fixed eeprom documentation

source/docs/eeprom.txt

@@ -1,8 +1,89 @@
-This is the result of testing EEPROM support under Genesis Plus.
+Here are some notes about EEPROM emulation, which is used in a few Sega Genesis Cartridge as external Backup RAM.
-Following games use custom external RAM (serial EEPROM) for backup.
+
-It seems that different EEPROM Mapper have been used, depending upon companies.
+The protocol used to communicate (read/write) with serial EEPROM is explained below:
+
+
+1/ from 68000 cpu (MASTER), which is running the ROM program, each EEPROM can be managed using only two single lines:
+ - /SDA is the DATA line, used to send/receive data (READ/WRITE)
+ - /SCL is the CLOCK line used to synchronize the EEPROM cycles (WRITE ONLY)
+
+
+2/ each line is mapped in the 68000 address space at a specific address as one specific bit (see game mappers below) 
+and can be set at LOW (bit=0) or HIGH (bit=1) state.
+
+
+3/ each READ/WRITE operation must be initiated with a START condition and terminated by a STOP condition:
+ - START condition is set when /SDA is changed from HIGH to LOW while /SCL remaining HIGH 
+ - STOP condition is set when /SDA is changed from LOW to HIGH while /SCL remaining HIGH 
+
+
+4/ Following the START condition, the Master send one or more 8-bit word through the /SDA line to specify the address
+that must be read or write.
+Each bit write requires one clock cycle, managed by changing /SCL line state.
+There are 3 known EEPROM Modes, each one using different addressing protocol:
+
+ - Mode 1 EEPROMs (24C01 only) have a maximal size of 128bytes (7bits address) and need only one address word.
+ The 7 first bits specify the memory address to be read/write and the 8th bit indicates if the operation type (READ or WRITE)
+
+ - Mode 2 EEPROMs (24C01 to 24C16) can be linked together (8 slave devices max.), that means in fact one 24C16, two 24C08, four 24C04,
+ or eight 24C02/24C01, for a maximal size of 2 Kbytes (11bits address max.).
+ A first word is needed: the first 4 bits are fixed and, depending on the EEPROM size, the next 3bits specify the device address
+ and eventually the one (24C04), two (24C08) or three (24C16) upper bits of the memory address to be read/write.
+ As before, the 8th bit specifies the type of the operation (READ or WRITE)
+ Then a second word is needed to specify the eight lower bits of the address to be read/write. 
+
+ - Mode 3 EEPROMS (24C32 and more) work quite the Type 2 EEPROMS excepted that the maximal address size is 64 Kbytes (16bits address max.) 
+ The first word is like in the previous type, bits d3-d1 always specifying the slave device address (8 linked devices max.)
+ The second word specifies the upper bits of the address to be read/write.
+ A third word specifies the eight lower bits of the address to be read/write.
+
+ NOTE: In Mode2 and Mode3, before a READ operation, only the SLAVE ADDRESS WORD will be sent, the EEPROM contains an address counter
+       that maintains the address of the last word to be accessed (from a previous READ or WRITE operation)
+
+
+ 5/ Each time a 8bits word has been written (which requires eight clock cycles), the receiver (could be EEPROM or MASTER) send an acknowledge
+ to the sender by setting /SDA line LOW during the 9th cycle (ACK cycle).
+
+
+ 6/ After a WRITE SEQUENCE has been initiated, the MASTER will sent DATA as one or more sequences of 8bits words.
+ After each written word, the EEPROM must send a ACK and increment the address for the next data word to be written.
+ Word address will roll up to base address when maximal writepage size has been reached.
+ If the Master send a STOP condition, the WRITE operation ends.
+ Otherwise the WRITE operation continues to next address.
+ 
+
+ 7/ After a READ SEQUENCE has been initiated, the MASTER will read DATA as one or more sequence of 8bits words.
+ After each received word, the MASTER will send a ACK and the EEPROM will increment the address of the next data word to be read.
+ Word address will roll up to 0 when maximal memory size has been reached.
+ If the Master does not send a ACK during the 9th cycle, the READ operation ends and the EEPROM waits for STOP condition.
+ Otherwise, the READ operation continue to next address. 
+
+
+This is pretty how I emulate EEPROM access in Genesis Plus (see eeprom.c for technical details).
+Thanks a lot to 8bitWizard from Spriteminds.net forums which initially give indications about the various EEPROM types and mappers
+that can be found in Sega Genesis games.
+
+Here are some links to datasheets with should explain everything better than me and my crappy english ;)
+
+MODE1 (24C01 only):
+http://www.icmic.com/datasheets/X24C01.pdf
+
+MODE2 (24C01 - 24C16):
+http://www.atmel.com/dyn/resources/prod_documents/doc0180.pdf
+
+MODE3 (24C32 and more):
+http://www.phys.hawaii.edu/~bryce/component_data/24LC65-ISM.pdf
+
+
+Below are the Sega Genesis games that I found using serial EEPROM as external Backup RAM.
+I also give their specific caracteristics (mapper, size, ...), determined when testing my emulation code.
+
+
+
+EkeEke
+July 2007
+
 
