SYSTEM.CNF

System designation file that names the program to start from a disc.

Overview

SYSTEM.CNF is Sony's system designation file. It describes the PlayStation system settings and the application that is to be started.¹ The kernel reads the file at boot time and uses it to reserve memory for the stack, the tasks and the events.² The PS-X OS first checks the type of disc in the CD-ROM drive, and only an appropriate disc has its SYSTEM.CNF read and the named program executed.¹ The boot page describes the whole sequence.

Syntax

Each parameter is described from the beginning of a line in <key word> = <content> format. All characters are 1-byte uppercase alphanumerics, and lowercase characters may not be used. A space is necessary on both sides of the equal sign. When the same parameter appears more than once in a file, the first one found takes precedence.¹ The TCB and EVENT values are written in hexadecimal.²

Keywords

The parameters that may be described are shown below.

The PlayStation Operating System manual gives the STACK default as 0x8001FF00.¹ The Run-Time Library Overview and psx-spx both give 0x801FFF00, which is 256 bytes below the top of 2 MB of memory in segment B.²³

Limits

The number of task control blocks and event control blocks that can be allocated is limited by the formula TCB * 192 + EVENT * 32 + 544 < 4096.² The BIOS itself opens 5 events for its CD-ROM functions. Consequently, of the 16 events given by the default EVENT = 10, only 11 are available to the game.⁴

Boot Argument

The BOOT line may carry an argument string after the file name. The BIOS copies this string to the 128-byte area at address 0x00000180, where the executable may read it.³⁵

Boot File Name

Licensed games name the boot executable after the product code printed on the case. Because ISO 9660 level 1 allows only 8 characters in a base name, the minus sign is replaced by an underscore and the last two digits move into the extension, so SLUS-12345 becomes SLUS_123.45.³ The suffix ";1" is the ISO 9660 file version number. When a disc has no SYSTEM.CNF, the BIOS boots the file PSX.EXE instead.³

Example

A typical SYSTEM.CNF reads as follows.³

BOOT = cdrom:\SLUS_123.45;1
TCB = 4
EVENT = 10
STACK = 801FFF00

References