MIPS Assembly programming for the Playstation 1 (PS1/PSX)

The Playstation was Sony's first home console, While inferior in some ways to the more powerful N64, the Playstations huge storage capability, combined with an impressive game library saw the Playstation become the most popular console of the period, catapulting the playstation to the top of the console market.
Cpu 33.87 mhz  R3000 (MIPS I)
Ram 2MB
Video 1MB VRAM
Resolution 256x224 / 320x240 / 640x480

Memory Map

KUSEG KSEG0
(Cached)		 KSEG1
(Uncached)		 KSEG2
(IO Ports)		 Size Purpose
0x00000000 0x80000000 0xA0000000 -- 2048K 
Main RAM (first 64K reserved for BIOS)
0x1F000000 0x9F000000 0xBF000000 -- 8192K Expansion Region 1 (ROM/RAM)
0x1F800000 0x9F800000 -- -- 1K Scratchpad (D-Cache used as Fast RAM)
0x1F801000 0x9F801000 0xBF801000 -- 8K I/O Ports
0x1F802000 0x9F802000 0xBF802000 -- 8K Expansion Region 2 (I/O Ports)
0x1FA00000 0x9FA00000 0xBFA00000 -- 2048K Expansion Region 3 (whatever purpose)
0x1FC00000 
0x9FC00000 
0xBFC00000 
-- 512K BIOS ROM (Kernel) (4096K max)
-- -- -- 0xFFFE0000 
0.5K I/O Ports (Cache Control)

Gpu Commands

Written to port 0x1F801810

Function Byte 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Clear Cache 0 0x01 0
Function Byte 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Set Screen Width 0 0x06 End X Start X
Function Byte 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Send image to Framebuffer 0 0xA0
























1 Y X

2 H W

3 Pixel 2 Pixel 1

.. .. ...

n Pixel n*2+1 Pixel n*2
Function Byte 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0


Screen Memory

Each pixel is represented by one BIG ENDIAN word, in the format %-BBBBBGGGGGRRRRR

Endian

The N64 is BIG ENDIAN
the PSX is LITTLE ENDIAN