Memory card



The NeoGeo (AES and some MVS) uses JEIDA V3 memory cards to store game saves and/or high scores. The original SNK-branded card could only hold 2KiB of data.

The official SNK memory card was a battery-based 2KiB card using a LH5116 CMOS SRAM chip and voltage switching circuitry. Data retention voltage: 2V. The SP-S2 system ROM can handle memory cards up to 16KiB. The card is embedded in CD systems as a 8KiB battery-backed RAM chip.

See the CARD call description for memory card operations.

=Data format=

The system ROM can handle 8 different card sizes (2K, 4K, 6K, 8K, 10K, 14K and 16K) and 4 different card types (8 bits wide, 16 bits wide, 16 bits wide "doubled", and "SNK ROM" cards).

All cards use the same format regardless of capacity.

The data is split into 5 regions:

Header
Always 128 bytes.

Directory
List of saves of 32, 64, 96, 128, 160, 192, 224 or 256 entries. The size depends on the card's capacity.

Each entry has the following format:

FAT 1
List of used blocks, of 64, 128, 192, or 256 entries. The size depends on the card's capacity.
 * $02 is a block reservd by the system ROM
 * $01 is a block used by a game
 * $00 is a free block

FAT 2
FAT 2 is simply a mirror of FAT 1.

Game Data
Many games use 64 bytes, but some might use more.

The first 20 bytes are the data title (usually the game and stage name).

=Registers=


 * Write is enabled if is 0 and  is 1
 * The WP (Write Protect) pin is read through bit 6 of
 * CD1 (Card Detect 1) is read through bit 4 of
 * CD2 (Card Detect 2) is read through bit 5 of
 * Attribute memory is selected if is 1

=Card pinout (top)=



=Card pinout (bottom)=