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-rw-r--r--src/devices/machine/74259.cpp21
1 files changed, 21 insertions, 0 deletions
diff --git a/src/devices/machine/74259.cpp b/src/devices/machine/74259.cpp
index e8632baf940..da6a7cfa99d 100644
--- a/src/devices/machine/74259.cpp
+++ b/src/devices/machine/74259.cpp
@@ -249,6 +249,27 @@ WRITE8_MEMBER(addressable_latch_device::write_d0)
}
//-------------------------------------------------
+// write_d1 - bus-triggered write handler using
+// second-lowest data bit
+//-------------------------------------------------
+
+WRITE8_MEMBER(addressable_latch_device::write_d1)
+{
+ if (LOG_MYSTERY_BITS && data != 0x00 && data != 0x02 && data != 0xff)
+ logerror("Mystery bits written to Q%d:%s%s%s%s%s%s%s\n",
+ offset,
+ BIT(data, 7) ? " D7" : "",
+ BIT(data, 6) ? " D6" : "",
+ BIT(data, 5) ? " D5" : "",
+ BIT(data, 4) ? " D4" : "",
+ BIT(data, 3) ? " D3" : "",
+ BIT(data, 2) ? " D2" : "",
+ BIT(data, 0) ? " D0" : "");
+
+ write_bit(offset, BIT(data, 1));
+}
+
+//-------------------------------------------------
// write_d7 - bus-triggered write handler using
// MSB of (8-bit) data
//-------------------------------------------------