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-rw-r--r--src/emu/machine/74153.c151
1 files changed, 151 insertions, 0 deletions
diff --git a/src/emu/machine/74153.c b/src/emu/machine/74153.c
new file mode 100644
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--- /dev/null
+++ b/src/emu/machine/74153.c
@@ -0,0 +1,151 @@
+/*****************************************************************************
+
+ 74153 Dual 4-line to 1-line data selectors/multiplexers
+
+
+ Pin layout and functions to access pins:
+
+ enable_w(0) [1] /1G VCC [16]
+ b_w [2] B /2G [15] enable_w(1)
+ input_line_w(0,3) [3] 1C3 A [14] a_w
+ input_line_w(0,2) [4] 1C2 2C3 [13] input_line_w(1,3)
+ input_line_w(0,1) [5] 1C1 2C2 [12] input_line_w(1,2)
+ input_line_w(0,0) [6] 1C0 2C1 [11] input_line_w(1,1)
+ output_r(0) [7] 1Y 2C0 [10] input_line_w(1,0)
+ [8] GND 2Y [9] output_r(1)
+
+
+ Truth table (all logic levels indicate the actual voltage on the line):
+
+ INPUTS | OUTPUT
+ |
+ G | B A | C0 C1 C2 C3 | Y
+ --+------+-------------+---
+1 H | X X | X X X X | L
+2 L | L L | X X X X | C0
+3 L | L H | X X X X | C1
+4 L | H L | X X X X | C2
+5 L | H H | X X X X | C3
+ --+------+-------------+---
+ L = lo (0)
+ H = hi (1)
+ X = any state
+
+*****************************************************************************/
+
+#include "driver.h"
+#include "machine/74153.h"
+
+
+#define MAX_TTL74153 9
+
+struct TTL74153
+{
+ /* callback */
+ void (*output_cb)(void);
+
+ /* inputs */
+ int a; /* pin 14 */
+ int b; /* pin 2 */
+ int input_lines[2][4]; /* pins 3-6,10-13 */
+ int enable[2]; /* pins 1,15 */
+
+ /* output */
+ int output[2]; /* pins 7,9 */
+
+ /* internals */
+ int last_output[2];
+};
+
+static struct TTL74153 chips[MAX_TTL74153];
+
+
+void TTL74153_update(int which)
+{
+ int sel;
+ int section;
+
+
+ sel = (chips[which].b << 1) | chips[which].a;
+
+
+ /* process both sections */
+ for (section = 0; section < 2; section++)
+ {
+ if (chips[which].enable[section])
+ chips[which].output[section] = 0; // row 1 in truth table
+ else
+ chips[which].output[section] = chips[which].input_lines[section][sel];
+ }
+
+
+ /* call callback if either of the outputs changed */
+ if ( chips[which].output_cb &&
+ ((chips[which].output[0] != chips[which].last_output[0]) ||
+ (chips[which].output[1] != chips[which].last_output[1])))
+ {
+ chips[which].last_output[0] = chips[which].output[0];
+ chips[which].last_output[1] = chips[which].output[1];
+
+ chips[which].output_cb();
+ }
+}
+
+
+void TTL74153_a_w(int which, int data)
+{
+ chips[which].a = data ? 1 : 0;
+}
+
+
+void TTL74153_b_w(int which, int data)
+{
+ chips[which].b = data ? 1 : 0;
+}
+
+
+void TTL74153_input_line_w(int which, int section, int input_line, int data)
+{
+ chips[which].input_lines[section][input_line] = data ? 1 : 0;
+}
+
+
+void TTL74153_enable_w(int which, int section, int data)
+{
+ chips[which].enable[section] = data ? 1 : 0;
+}
+
+
+int TTL74153_output_r(int which, int section)
+{
+ return chips[which].output[section];
+}
+
+
+
+void TTL74153_config(int which, const struct TTL74153_interface *intf)
+{
+ if (which >= MAX_TTL74153)
+ {
+ logerror("Only %d 74153's are supported at this time.\n", MAX_TTL74153);
+ return;
+ }
+
+
+ chips[which].output_cb = (intf ? intf->output_cb : 0);
+ chips[which].a = 1;
+ chips[which].b = 1;
+ chips[which].enable[0] = 1;
+ chips[which].enable[1] = 1;
+ chips[which].input_lines[0][0] = 1;
+ chips[which].input_lines[0][1] = 1;
+ chips[which].input_lines[0][2] = 1;
+ chips[which].input_lines[0][3] = 1;
+ chips[which].input_lines[1][0] = 1;
+ chips[which].input_lines[1][1] = 1;
+ chips[which].input_lines[1][2] = 1;
+ chips[which].input_lines[1][3] = 1;
+
+ chips[which].last_output[0] = -1;
+ chips[which].last_output[1] = -1;
+}