-Eke~Eke - July 2007
 
 
 -------------------------------------------------------
@@ -19,11 +100,11 @@ header OK ($200001-$200001)
 TYPE: 8BITS WORD ADDRESS
 SIZE_MASK: 0xFF (24C02)
 PAGE_MASK: 0x03
-SDA_IN : 0x200000 (0)
+SDA_IN : 0x200000 (bit 0)
-SDA_OUT: 0x200000 (1)
+SDA_OUT: 0x200000 (bit 1)
-SCL : 0x200000 (1)
+SCL : 0x200000 (bit 1)
 
-Note: this game uses a different EEPROM mapper than other Acclaim games.
+NB: this game uses a different EEPROM mapper than any other Acclaim games.
 
 
 Blockbuster World Video Game Championship II (U)
@@ -35,12 +116,16 @@ header KO
 TYPE: TYPE: 8BITS WORD ADDRESS
 SIZE_MASK: 0xFF (24C02)
 PAGE_MASK: 0x03
-SDA_IN : 0x200001 (0)
+SDA_IN : 0x200001 (bit 0)
-SDA_OUT: 0x200001 (0)
+SDA_OUT: 0x200001 (bit 0)
-SCL : 0x200000 (0)
+SCL : 0x200000 (bit 0)
-
-Note: Rev 00 of the game has buggy eeprom support (incorrect data written), game backup only work with Rev01 version (released apparently in 2002, eight years later !)
 
+NB: Rev 00 of the game has buggy eeprom support and game backup does not seem to work fine, only Rev01
+version will correctly save game data.
+For history, Steve Snake, the author of Kega, one of the best Genesis emulator for Win32 platforms, is
+the one who originally developped this game.
+I assume that he released himself later some kind of patch to fix the backup support.
+(from the header informations, rev01 has been released in 2002, eight years after rev00 !)
 
 NFL Quarterback Club (JUE)
 -----------------------------
@@ -50,9 +135,9 @@ header OK ($200000-$200001)
 TYPE: TYPE: 8BITS WORD ADDRESS
 SIZE_MASK: 0xFF (24C02)
 PAGE_MASK: 0x03
-SDA_IN : 0x200001 (0)
+SDA_IN : 0x200001 (bit 0)
-SDA_OUT: 0x200001 (0)
+SDA_OUT: 0x200001 (bit 0)
-SCL : 0x200000 (0)
+SCL : 0x200000 (bit 0)
 
 
 NFL Quarterback Club 96 (UE)
@@ -63,9 +148,9 @@ header OK ($200000-$200001)
 TYPE: TYPE: 8BITS WORD ADDRESS
 SIZE_MASK: 0x7FF (24C16)
 PAGE_MASK: 0x07
-SDA_IN : 0x200001 (0)
+SDA_IN : 0x200001 (bit 0)
-SDA_OUT: 0x200001 (0)
+SDA_OUT: 0x200001 (bit 0)
-SCL : 0x200000 (0)
+SCL : 0x200000 (bit 0)
 
 
 College Slam (U)
@@ -76,9 +161,9 @@ header OK ($200001-$200001)
 TYPE: 16BITS WORD ADDRESS
 SIZE_MASK: 0x1FFF (24C64)
 PAGE_MASK: 0x07
-SDA_IN : 0x200001 (0)
+SDA_IN : 0x200001 (bit 0)
-SDA_OUT: 0x200001 (0)
+SDA_OUT: 0x200001 (bit 0)
-SCL : 0x200000 (0)
+SCL : 0x200000 (bit 0)
 
