PS4 southbridge contains two processors named EMC and EAP on the same die that are mainly used on boot, during rest mode and for servicing.
The two processors are on the same die. It is a SoC (System on Chip).
EMC could stand for External Micro Controller. EMC was named MediaCon by some people when its name was still unknown.
The role of EMC is to load EMC IPL and EAP kernel, to be an interface for icc for the main APU kernel and Syscon and to offer a debug interface via UART that does not rely on Syscon or main APU. EMC runs its own FreeBSD kernel. It is a Marvell Armada, an ARM-based SoC. Sony stuck a PCIe bridge on it. It exposes ARM peripherals to the x86 side. There is some extra stuff (e.g. HPET, ACPI stuff).
EMC cpuid = 412FC231 (ARM Cortex-M3 r2p1). CPU clock: maybe about 100MHz.
EAP could stand for External Application Processor.
The role of EAP is to handle media (online Wireless/GbLAN, Bluray Drive and Harddrive) even in standby mode. EAP runs its own FreeBSD kernel in standby mode, activated to handle tasks such as downloading updates while the PS4 is in standby.
It handles several tasks to offload the APU:
- Network connections: Wireless and GbLAN, including background downloading and PlayGo
- File handling (Bluray Drive, Harddrive and USB 3.0), including background caching
- Main serial flash handling
EAP consists of Marvell PJ4C B0 rev 1 cores, ARMv7 CORTEX-A8 running FreeBSD 9 kernel. CPU clock: 500MHz. DDR clock: 800MHz.
As EAP Core software is unsigned, unencrypted and easily replaceable on PS4 HDD with a PS4 kernel exploit, it is possible to run homebrew code on EAP processor. See eapdev by Bigboss (psxdev).
Southbridge chip is connected to its own DDR3 SDRAM. It is named "sbram" as in SouthBridge RAM.
PS4 Fat and Slim
Southbridge contains a 256MB Serial flash.
There are three major hardware revisions, named Aeolia, Belize and Baikal.
See also Aeolia.
Southbridge revisions per chassis
|Model (chassis)||Motherboards||Southbridge Codename||Southbridge Labeling|
|7000||All NVA||Belize / ?Belize 2?||CXD90036G / ?CXD90046GG?|
|2100||All SAE||Belize 2 / Baikal||CXD90046GG|
Motherboards per southbridge revisions
|Southbridge Codename||Southbridge Labeling||Motherboards|