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---
title: System Architecture
type: component
summary: Processors and device groups of the PlayStation and how they connect.
category: Hardware
---

## Overview

The PlayStation is made up of processors and device groups centered on a 32-bit RISC CPU. Together they implement all functions such as graphics and sound.[^hw13]

The PlayStation has the following blocks:

Table: System blocks

| Block | Description |
| --- | --- |
| [CPU](/hardware/cpu/)[^hw13] | R3000A-based 32-bit RISC CPU with I-cache and scratchpad |
| GTE | Graphics data generating processor |
| [GPU](/hardware/gpu/) | Graphics data drawing processor with its frame buffer |
| [SPU](/hardware/spu/) | Audio processor with its sound buffer |
| MDEC | Motion decoder |
| [CD-ROM decoder](/hardware/cd-rom/) | CD-ROM decoder with its CD-ROM buffer |
| PIO | Extended parallel port |
| SIO | Extended serial port |
| OS ROM | OS kernel and boot loader |

## CPU and Its Peripherals

Main memory and an interrupt controller surround the 32-bit RISC CPU at the base of the PlayStation.[^hw14]

The CPU contains an instruction cache and a scratchpad memory.[^hw14]

## Graphics System

The graphics system is made up of the GTE and the GPU.[^hw14]

The GTE is a coprocessor of the CPU. It performs fixed-point matrix and vector operations for coordinate transformation and light source calculation.[^hw14]

The GPU draws polygons on instructions from the CPU. The frame buffer is mapped in its own 2-dimensional address space.[^hw14]

The CPU transfers texture images and color palettes (CLUT) to the frame buffer. The GPU then draws polygons from the coordinates and colors that the GTE computes.[^hw14]

## Sound System

The sound system is made up of the SPU and the CD-ROM decoder.[^hw14]

The SPU is a 24-voice ADPCM sound source operated by the CPU. It has its own address space with the sound buffer mapped in it.[^hw14]

The CPU transfers ADPCM data to the sound buffer. Key On, Key Off and modulation information from the CPU make the SPU play it.[^hw14]

## CD-ROM System

The CD-ROM system is made up of the drive, the decoder and the other parts needed to read a CD-ROM.[^hw15]

## Data Expansion Engine

The data expansion engine (MDEC) performs the inverse DCT at high speed. It expands JPEG data and MPEG data compressed within the frame only.[^hw15]

## Controller

The controller passes the player's input to the application. A Multi tap connects more controllers than the two connectors on the main unit.[^hw15]

## Memory Card

The Memory Card stores data that must survive a reset or power off. A Multi tap connects more cards than the two connectors on the main unit.[^hw15]

## Expansion Ports

The PlayStation has two types of expansion port: serial and parallel.[^hw15]

## References

[^hw13]: Sony Computer Entertainment Inc. PlayStation Hardware. August 1998. Page 1-3, Figure 1-1.
[^hw14]: Sony Computer Entertainment Inc. PlayStation Hardware. August 1998. Page 1-4, Figure 1-2.
[^hw15]: Sony Computer Entertainment Inc. PlayStation Hardware. August 1998. Page 1-5, Figure 1-3.