Overview

This document summarizes the functions of the CD block and the external specifications of the CD communication interface.
The functions of the CD block are classified as shown in Table 1.1.

Table 1.1 Functional classification of CD blocks

Classification	Contents
CD part	Communication method, CD drive related, CD buffer related CD block file system related
MPEG part	MPEG related

The CD communication interface allows you to use the functions of the CD block with a common software interface.

1.1 Library configuration

Figure 1.1 shows the CD-related library structure.

Figure 1.1 CD-related library configuration

┌────────────────────────────────┐　
│ │　
│ Application │　
│ │　
└────────────────────────────────┘　
┌───────┐ ┌───────────┐ ┌────────┐　
│ MPEG │ │ Stream system │ │ File system │　
│ Library │ │ Library │ │ Library │　
│ │ │ ┌───┘ │ │　
│ │ │ │ ┌───┘ │　
│ │ │ │ │ │ │　
└───────┘└───────┘└─────┐ │　
┏━━━━━━━━━━━━━━━━━━━━━━━┓ │ │ │　
┃CD communication interface ┃││　
┗━━━━━━━━━━━┯━━━━━━━━━━━┛ └──┬───┘　
Software │ │　
━━━━━━━━━━━━━━━━━━━┿━━━━━━━━━━━━━━━━┿━━━━━━━━
Hardware │ │　
┌──────┴─────┐ ┌──────┴──────┐　
│ CD block │ │ SIMM, SCSI file │　
└────────────┘ └─────────────┘　

Alphabetic symbols that represent libraries, such as CDC, are called library symbols.
In this manual, the CD communication interface may be abbreviated as "CDC".

1.2 System configuration

Figure 1.2 shows the system configuration related to CD.

Figure 1.2 CD-related system configuration

The interface with the CD block refers to the main system as the host.
Also, the CD block is one of the subsystems.

(1) Communication with CD block

The host and the CD block communicate (command / response, data transfer) using registers on the hardware interface.
The command issued by the host to the CD block is called the CD block command. Usually abbreviated as "command".

(2) CD drive

The CD block communicates with the CD drive on a regular basis and controls the CD drive in response to commands from the host.
The CD drive supports the CD-ROM XA standard and multi-session. In addition, it is possible to switch between standard speed and double speed. (When playing a CD-DA, the standard speed is automatically set.)

1.3 Features and features

(1) to (3) are the functions of the CD communication interface, and (4) to (7) are the functions of the CD block.

(1) Communication function with CD block

1. A group of C language interface functions that communicate between the host and the CD block.
2. Issue a command to the CD block and receive a response.
3. There is almost a one-to-one correspondence with the CD block command.

(2) Auxiliary function of data transfer

It supports auxiliary functions related to data transfer, such as preparation / termination of data transfer and acquisition of the address of the data transfer register.
The data to be fetched and written to the CD block is transferred through the data transfer register of the CD block. The transfer itself does not go through the CD communication interface. A data transfer module such as DMA mediates. (Software transfer by CPU, DMA of CPU, DMA of SCU is possible)

(3) Register access function

Supports functions to access the registers of a CD block.

(4) CD drive function

Music playback (CD-DA) and sector read (CD-ROM) are handled by the same format command called CD playback.
Use the seek command to stop (stop) and pause (pause) CD playback, and use the CD playback command to resume (cancel) CD playback.

(5) Decoding function of subcodes R to W

Decodes subcodes R to W during CD-DA playback. There is a pack buffer for 24 packs to store the decoded pack data.

(6) Stream selection function

CD-ROM XA standard sectors and streams of various devices (host, MPEG, etc.) are processed in a unified manner.

1. There is a CD buffer for 200 sectors (about 460 Kbytes) to store the stream.
2. There are 24 independent selectors for selecting (separating / storing / retrieving) streams.

(7) CD block file system function (ISO9660)

Keep directory information inside a CD block for easy access to ISO9660 compliant files.