SMPC manages the reset control of the Saturn system when the power is turned on and the NMI request to the master SH-2 when the reset button is pressed. In addition, commands from SH-2 are used to turn on / off each LSI, set and acquire calendar clocks, and collect data from peripherals. In addition, the clock change command switches the horizontal resolution to 320 dots or 352 dots. Figure 1.1 SMPC system configuration
The SMPC has two sets of 7-bit parallel I / O ports.
Access to the I / O port is controlled by the firmware inside the SMPC, and there are two access methods: SMPC control mode, which outputs the collected data to the SMPC output register (OREG), and SH-2 direct mode, which can be accessed directly from SH-2. You can select. For details on SMPC control mode and SH-2 direct mode, refer to Chapter 3, " ◆ SMPC control mode " and " ◆ SH-2 direct mode, " respectively.
When the power is turned on, each unit inside Saturn will be initialized to the following state.- <Initial state when power is turned on>
- Sound CPU OFF state
- The sound CPU has a reset. Start from the power-on vector with the SNDON command.
- VDP1, VDP2, SCU, SCSP ON status
- It is accessible from SH-2.
- Slave SH OFF state
- The slave SH-2 has a reset. Start from the power-on vector with the SSHON command.
- DOT SEL OFF state
- The PLL oscillation frequency is 320 mode (NTSC: 26.8741MHz, PAL: 26.6875MHz), and VDP1, VDP2, and SH-2 are operating at this frequency. It operates in 352 mode (NTSC: 28.6364MHz, PAL: 28.4375MHz) with the CKCHG352 command.
- CD block ON state
- It is accessible from SH-2.
