static READ8_HANDLER( pia_1_port_b_r )
{
UINT8 ret;
/* bit 4 - Player 4 steering input (wheel moving or stopped)
bit 5 - Player 3 steering input (wheel moving or stopped)
bit 6 - Player 2 steering input (wheel moving or stopped)
bit 7 - Player 1 steering input (wheel moving or stopped) */
ret = (TTL7474_output_r(TTL7474_1A_1) ? 0x10 : 0x00) |
(TTL7474_output_r(TTL7474_1C_1) ? 0x20 : 0x00) |
(TTL7474_output_r(TTL7474_1D_1) ? 0x40 : 0x00) |
(TTL7474_output_r(TTL7474_1F_1) ? 0x80 : 0x00);
return ret;
}
static READ8_HANDLER( pia_1_port_a_r )
{
UINT8 ret;
/* bit 0 - Player 4 steering input (left or right)
bit 1 - Player 3 steering input (left or right)
bit 2 - Player 2 steering input (left or right)
bit 3 - Player 1 steering input (left or right)
bit 4 - Player 4 forward/reverse input
bit 5 - Player 3 forward/reverse input
bit 6 - Player 2 forward/reverse input
bit 7 - Player 1 forward/reverse input */
ret = (TTL7474_output_r(TTL7474_1A_2) ? 0x01 : 0x00) |
(TTL7474_output_r(TTL7474_1C_2) ? 0x02 : 0x00) |
(TTL7474_output_r(TTL7474_1D_2) ? 0x04 : 0x00) |
(TTL7474_output_r(TTL7474_1F_2) ? 0x08 : 0x00) |
(readinputport(7) & 0xf0);
return ret;
}
static void galaxian_7474_9M_1_callback(void)
{
/* Q goes to the NMI line */
cpunum_set_input_line(0, irq_line, TTL7474_output_r(1) ? CLEAR_LINE : ASSERT_LINE);
}
