Explanation of words

Main CPU

It uses a RISC type CPU SH-2 that controls the entire system. The SH-2 is equipped with a 32-bit internal bus and an external bus.

VDP1

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

VDP2

Abbreviation for Video Display Processor 2. It has a scroll function that moves the screen up / down / left / right or rotates, and a priority function that determines the priority of many display screens and controls image processing such as color calculation and color offset.

SCSP

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

SMPC

Abbreviation for System Manager & Peripheal Control. It has reset management of the entire system, interface control with input devices (control pad, mouse, etc.), time display by real-time clock, battery backup function, etc.

data

A bit is the smallest unit that represents 0 or 1. 8 bits are collectively 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

Bus for connecting external devices such as ROM cassettes and CDs.

B_Bus

Bus to which VDP1, VDP2 and SCSP are connected.

Manual notation

The notation of this manual is as follows.

Binary number

Notated with a B at the end. For example, it is expressed as 100B. However, B may be omitted when it is 1 bit.

Hexadecimal

Notated with an H at the end. For example, it is expressed as 00H and FFH.

unit

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

MSB, LSB

The composition of bytes and words is that the left represents the high-order bit (MSB, most significant bit) and the right represents the low-order bit (LSB, least significant bit).

Undefined bit

Bits not defined by the instruction word are indicated by "-".

(R)

Indicates that the data is read-only.

(W)

Indicates that the data is for export only.

(R / W)

Indicates that the data is readable and writable.

++

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