diff --git a/src/emu/sound/ay8910.c b/src/emu/sound/ay8910.c
index 6831a49b7fc..71ba0dc161f 100644
--- a/src/emu/sound/ay8910.c
+++ b/src/emu/sound/ay8910.c
@@ -868,6 +868,7 @@ void ay8910_write_ym(void *chip, int addr, int data)
 int ay8910_read_ym(void *chip)
 {
 	ay8910_context *psg = (ay8910_context *)chip;
+	device_type chip_type = psg->device->type();
 	int r = psg->register_latch;
 
 	if (r > 15) return 0;
@@ -898,7 +899,21 @@ int ay8910_read_ym(void *chip)
 			logerror("%s: warning - read 8910 '%s' Port B\n",cpuexec_describe_context(psg->device->machine),psg->device->tag());
 		break;
 	}
-	return psg->regs[r];
+	
+	/* Depending on chip type, unused bits in registers may or may not be accessible.
+	Untested chips are assumed to regard them as 'ram'
+	Tested and confirmed on hardware:
+	- AY-3-8910: inaccessible bits (see masks below) read back as 0
+	- YM2149: no anomaly
+	*/
+	if (chip_type == AY8910) {
+		const UINT8 mask[0x10]={
+			0xff,0x0f,0xff,0x0f,0xff,0x0f,0x1f,0xff,0x1f,0x1f,0x1f,0xff,0xff,0x0f,0xff,0xff
+		};
+		
+		return psg->regs[r] & mask[r];
+	}
+	else return psg->regs[r];
 }
 
 /*************************************