Difference between revisions of "Memory card"

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See the [[CARD]] BIOS call description for memory card operations.
 
See the [[CARD]] BIOS call description for memory card operations.
 
[[http://www.neogeoprotos.com/memcardfaq.htm (from neogeoprotos.com)]]
 
 
[[http://www.raregame.ru/file/15/NEO-GEO_Memcard_Data_Format.GIF Data format (from Raregame.ru)]]
 
  
 
=Data format=
 
=Data format=

Revision as of 05:54, 21 October 2012

JEIDA V3 memory cards used in AES and some MVS systems to store game saves and/or high scores. The original SNK card could only hold 2KiB of data. The Neogeo can use up to 8MiB (24 address lines but A23 never used) ?

Picture by HPMAN

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 BIOS can only handle 8bit memory cards up to 16KiB ? (bank checking while format up to $8000/2). Seems the file checking can only go up to 256 so 16 files * 16 games * 64 bytes = 16KiB too.

Replaced by a 8KiB fixed battery-backed RAM chip in the CD systems.

See the CARD BIOS call description for memory card operations.

Data format

BIOS can handle 8 different card size (2K, 4K, 6K, 8K, 10K, 14K and 16K) and different card type (8 bits wide, 16 bits wide, 16 bits doubled wide and SNK ROM card).

All the data here are for all the card, it's just a matter on how to read the data between different type of card.

The internal card data are splitted into 5 regions.

Header

Always $80 bytes.

Address Name Size Description
$0~$9 10 bytes Zero or "SNK ROM " (Development unit I think)

For 16bits doubled card, $6 is set to $0001

$A CARD_SIZE word Size of the memcard
$C byte 0
$D CARD_FAT_1_CHKSUM byte Checksum of the FAT 1
$E CARD_FAT_2_CHKSUM byte Checksum of the FAT 2
$F CARD_USERNAME_AVAILABLE byte 0 : Username available, !0 : Username unavailable
$10 CARD_USERNAME 16 bytes Card holder username
$20 CARD_MAGIC 16 bytes $4e $XX $45 $XX $4f $XX $2d $XX $47 $XX $45 $XX $4f $XX 80 $XX "NEO-GEO" + $80
$30 CARD_REGION byte Region of slot that formated the card, 0 = Japan, 1 = USA, 2 = Europe

Directory

List of saves. Size depends on card size, it can hold 32, 64, 96, 128, 160, 192, 224 or 256 entries.

Each entry have this format :

Address Size Description
$0 byte Game Sub number (CARD_SUB), 0 to 15. $FF if entry is free
$1 word Game NGH number
$3 byte FAT entry number (see below)

FAT 1

List of used blocks. Size depends on card size, it can hold 64, 128 192 or 256 entries. $02 is a BIOS reserved block $01 is a game used block $00 is a free block

FAT 2

FAT 2 is simply a mirror of FAT 1.

Game Data

Normally 64 bytes but maybe some games use more that one block ?

The first 20 bytes are the data title (generally the game name + the stage name).

Card pinout

LH5116 pinout
Pin Goes to Signal name PC Card name
1 GND
2 9 G0 MCD3 D3
3 11 G0 MCD4 D4
4 12 G0 MCD5 D5
5 13 G0 MCD6 D6
6 14 G0 MCD7 D7
7 42, 27 C1 CRDC /CE1
8 23 E0 Y10 A10
9 30 C1 CRDO /OE
10 24 E0 Y11 A11
11 22 E0 Y9 A9
12 14 E0 Y8 A8
13 28 E0 Y13 A13
14 29 E0 Y14 A14
15 6 HC32 (31 C1 (CRDW) OR REG_CRDUNLOCK1 OR /REG_CRDUNLOCK2) /WE
16 NC READY
17 VCC
18 VCC
19 39 E0 Y16 A16
20 30 E0 Y15 A15
21 27 E0 Y12 A12
22 13 E0 Y7 A7
23 12 E0 Y6 A6
24 11 E0 Y5 A5
25 9 E0 Y4 A4
26 8 E0 Y3 A3
27 7 E0 Y2 A2
28 6 E0 Y1 A1
29 5 E0 Y0 A0
30 6 G0 MCD0 D0
31 7 G0 MCD1 D1
32 8 G0 MCD2 D2
33 88 C1 IN26 (REG_STATUS_B bit 6) WP (Write Protect)
34 GND
Pin Goes to Signal name PC Card name
35 GND
36 73 C1 IN24 (REG_STATUS_B bit 4) /CD1 (Card Detect 1)
37 30 G0 MCD11 D11
38 43 G0 MCD12 D12
39 44 G0 MCD13 D13
40 45 G0 MCD14 D14
41 46 G0 MCD15 D15
42 7 /CE2
43 NC /VS1
44 NC /IORD
45 NC /IOWR
46 40 E0 Y17 A17
47 41 E0 Y18 A18
48 43 E0 Y19 A19
49 44 E0 Y20 A20
50 45 E0 Y21 A21
51 VCC
52 VCC
53 46 E0 Y22 A22
54 47 E0 Y23 A23
55 NC A24
56 NC A25
57 NC /VS2
58 NC RESET
59 NC /WAIT
60 NC Reserved
61 8 HC32 (REG_CRDREGSEL OR CRDO) /REG
62 NC BVD2
63 NC BVD1
64 27 G0 MCD8 D8
65 28 G0 MCD9 D9
66 29 G0 MCD10 D10
67 87 C1 IN25 (REG_STATUS_B bit 5) /CD2 (Card Detect 2)
68 GND