & TEST_BAD_WRITE)
+			if (chip->tested.write == BAD)
 				msg_cinfo(" WRITE");
 			msg_cinfo("\n");
 		}
-		if ((!(chip->tested & TEST_BAD_PROBE) && !(chip->tested & TEST_OK_PROBE)) ||
-		    (!(chip->tested & TEST_BAD_READ) && !(chip->tested & TEST_OK_READ)) ||
-		    (!(chip->tested & TEST_BAD_ERASE) && !(chip->tested & TEST_OK_ERASE)) ||
-		    (!(chip->tested & TEST_BAD_WRITE) && !(chip->tested & TEST_OK_WRITE))) {
+		if ((chip->tested.probe == NT) ||
+		    (chip->tested.read == NT) ||
+		    (chip->tested.erase == NT) ||
+		    (chip->tested.write == NT)) {
 			msg_cinfo("This flash part has status UNTESTED for operations:");
-			if (!(chip->tested & TEST_BAD_PROBE) && !(chip->tested & TEST_OK_PROBE))
+			if (chip->tested.probe == NT)
 				msg_cinfo(" PROBE");
-			if (!(chip->tested & TEST_BAD_READ) && !(chip->tested & TEST_OK_READ))
+			if (chip->tested.read == NT)
 				msg_cinfo(" READ");
-			if (!(chip->tested & TEST_BAD_ERASE) && !(chip->tested & TEST_OK_ERASE))
+			if (chip->tested.erase == NT)
 				msg_cinfo(" ERASE");
-			if (!(chip->tested & TEST_BAD_WRITE) && !(chip->tested & TEST_OK_WRITE))
+			if (chip->tested.write == NT)
 				msg_cinfo(" WRITE");
 			msg_cinfo("\n");
 		}
@@ -1859,7 +1870,7 @@
 
 	if (read_it || erase_it || write_it || verify_it) {
 		/* Everything needs read. */
-		if (chip->tested & TEST_BAD_READ) {
+		if (chip->tested.read == BAD) {
 			msg_cerr("Read is not working on this chip. ");
 			if (!force)
 				return 1;
@@ -1873,7 +1884,11 @@
 	}
 	if (erase_it || write_it) {
 		/* Write needs erase. */
-		if (chip->tested & TEST_BAD_ERASE) {
+		if (chip->tested.erase == NA) {
+			msg_cerr("Erase is not possible on this chip.\n");
+			return 1;
+		}
+		if (chip->tested.erase == BAD) {
 			msg_cerr("Erase is not working on this chip. ");
 			if (!force)
 				return 1;
@@ -1886,7 +1901,11 @@
 		}
 	}
 	if (write_it) {
-		if (chip->tested & TEST_BAD_WRITE) {
+		if (chip->tested.write == NA) {
+			msg_cerr("Write is not possible on this chip.\n");
+			return 1;
+		}
+		if (chip->tested.write == BAD) {
 			msg_cerr("Write is not working on this chip. ");
 			if (!force)
 				return 1;
diff --git a/print.c b/print.c
index fd4b2a7..8ca99d5 100644
--- a/print.c
+++ b/print.c
@@ -249,38 +249,46 @@
 		for (i = curdevlen; i < maxchiplen; i++)
 			msg_ginfo(" ");
 
-		if ((chip->tested & TEST_OK_PROBE))
+		if (chip->tested.probe == OK)
 			msg_ginfo("P");
+		else if (chip->tested.probe == NA)
+			msg_ginfo("-");
 		else
 			msg_ginfo(" ");
-		if ((chip->tested & TEST_OK_READ))
+		if (chip->tested.read == OK)
 			msg_ginfo("R");
+		else if (chip->tested.read == NA)
+			msg_ginfo("-");
 		else
 			msg_ginfo(" ");
-		if ((chip->tested & TEST_OK_ERASE))
+		if (chip->tested.erase == OK)
 			msg_ginfo("E");
+		else if (chip->tested.erase == NA)
+			msg_ginfo("-");
 		else
 			msg_ginfo(" ");
-		if ((chip->tested & TEST_OK_WRITE))
+		if (chip->tested.write == OK)
 			msg_ginfo("W");
+		else if (chip->tested.write == NA)
+			msg_ginfo("-");
 		else
 			msg_ginfo(" ");
 		for (i = 0; i < border; i++)
 			msg_ginfo(" ");
 
