Sega Mega CD
Sub-pages
Hardware Overview (Sega Mega CD)
The Mega CD circuit is mostly made up of the following chips: 68000 CPU (Motorola MC68000) Program RAM (512kb) for 68000...
Board Scans (Sega Mega CD)
You can find complete PCB and schematic redraws for all revisions here . This is great for allowing tracing of connecti...
Power Circuit (Sega Mega CD)
The Mega CD / Sega CD has a power circuit that is enabled when the Mega Drive / Genesis provides 9V power through the ...
Side Connector (Sega Mega CD)
The connector block that joins the Mega CD to the Mega Drive has several versions, and it must match the Mega CD motherb...
Boot Up Diagnostics (Mega CD)
To help diagnose what is wrong there are a few common issues that can help pin-point an issue. Make sure to use a known ...
First Stage Boot (Mega CD)
First stage boot is getting to the BIOS screen without any text displaying. This means the BIOS has been loaded into mem...
Second Stage Boot (Sega Mega CD)
Once the BIOS has been fully initialized it then loads the BIOS program into Program RAM, makes communication with the C...
Third Stage Boot (Mega CD)
Once you get to Second Stage Boot (the Mega CD BIOS screen to fully load with logo, disc tray opens and game starts to r...
Mega CD Engine Pinout (Sega Mega CD)
The Mega CD Engine, also known as the Gate Array, controls reading in and generating the overlay graphics used on top of...
Stuttering Skipping Audio (Sega Mega CD)
A common issue I have come across is when the Mega CD loads up, but it is as if every half second the sound cuts out, cr...
Game Save (Sega Mega CD)
The game saves are stored in the Work RAM (MB8464A, IC16). This Work RAM is enabled by the CS2 pin, which is controlled ...
FRAM Upgrade (Sega Mega CD)
You can perform an upgrade on the SRAM and battery module, upgrading it to an FRAM chip , meaning you will no longer re...
Region Free BIOS (Sega Mega CD)
If you have a single specific BIOS, such as an EU region free then you can just install it in place of the original. Mul...
BIOS File Headers (Sega Mega CD)
A useful resource when dealing with BIOS files is to know how their headers look so when you open a binary dump you can ...