Chapter 2 Structure

■2.1 Hardware specifications

The hardware specifications of this machine are shown below.

Table 2.1 Hardware specifications＜ main system＞

CPU block	CPU	SH-2×2 32-bit RISC chip 28.6MHz Built-in multiplier/divider
	RAM	2MB
	ROM	512KB
	SCU	DMA 2ch DSP 14.3MHz
	SMPC	RTC 1MHz (accuracy) Peripheral interface adopted
video block	VDP1	Up to 400,000 pixels 1/60 second transfer
	VDP2	Screen resolution: 320 dots horizontally x 224 dots vertically, etc. Background screen Up to 5 screens
	RAM	For VDP1 512KB For VDP2 512KB
sound block	SCSP	PCM32ch maximum 44.1KHz DSP22.6MHz for sound effects only
	RAM	512KB
	CPU	MC68EC000 16-bit CISC 11.3MHz

Table 2.2 Hardware specifications＜ sub-system＞

CPU	SH-1 32-bit RISC chip 20.0MHz
RAM	512KB
MPEG AUDIO/VIDEO (option)	RAM 512KB Screen resolution: 704 dots horizontally x 480 dots vertically, etc. 30 frames per second video 44.1KHz 16 bit audio

■2.2 System configuration

The system configuration is equipped with a 32-bit RISC chip (SH-2) with built-in DSP functionality in the main unit's CPU, greatly improving computing power, etc. (Figure 2.1).

Figure 2.1 Block diagram

■2.3 Description of each part

The block diagram in Figure 2.1 is explained below.

●Main system side

SH-2(× 2)

The main CPU controls the entire system. It is a high-speed RISC type CPU that has significantly higher processing power than conventional systems. Since it has an internal computing unit similar to a DSP, computing power is dramatically improved.

MC68EC000

It has a 16-bit CPU for sound. Processing speed is faster than traditional systems.

RAM/ROM

There is a total of 24Mbits of RAM, with 16Mbits allocated to the main CPU, 4Mbits allocated to the sound CPU, and the remaining 8Mbits allocated to the video. The ROM contains the initial program for the hardware and the IPL program for the cartridge and CD. In addition to this, it also contains libraries for CDs, etc.

SMPC(System Manager & Peripheral Control)

Controls reset management of the entire system and interfaces with external devices such as control pads. It also has an internal RTC (Real Time Clock), so you can check the calendar and time. When the power is turned off, the RTC is backed up by a battery.

SCU (System Control Unit)

It controls each bus (A-bus, B-bus, CPU-bus) and acts as a co-processor for the main CPU. Since it is equipped with a DMA controller internally, it is possible to transfer character data to V-RAM while the main CPU is operating.

VDP1(Video Display Processor 1)

Control sprites (characters). In conventional systems, there was a limit to the number of sprites in the horizontal direction, but this limit has been removed, allowing more sprites (characters) to be displayed.
You can also display polygons in addition to sprites.

VDP2(Video Display Processor 2)

Controls the display of the background screen (=scroll screen) and the display priority. The simultaneous display of scroll screens can be extended to up to 5 screens, and the screen can be moved up, down, left and right, and rotated.

SCSP(Saturn Custom Sound Processor)

Controls the sound of the PCM/FM sound source. It supports the FM sound source of the conventional system and can even generate PCM sounds. Also, the sound quality has improved to the level of CD-D/A (Compact Disc - Digital / Audio).

Cartridge I/F

Connector I/F for cartridge. A maximum area of 57MB is available.

PAD I/F

Control pad connector I/F. There are two installed in the main body.

D/A converter, encoder

Changes the digital sound signal to an analog signal (D/A converter).
For colors (pictures), convert analog RGB to a video signal (encoder).

●Subsystem side

CPU

Performs mechanical control, error correction (C3), CD file management, etc.

RAM/ROM

RAM is used for CD buffer RAM, MPEG work RAM, data cache for CD error correction, etc. The ROM stores programs such as the CPU's CD BIOS.

CD-ROM drive

Adopts a 2x speed CD-ROM drive.

MPEG (MPEG is optional)

Full Screen, Full Color, Full Motion, and CD Quality Audio can be played under this standard. Up to 72 minutes (30 frames per second) of video and sound can be stored on a single CD. In addition to this, there are various applied functions that utilize MPEG functions, such as not only outputting the decompressed video but also importing it into the main system and processing it.