-		if ((chip->tested & TEST_BAD_PROBE))
+		if (chip->tested.probe == BAD)
 			msg_ginfo("P");
 		else
 			msg_ginfo(" ");
-		if ((chip->tested & TEST_BAD_READ))
+		if (chip->tested.read == BAD)
 			msg_ginfo("R");
 		else
 			msg_ginfo(" ");
-		if ((chip->tested & TEST_BAD_ERASE))
+		if (chip->tested.erase == BAD)
 			msg_ginfo("E");
 		else
 			msg_ginfo(" ");
-		if ((chip->tested & TEST_BAD_WRITE))
+		if (chip->tested.write == BAD)
 			msg_ginfo("W");
 		else
 			msg_ginfo(" ");
diff --git a/print_wiki.c b/print_wiki.c
index 5dcc4b6..cad6fef 100644
--- a/print_wiki.c
+++ b/print_wiki.c
@@ -249,7 +249,6 @@
 static void print_supported_chips_wiki(int cols)
 {
 	unsigned int lines_per_col;
-	uint32_t t;
 	char *s;
 	char vmax[6];
 	char vmin[6];
@@ -287,7 +286,35 @@
 			c = !c;
 
 		old = f;
-		t = f->tested;
+		const char *probe, *read, *write, *erase;
+		switch (f->tested.probe) {
+			case OK: probe = "OK"; break;
+			case BAD: probe = "No"; break;
+			case NA: probe = "NA"; break;
+			case DEP: probe = "Dep"; break;
+			default: probe = "?3"; break;
+		}
+		switch (f->tested.read) {
+			case OK: read = "OK"; break;
+			case BAD: read = "No"; break;
+			case NA: read = "NA"; break;
+			case DEP: read = "Dep"; break;
+			default: read = "?3"; break;
+		}
+		switch (f->tested.erase) {
+			case OK: erase = "OK"; break;
+			case BAD: erase = "No"; break;
+			case NA: erase = "NA"; break;
+			case DEP: erase = "Dep"; break;
+			default: erase = "?3"; break;
+		}
+		switch (f->tested.write) {
+			case OK: write = "OK"; break;
+			case BAD: write = "No"; break;
+			case NA: write = "NA"; break;
+			case DEP: write = "Dep"; break;
+			default: write = "?3"; break;
+		}
 		s = flashbuses_to_text(f->bustype);
 		sprintf(vmin, "%0.03f", f->voltage.min / (double)1000);
 		sprintf(vmax, "%0.03f", f->voltage.max / (double)1000);
@@ -298,16 +325,9 @@
 		       "|| %s || %s \n",
 		       (c == 1) ? "eeeeee" : "dddddd", f->vendor, f->name,
 		       f->total_size, s,
-		       (t & TEST_OK_PROBE) ? "OK" :
-		       (t & TEST_BAD_PROBE) ? "No" : "?3",
-		       (t & TEST_OK_READ) ? "OK" :
-		       (t & TEST_BAD_READ) ? "No" : "?3",
-		       (t & TEST_OK_ERASE) ? "OK" :
-		       (t & TEST_BAD_ERASE) ? "No" : "?3",
-		       (t & TEST_OK_WRITE) ? "OK" :
-		       (t & TEST_BAD_WRITE) ? "No" : "?3",
-		       f->voltage.min ? vmin : "N/A",
-		       f->voltage.min ? vmax : "N/A");
+		       probe, read, erase, write,
+		       f->voltage.min ? vmin : "?",
+		       f->voltage.max ? vmax : "?");
 		free(s);
 
 		if (((i % lines_per_col) + 1) == lines_per_col)