explanation of words

Main CPU

A RISC type CPU SH-2 is used to control the entire system. SH-2 is equipped with a 32-bit internal bus and external bus.

VDP1

Abbreviation for Video Display Processor 1. It has functions such as drawing characters and lines, specifying colors, calculating glow shading colors, specifying screen output coordinates, and controlling frame buffer display.

VDP2

Abbreviation for Video Display Processor 2. It has a scroll function that moves the screen vertically, horizontally, and rotationally, and a priority function that determines the priority order of multiple display screens and controls image processing such as color calculations and color offsets.

SCSP

Abbreviation for Saturn Custom Sound Processor. A multifunctional game sound source LSI that combines a PCM sound source and sound DSP.

SMPC

Abbreviation for System Manager & Peripheral Control. It has functions such as reset management of the entire system, interface control with input devices (control pad, mouse, etc.), time display using a real-time clock, and battery backup function.

data

A bit is the smallest unit that represents 0 or 1. 8 bits collectively are called a byte, 16 bits (or 2 bytes) are called a word, and 32 bits (or 4 bytes) are called a long word.

A_Bus

This is a bus for connecting external devices such as ROM cassettes and CDs.

B_Bus

This is the bus to which VDP1, VDP2, and SCSP are connected.

Manual conventions

The notation used in this manual is as follows.

Binary number

It is written with B at the end. For example, represent it as 100B. However, when it is 1 bit, B may be omitted.

Hexadecimal

It is written with H at the end. For example, it is expressed as 00H, FFH.

unit

1KByte represents 1,024Byte. 1Mbit is 1,048,576bit.

MSB, LSB

In the structure of bytes and words, the left side represents the most significant bit (MSB) and the right side represents the least significant bit (LSB).

undefined bit

Bits that are not defined in the instruction word are expressed as "-".

(R)

Indicates that the data is read-only.

(W)

Indicates that the data is export-only.

(R/W)

Indicates that the data is readable and writable.

++

Represents an increment. For example, to increment the CT0 register, write it as CT0++.