Revision as of 00:35, 9 March 2017

SRAM memory card, showing the SRAM chip and voltage detection circuit. Picture by HPMAN

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.

Address	Name	Size	Description
$0~$9		10 bytes	Zeros or "SNK ROM " (development unit ?) For 16 bits "doubled" cards, $6 is set to $0001
$A	CARD_SIZE	word	Card capacity
$C		byte	0
$D	CARD_FAT_1_CHKSUM	byte	Checksum of FAT 1
$E	CARD_FAT_2_CHKSUM	byte	Checksum of FAT 2
$F	CARD_USERNAME_AVAILABLE	byte	0 : Username available, !0 : Username unavailable
$10	CARD_USERNAME	16 bytes	Card holder's 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 the system that formated the card, 0 = Japan, 1 = USA, 2 = Europe

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 REG_CRDUNLOCK1 is 0 and REG_CRDUNLOCK2 is 1
The WP (Write Protect) pin is read through bit 6 of REG_STATUS_B
CD1 (Card Detect 1) is read through bit 4 of REG_STATUS_B
CD2 (Card Detect 2) is read through bit 5 of REG_STATUS_B
Attribute memory is selected if REG_CRDREGSEL is 1

Card pinout (top)

Pin #	Name	Signal	Description	Goes to
1	GND
2	D3	CDD3	Data bus	NEO-G0
3	D4	CDD4
4	D5	CDD5
5	D6	CDD6
6	D7	CDD7
7	/CE1	CRDC	Chip enable 1	NEO-C1
8	A10	CDA10	Address	NEO-E0
9	/OE	CRDO	Output enable	NEO-C1
10	A11	CDA11	Address bus	NEO-E0
11	A9	CDA9
12	A8	CDA8
13	A13	CDA13
14	A14	CDA14
15	/WE		Write enable	HC32
16	/BUSY	Low when card is busy	Not used
17	VCC
18	VPP
19	A16	CDA16	Address bus	NEO-E0
20	A15	CDA15
21	A12	CDA12
22	A7	CDA7
23	A6	CDA6
24	A5	CDA5
25	A4	CDA4
26	A3	CDA3
27	A2	CDA2
28	A1	CDA1
29	A0	CDA0
30	D0	CDD0	Data bus	NEO-G0
31	D1	CDD1
32	D2	CDD2
33	WP	WP	High if card is write-protected	NEO-C1
34	GND

Card pinout (bottom)

Pin #	Name	Signal	Description	Goes to
35	GND
36	/CD1	CD1	Card detect	NEO-C1
37	D11	CDD11	Data bus	NEO-G0
38	D12	CDD12
39	D13	CDD13
40	D14	CDD14
41	D15	CDD15
42	/CE2	CRDC	Chip enable 2	NEO-C1
43	/VS1	Not used
44	/IORD
45	/IOWR
46	A17	CDA17	Address bus	NEO-E0
47	A18	CDA18
48	A19	CDA19
49	A20	CDA20
50	A21	CDA21
51	VCC
52	VCC
53	A22	CDA22	Address bus	NEO-E0
54	A23	CDA23	Address bus	NEO-E0
55	A24	Not used
56	A25
57	/VS2
58	RESET
59	/WAIT
60	NC	Reserved
61	/REG		Select attribute memory	HC32
62	BVD2	Battery voltage detect	Not used
63	BVD1	Battery voltage detect	Not used
64	D8	CDD8	Data bus	NEO-G0
65	D9	CDD9
66	D10	CDD10
67	/CD2	CD2	Card detect	NEO-C1
68	GND

@@ Line 1: / Line 1: @@
-JEIDA V3 memory cards used in AES and some [[MVS hardware|MVS systems]] to store game saves and/or high scores. The original SNK card could only hold 2KiB of data.
+[[File:snkmemcard.jpg|thumb|SRAM memory card, showing the SRAM chip and voltage detection circuit. Picture by [[User:HPMAN|HPMAN]]]]
-[[File:snkmemcard.jpg|thumb|Picture by [[User:HPMAN|HPMAN]]]]
+The NeoGeo (AES and some [[MVS hardware|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 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.
-The SP-S2 [[system ROM]] can handle memory cards up to 16KiB
+See the [[CARD]] call description for memory card operations.
-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).
+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 the data here are for all the card, it's just a matter on how to read the data between different type of card.
+All cards use the same format regardless of capacity.
-The internal card data are splitted into 5 regions.
+The data is split into 5 regions:
 ==Header==
-Always $80 bytes.
+Always 128 bytes.
 {| class="regdef"
@@ Line 32: / Line 28: @@
 |
 |10 bytes
-|Zero or "SNK ROM " (Development unit I think)
+|Zeros or "SNK ROM " (development unit ?)
-For 16bits doubled card, $6 is set to $0001
+For 16 bits "doubled" cards, $6 is set to $0001
 |-
 |$A
 |CARD_SIZE
 |word
-|Size of the memcard
+|Card capacity
 |-
 |$C
@@ Line 49: / Line 45: @@
 |CARD_FAT_1_CHKSUM
 |byte
-|Checksum of the FAT 1
+|Checksum of FAT 1
 |-
 |$E
 |CARD_FAT_2_CHKSUM
 |byte
-|Checksum of the FAT 2
+|Checksum of FAT 2
 |-
 |$F
@@ Line 64: / Line 60: @@
 |CARD_USERNAME
 |16 bytes
-|Card holder username
+|Card holder's 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
+|$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
+|Region of the system 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.
+List of saves of 32, 64, 96, 128, 160, 192, 224 or 256 entries. The size depends on the card's capacity.
-Each entry have this format :
+Each entry has the following format:
 {| class="regdef"
@@ Line 90: / Line 86: @@
 |$0
 |byte
-|Game Sub number (CARD_SUB), 0 to 15. $FF if entry is free
+|Save sub number (CARD_SUB), 0 to 15. $FF if entry is free.
 |-
 |$1
 |word
-|Game NGH number
+|Game's [[NGH number]]
 |-
 |$3
@@ Line 103: / Line 99: @@
 ==FAT 1==
-List of used blocks. Size depends on card size, it can hold 64, 128 192 or 256 entries.
+List of used blocks, of 64, 128, 192, or 256 entries. The size depends on the card's capacity.
-* $02 is a BIOS reserved block
+* $02 is a block reservd by the system ROM
-* $01 is a game used block
+* $01 is a block used by a game
 * $00 is a free block
@@ Line 114: / Line 110: @@
 ==Game Data==
-Normally 64 bytes but maybe some games use more that one block ?
+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=
-The first 20 bytes are the data title (generally the game name + the stage name).
+* Write is enabled if {{Reg|REG_CRDUNLOCK1}} is 0 and {{Reg|REG_CRDUNLOCK2}} is 1
+* The WP (Write Protect) pin is read through bit 6 of {{Reg|REG_STATUS_B}}
+* CD1 (Card Detect 1) is read through bit 4 of {{Reg|REG_STATUS_B}}
+* CD2 (Card Detect 2) is read through bit 5 of {{Reg|REG_STATUS_B}}
+* Attribute memory is selected if {{Reg|REG_CRDREGSEL}} is 1
 =Card pinout (top)=

Memory card: Difference between revisions