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 the SH-2 turn each LSI on and off, set and acquire the calendar clock, and collect data from peripherals. Furthermore, the clock change command switches the horizontal resolution to 320 dots or 352 dots.
Figure 1.1 SMPC system configuration
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The SMPC has two sets of 7-bit parallel I/O ports.
Access to the I/O port is controlled by firmware inside the SMPC, and there are two access methods: SMPC control mode, which outputs collected data to the SMPC output register (OREG), and SH-2 direct mode, which allows direct access from the SH-2. You can select. For details on SMPC control mode and SH-2 direct mode, see Chapter 3 " ◆SMPC Control Mode " and " ◆SH-2 Direct Mode " respectively.
When the power is turned on, each unit inside the Saturn is initialized to the following state.
- ＜ Initial state when power is turned on＞
- Sound CPU OFF state
- Sound CPU has been reset. The SNDON command starts operation from the power-on vector.
- VDP1,VDP2,SCU,SCSP ON state
- It is now accessible from SH-2.
- Slave SH OFF state
- Slave SH-2 has a reset. The SSHON command starts the operation from the power-on vector.
- DOT SEL OFF state
- The PLL oscillation frequency is 320 mode (NTSC: 26.8741MHz, PAL: 26.6875MHz), and VDP1, VDP2, and SH-2 operate at this frequency. Operates in 352 mode (NTSC: 28.6364MHz, PAL: 28.4375MHz) with CKCHG352 command.
- CD block ON status
- It is now accessible from SH-2.
