diff options
Diffstat (limited to 'trunk/src/emu/machine/74153.c')
-rw-r--r-- | trunk/src/emu/machine/74153.c | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/trunk/src/emu/machine/74153.c b/trunk/src/emu/machine/74153.c new file mode 100644 index 00000000000..cbb44d251ff --- /dev/null +++ b/trunk/src/emu/machine/74153.c @@ -0,0 +1,188 @@ +/***************************************************************************** + + 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); |