PSX Technical Information

@PS_2

Published in 

Playstation

 · 24 Nov 2019

 
Technical Information 

 

 
PSX DIAGRAM 

 

 

 

       CDROM <-------> CDROM DECODER 
CDROM BUFFER <----------//     | 
                        /      | 
                       /       | 
        /-------------/     R3000A <--> GTE >---\ 
SPEAKERS  <-- SPU <-----------/|\----------->  GPU --> SCREEN 
               |               |                | 
         SOUND BUFFER          |          FRAME BUFFER (VRAM) 
                               |  
                    SIO <------|------> PIO 
                   MDEC <------|------> OS ROM 
                              / \ 
                 MEMORY <----/   \----> PERIPHERICALS 

     Transfers:  MEMORY <---- DMA ----> BUFFERS 

 

 

 

1.CPU: MIPS RISC R3000A, 32 REGISTERS, CACHE: 4 Kbytes.  
2.GTE: (Geometry Transfer Engine) It uses matrices and vectors. Its results can be read by GPU.  
3.GPU: (Graphic Processing Unit).  
4.FRAME BUFFER: 1 Mbytes.  
5.SPU: (Sound Processing Unit), 24 voices, 44 KHz.  
6.SOUND BUFFER: 512 Kbytes.  
7.MDEC: It plays MPEG/JPEG.  
8.SIO: Serial Port.  
9.PIO: Parallel Port.  
10.MEMORY: 2 Mbytes.  
11.PERIPHERICALS: PADs/MEMORY CARDs/MOUSEs/MODEMs.  
12.OS ROM: 512 Kbytes.  

FILES 

 
1.EXE 

•Header: Bytes 0-2047 

Code Lenght : End Address - Load Address - 2048d 

00-07 ID: "PS-X EXE" 
16-19 Jump Address: first byte of code 
24-27 Load Address: first byte of EXE (including header) 
28-30 End Address: last byte of EXE (including header) 
48-51 Stack Address: first byte of stack 
00113 Territory : "E"=Europe, "U"=USA, "J"=Japan 
•Code: Bytes 2048-... 

 
2.SEQ 

•It seems that SEQ files are song files with MIDI (instruments or samples?).  
If that´s true I could easily play those files because some time ago (when I  
was 18) I did a program like Screamtracker with General MIDI interface. 

 

 
3.TIM 

•I´ll update this info in next days. 

 

 

 
RESOLUTIONS 

 
•Horizontal (pixels): 256, 320, 384, 512, 640 

•Vertical (pixels): 256(PAL), 512(PAL), 240(NTSC), 480(NTSC) 

•Colors: 16(CLUT), 256(CLUT), 65536(DIRECT), 16777216(DIRECT) 

 

 
Storing a pixel: 

•16, 256: unknowed. I think the way is the same as PC: first a pallete of x bytes,  
 later the body screen (each byte defines a color in the pallete) 

•65536 (32768+transparency bit):  

Each word defines a pixel like the following: 

word: (bit 31)TBBBBGGGGRRRR(bit 00) 

t=transparency bit (1 means transparency pixel) 

•16277216: I "suppose" it uses 3 bytes (standard way), but I don´t know. 

 

 

 
FRAME BUFFER (VRAM) 

 
•Virtual Area: 1024x512 words 

•There are two buffers in this area, GPU BUFFER#1 and GPU BUFFER#2. So this allows  
 PlayStation to Double Buffer. 

•The VRAM can be freely written and read, but by using DMA. 

•CLUTs are also located in the VRAM. It seems to be what limits the CLUTs is memory,  
 not a "number" of them. 

 

 

 
0,0-----------------------------------------------------...--1023,0 
|                          | |                               | 
|                          | | PAL:  255, 511                | 
|      GPU BUFFER #1       | |                               | 
|                          | | NTSC: 239, 479                | 
|<- 255,319,383,511,639 -->| v                               | 
|--------------------------|                                 | 
|                          |                                 | 
|                          |                                 | 
|      GPU BUFFER #2       |                                 | 
|                          |                                 | 
|                          |                                 | 
|--------------------------/                                 | 
|                                                            | 
|                                                            | 
|                                                            | 
|                                                            | 
.                                                            . 
.                                                            . 
.                                                            . 
|                                                            | 
|                                                            | 
0,511---------------------------------------------------...--1023,511 

 

 

 
CDROM 

 
•PSX CDROM seems to read ISO 9660 format. So files can be read directly from CD. 

•I´ve done a program which read audio tracks, but some games like Wipeout´2097 don´t  
 work in my Sony CDU33A CDROM (Prodigy Track). I don´t know *exactly* why it happens.