Chapter 2 Composition

■ 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 x 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) Adopting peripheral interface
Video block	VDP1	Up to 400,000 pixels 1/60 second transfer
	VDP2	Screen resolution 320 dots wide x 224 dots high Background screen Up to 5 screens
	RAM	512KB for VDP1 512KB for VDP2
Sound block	SCSP	PCM32ch up to 44.1KHz DSP22.6MHz for sound effects only
	RAM	512KB
	CPU	MC68EC000 16-bit CISC 11.3MHz

Table 2.2 Hardware specifications <subsystem>

CPU	SH-1 32-bit RISC chip 20.0MHz
RAM	512KB
MPEG AUDIO / VIDEO (option)	RAM 512KB Screen resolution 704 dots wide x 480 dots high, etc. 30 sheets / sec video 44.1KHz 16-bit audio

■ 2.2 System configuration

As for the system configuration, the CPU of the main unit is equipped with a 32-bit RISC chip (SH-2) with a built-in DSP function, which greatly improves computing power (Fig. 2.1).

Figure 2.1 Block diagram

■ 2.3 Explanation 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 RISC type high-speed CPU and has much processing power compared to conventional systems. Since it has a computing unit similar to a DSP inside, the computing power is dramatically improved.

MC68EC000

It has a 16-bit CPU for sound. The processing speed is faster than the conventional system.

RAM / ROM

The total RAM is 24M bits, 16M bits are allocated to the main CPU, 4M bits to the sound CPU, and 8M bits remaining to the video. The ROM contains the initials program for the hardware, the cartridge, and the IPL program for the CD. In addition to this, a library for CD etc. is also included.

SMPC (System Manager & Peripheral Control)

It controls the reset management of the entire system and the interface with external devices such as control pads. In addition, since it has an RTC (Real Time Clock) inside, you can know the calendar and time. When the power is turned off, the RTC is backed up by the battery.

SCU (System Control Unit)

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

VDP1 (Video Display Processor 1)

Controls sprites (characters). Whereas traditional systems have a limit on the number of sprites in the horizontal direction, you can remove the limit and display more sprites (characters).
You can also display polygons in addition to sprites.

VDP2 (Video Display Processor 2)

Controls the display of the background screen (= scroll screen) and controls the display priority. The simultaneous display of the scroll screen has been expanded to a maximum of 5 screens, and the screen can be moved up / down / left / 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 sound PCM. In addition, the sound quality has also risen to the level of CD-D / A (Compact Disc --Digital / Audio).

Cartridge I / F

Connector I / F for cartridges. Areas up to 57MB are available.

PAD I / F

This is the connector I / F of the control pad. Two are mounted on the main body.

D / A converter, encoder

Converts a digital sound signal to an analog signal (D / A converter).
For color (picture), convert analog RGB to video signal (encoder).

● Subsystem side

CPU

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

RAM / ROM

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

CD-ROM drive

It uses 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 application functions that utilize the MPEG function, such as not only outputting the stretched video but also importing it into the main system and processing it.