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-rw-r--r--trunk/src/emu/machine/74153.c188
1 files changed, 188 insertions, 0 deletions
diff --git a/trunk/src/emu/machine/74153.c b/trunk/src/emu/machine/74153.c
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+++ b/trunk/src/emu/machine/74153.c
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+/*****************************************************************************
+
+ 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 "emu.h"
+#include "machine/74153.h"
+
+
+typedef struct _ttl74153_state ttl74153_state;
+struct _ttl74153_state
+{
+ /* callback */
+ void (*output_cb)(device_t *device);
+
+ /* 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];
+};
+
+INLINE ttl74153_state *get_safe_token(device_t *device)
+{
+ assert(device != NULL);
+ assert(device->type() == TTL74153);
+
+ return (ttl74153_state *)downcast<legacy_device_base *>(device)->token();
+}
+
+
+
+void ttl74153_update(device_t *device)
+{
+ ttl74153_state *state = get_safe_token(device);
+ int sel;
+ int section;
+
+
+ sel = (state->b << 1) | state->a;
+
+
+ /* process both sections */
+ for (section = 0; section < 2; section++)
+ {
+ if (state->enable[section])
+ state->output[section] = 0; // row 1 in truth table
+ else
+ state->output[section] = state->input_lines[section][sel];
+ }
+
+
+ /* call callback if either of the outputs changed */
+ if ( state->output_cb &&
+ ((state->output[0] != state->last_output[0]) ||
+ (state->output[1] != state->last_output[1])))
+ {
+ state->last_output[0] = state->output[0];
+ state->last_output[1] = state->output[1];
+
+ state->output_cb(device);
+ }
+}
+
+
+void ttl74153_a_w(device_t *device, int data)
+{
+ ttl74153_state *state = get_safe_token(device);
+ state->a = data ? 1 : 0;
+}
+
+
+void ttl74153_b_w(device_t *device, int data)
+{
+ ttl74153_state *state = get_safe_token(device);
+ state->b = data ? 1 : 0;
+}
+
+
+void ttl74153_input_line_w(device_t *device, int section, int input_line, int data)
+{
+ ttl74153_state *state = get_safe_token(device);
+ state->input_lines[section][input_line] = data ? 1 : 0;
+}
+
+
+void ttl74153_enable_w(device_t *device, int section, int data)
+{
+ ttl74153_state *state = get_safe_token(device);
+ state->enable[section] = data ? 1 : 0;
+}
+
+
+int ttl74153_output_r(device_t *device, int section)
+{
+ ttl74153_state *state = get_safe_token(device);
+ return state->output[section];
+}
+
+
+static DEVICE_START( ttl74153 )
+{
+ ttl74153_config *config = (ttl74153_config *)downcast<const legacy_device_base *>(device)->inline_config();
+ ttl74153_state *state = get_safe_token(device);
+ state->output_cb = config->output_cb;
+
+ device->save_item(NAME(state->enable));
+ device->save_item(NAME(state->last_output));
+ device->save_item(NAME(state->input_lines[0][0]));
+ device->save_item(NAME(state->input_lines[0][1]));
+ device->save_item(NAME(state->input_lines[0][2]));
+ device->save_item(NAME(state->input_lines[0][3]));
+ device->save_item(NAME(state->input_lines[1][0]));
+ device->save_item(NAME(state->input_lines[1][1]));
+ device->save_item(NAME(state->input_lines[1][2]));
+ device->save_item(NAME(state->input_lines[1][3]));
+ device->save_item(NAME(state->a));
+ device->save_item(NAME(state->b));
+}
+
+
+static DEVICE_RESET( ttl74153 )
+{
+ ttl74153_state *state = get_safe_token(device);
+
+ state->a = 1;
+ state->b = 1;
+ state->enable[0] = 1;
+ state->enable[1] = 1;
+ state->input_lines[0][0] = 1;
+ state->input_lines[0][1] = 1;
+ state->input_lines[0][2] = 1;
+ state->input_lines[0][3] = 1;
+ state->input_lines[1][0] = 1;
+ state->input_lines[1][1] = 1;
+ state->input_lines[1][2] = 1;
+ state->input_lines[1][3] = 1;
+
+ state->last_output[0] = -1;
+ state->last_output[1] = -1;
+}
+
+
+static const char DEVTEMPLATE_SOURCE[] = __FILE__;
+
+#define DEVTEMPLATE_ID(p,s) p##ttl74153##s
+#define DEVTEMPLATE_FEATURES DT_HAS_START | DT_HAS_RESET | DT_HAS_INLINE_CONFIG
+#define DEVTEMPLATE_NAME "74153"
+#define DEVTEMPLATE_FAMILY "TTL"
+#include "devtempl.h"
+
+DEFINE_LEGACY_DEVICE(TTL74153, ttl74153);