diff --git a/src/mess/drivers/hh_hmcs40.c b/src/mess/drivers/hh_hmcs40.c
index 4bdbd69b069..5bc8225b84c 100644
--- a/src/mess/drivers/hh_hmcs40.c
+++ b/src/mess/drivers/hh_hmcs40.c
@@ -107,7 +107,7 @@ void hh_hmcs40_state::machine_start()
 {
 	// zerofill
 	memset(m_display_state, 0, sizeof(m_display_state));
-	memset(m_display_cache, 0, sizeof(m_display_cache));
+	memset(m_display_cache, ~0, sizeof(m_display_cache));
 	memset(m_display_decay, 0, sizeof(m_display_decay));
 	memset(m_display_segmask, 0, sizeof(m_display_segmask));
 	
diff --git a/src/mess/drivers/hh_pic16.c b/src/mess/drivers/hh_pic16.c
index bdabf44dd43..566c109ece2 100644
--- a/src/mess/drivers/hh_pic16.c
+++ b/src/mess/drivers/hh_pic16.c
@@ -76,7 +76,7 @@ void hh_pic16_state::machine_start()
 {
 	// zerofill
 	memset(m_display_state, 0, sizeof(m_display_state));
-	memset(m_display_cache, 0, sizeof(m_display_cache));
+	memset(m_display_cache, ~0, sizeof(m_display_cache));
 	memset(m_display_decay, 0, sizeof(m_display_decay));
 	memset(m_display_segmask, 0, sizeof(m_display_segmask));
 	
diff --git a/src/mess/drivers/hh_tms1k.c b/src/mess/drivers/hh_tms1k.c
index 6e86d6489f3..63551c2c631 100644
--- a/src/mess/drivers/hh_tms1k.c
+++ b/src/mess/drivers/hh_tms1k.c
@@ -17,7 +17,7 @@
  @MP0914   TMS1000  1979, Entex Baseball 1
  *MP0923   TMS1000? 1979, Entex Baseball 2
  @MP1030   TMS1100  1980, APF Mathemagician
- *MP1133   ?        1979, Kosmos Astro
+ *MP1133   TMS1470  1979, Kosmos Astro
  @MP1204   TMS1100  1980, Entex Baseball 3
  *MP1221   TMS1100  1980, Entex Raise The Devil
  *MP1312   TMS1100  198?, Tandy/RadioShack Science Fair Microcomputer Trainer
@@ -216,7 +216,7 @@ void hh_tms1k_state::machine_start()
 {
 	// zerofill
 	memset(m_display_state, 0, sizeof(m_display_state));
-	memset(m_display_cache, 0, sizeof(m_display_cache));
+	memset(m_display_cache, ~0, sizeof(m_display_cache));
 	memset(m_display_decay, 0, sizeof(m_display_decay));
 	memset(m_display_segmask, 0, sizeof(m_display_segmask));
 	
diff --git a/src/mess/drivers/hh_ucom4.c b/src/mess/drivers/hh_ucom4.c
index c31c962d08f..1210d58492f 100644
--- a/src/mess/drivers/hh_ucom4.c
+++ b/src/mess/drivers/hh_ucom4.c
@@ -117,7 +117,7 @@ void hh_ucom4_state::machine_start()
 {
 	// zerofill
 	memset(m_display_state, 0, sizeof(m_display_state));
-	memset(m_display_cache, 0, sizeof(m_display_cache));
+	memset(m_display_cache, ~0, sizeof(m_display_cache));
 	memset(m_display_decay, 0, sizeof(m_display_decay));
 	memset(m_display_segmask, 0, sizeof(m_display_segmask));
 	
diff --git a/src/mess/drivers/ticalc1x.c b/src/mess/drivers/ticalc1x.c
index 076d49c7000..f5a948a58db 100644
--- a/src/mess/drivers/ticalc1x.c
+++ b/src/mess/drivers/ticalc1x.c
@@ -99,7 +99,7 @@ void ticalc1x_state::machine_start()
 {
 	// zerofill
 	memset(m_display_state, 0, sizeof(m_display_state));
-	memset(m_display_cache, 0, sizeof(m_display_cache));
+	memset(m_display_cache, ~0, sizeof(m_display_cache));
 	memset(m_display_decay, 0, sizeof(m_display_decay));
 	memset(m_display_segmask, ~0, sizeof(m_display_segmask)); // !
 	
diff --git a/src/mess/drivers/tispeak.c b/src/mess/drivers/tispeak.c
index df40fbf214f..4c941d6cc23 100644
--- a/src/mess/drivers/tispeak.c
+++ b/src/mess/drivers/tispeak.c
@@ -731,7 +731,7 @@ void tispeak_state::machine_start()
 {
 	// zerofill
 	memset(m_display_state, 0, sizeof(m_display_state));
-	memset(m_display_cache, 0, sizeof(m_display_cache));
+	memset(m_display_cache, ~0, sizeof(m_display_cache));
 	memset(m_display_decay, 0, sizeof(m_display_decay));
 	memset(m_display_segmask, ~0, sizeof(m_display_segmask)); // !