CPU

Overview

LSI CoreWare CW33300-based core

• MIPS R3000A-compatible 32-bit RISC CPU MIPS R3051 with 5 KB L1 cache, running at 33.8688 MHz
• The microprocessor was manufactured by LSI Logic Corp. with technology licensed from SGI
• Features:
  • Initial feature size (process node) was 0.5 micron (500 nm)
  • 850k – 1M transistors
  • Operating performance: 30 MIPS
  • Bus bandwidth 132 MB/s
  • One arithmetic/logic unit (ALU)
  • One shifter
• CPU cache:
  • 4 KB instruction cache
  • 1 KB non-associative SRAM data cache

Geometry Transformation Engine (GTE)

• Coprocessor that resides inside the main CPU processor, giving it additional vector math instructions used for 3D graphics, lighting, geometry, polygon and coordinate transformations - GTE performs high-speed matrix multiplications
• Operating performance: 66 MIPS
• Polygons per second (rendered in hardware):
  • 90,000 with texture mapping, lighting and Gouraud shading
  • 180,000 with texture mapping
  • 360,000 with flat shading

Motion Decoder (MDEC)

• Also residing within the main CPU, enables full screen, high quality FMV playback and is responsible for decompressing images and video into VRAM
• Operating performance: 80 MIPS
• Documented device mode is to read three RLE-encoded 16×16 macroblocks, run IDCT and assemble a single 16×16 RGB macroblock
• Output data may be transferred directly to GPU via DMA
• It is possible to overwrite IDCT matrix and some additional parameters, however MDEC internal instruction set was never documented
• It is directly connected to a CPU bus

System Control Coprocessor (Cop0)

• This unit is part of the CPU. Has 16 32-bit control registers
• Modified from the original R3000A cop0 architecture, with the addition of a few registers and functions
• Controls memory management through virtual memory technique, system interrupts, exception handling, and breakpoints

Revisions

CXD8530

• CXD8530Q
  • Found on some PU-7, very early/launch units
  • Die size: 128 mm², 1M transistors
  • Manufactured in 0.6 µm
  • Comes in a metal QFP package
• CXD8530AQ
  • Found on some PU-7, mostly early/launch units
  • Die size: 128 mm², 1M transistors
    • Not a die shrink; likely just some fixes and/or optimizations
  • Comes in a metal QFP package
• CXD8530BQ
  • Found on some PU-7
  • Die size: 66 mm²
    • Huge die shrink, a lot of changes
  • This revision and all later revisions are implemented in standard cells as an ASIC, which means there are less visible structures on the die
  • This revision and all later revisions come in a plastic QFP package
• CXD8530CQ
  • Found on some PU-8 and PU-16
  • Die size: 66 mm²
    • Not a die shrink; likely just some fixes and/or optimizations

CXD8606

From PU-18 onwards (SCPH-55XX), only CXD8606 was used.

• CXD8606Q
  • Found on some PU-8 and PU-18
  • Die size: 66 mm², 850k transistors
    • Not a die shrink; likely just some fixes and/or optimizations
• CXD8606AQ
  • Found on some very late PU-8 and on some PU-18
  • Die size: 26.5 mm²
    • Huge die shrink
• CXD8606BQ
  • Found on some PU-20 as well as PU-22, PU-23 and earlier PM-41
  • Die size: 26.5 mm²
    • Not a die shrink; likely just some fixes and/or optimizations
• CXD8606CQ
  • Found on later PM-41
  • Die size: 26.5 mm²
    • Not a die shrink; likely just some fixes and/or optimizations

CXD8661

• CXD8661R
  • Used in some arcade systems (Capcom ZN-2, Namco System 12)
  • Runs at considerably higher clock speeds

Pictures

Comparison

Properly scaled comparison of die shots of most PS1 CPU revisions. Created by @Siliconinsid (Siliconinsider)

Single dice

Relative size of these pictures is not to scale. See above for actual sizes.

Dieshot of CXD8530Q taken from Ken Kutaragis presentation at Hot Chips '99.	Dieshot of CXD8530CQ taken from zeptobars.com.	Dieshot of CXD8606BQ by TICS/onidev