 
 Frank Thomas Big Hurt Baseball (UE)
@@ -89,9 +174,9 @@ header OK ($200000-$200001)
 TYPE: 16BITS WORD ADDRESS
 SIZE_MASK: 0x1FFF (24C64)
 PAGE_MASK: 0x07
-SDA_IN : 0x200001 (0)
+SDA_IN : 0x200001 (bit 0)
-SDA_OUT: 0x200001 (0)
+SDA_OUT: 0x200001 (bit 0)
-SCL : 0x200000 (0)
+SCL : 0x200000 (bit 0)
 
 
 
@@ -109,9 +194,9 @@ header OK ($200001-$200001)
 TYPE: 7BITS WORD ADDRESS
 SIZE_MASK: 0x7F (24C01)
 PAGE_MASK: 0x03
-SDA_IN : 0x200001 (0)
+SDA_IN : 0x200001 (bit 0)
-SDA_OUT: 0x200001 (0)
+SDA_OUT: 0x200001 (bit 0)
-SCL : 0x200001 (1)
+SCL : 0x200001 (bit 1)
 
 NOTE: the original version of Rockman Mega World (J) uses traditional SRAM, header gives $200000-$203FFF range
 the alternate version uses a 128bytes serial EEPROM (X24C01)
@@ -131,9 +216,9 @@ header KO
 TYPE: 7BITS WORD ADDRESS
 SIZE_MASK: 0x7F (24C01)
 PAGE_MASK: 0x03
-SDA_IN : 0x200000 (7)
+SDA_IN : 0x200000 (bit 7)
-SDA_OUT: 0x200000 (7)
+SDA_OUT: 0x200000 (bit 7)
-SCL : 0x200000 (6)
+SCL : 0x200000 (bit 6)
 
 
 Rings of Power (UE)
@@ -144,9 +229,9 @@ header KO
 TYPE: 7BITS WORD ADDRESS
 SIZE_MASK: 0x7F (24C01)
 PAGE_MASK: 0x03
-SDA_IN : 0x200000 (7)
+SDA_IN : 0x200000 (bit 7)
-SDA_OUT: 0x200000 (7)
+SDA_OUT: 0x200000 (bit 7)
-SCL : 0x200000 (6)
+SCL : 0x200000 (bit 6)
 
 
 
@@ -162,9 +247,9 @@ header OK ($200001-$200001)
 TYPE: 7BITS WORD ADDRESS
 SIZE_MASK: 0x7F (24C01)
 PAGE_MASK: 0x03
-SDA_IN : 0x200001 (0)
+SDA_IN : 0x200001 (bit 0)
-SDA_OUT: 0x200001 (0)
+SDA_OUT: 0x200001 (bit 0)
-SCL : 0x200001 (1)
+SCL : 0x200001 (bit 1)
 
 
 Greatest Heavyweights of the Ring (U)
@@ -179,9 +264,9 @@ header OK ($200001-$200001)
 TYPE: 7BITS WORD ADDRESS
 SIZE_MASK: 0x7F (24C01)
 PAGE_MASK: 0x03
-SDA_IN : 0x200001 (0)
+SDA_IN : 0x200001 (bit 0)
-SDA_OUT: 0x200001 (0)
+SDA_OUT: 0x200001 (bit 0)
-SCL : 0x200001 (1)
+SCL : 0x200001 (bit 1)
 
 
 Wonder Boy in Monster World (UE)
@@ -193,9 +278,9 @@ header OK ($200001-$200001)
 TYPE: 7BITS WORD ADDRESS
 SIZE_MASK: 0x7F (24C01)
 PAGE_MASK: 0x03
-SDA_IN : 0x200001 (0)
+SDA_IN : 0x200001 (bit 0)
-SDA_OUT: 0x200001 (0)
+SDA_OUT: 0x200001 (bit 0)
-SCL : 0x200001 (1)
+SCL : 0x200001 (bit 1)
 
 
 
@@ -211,12 +296,11 @@ header KO
 TYPE: TYPE: 8BITS WORD ADDRESS
 SIZE_MASK: 0x3FF (24C08)
 PAGE_MASK: 0x0F
-SDA_IN : 0x300000 (0)
+SDA_IN : 0x300000 (bit 0)
-SDA_OUT: 0x380001 (7)
+SDA_OUT: 0x380001 (bit 7)
-SCL : 0x300000 (1)
+SCL : 0x300000 (bit 1)
 
-Note: this game needs the EEPROM to be initially fullfilled with the string
+NB: this game needs the external RAM to be initialized with 0xFF otherwise it won't initialize memory with correct data.
-"PETETEST01234567" otherwise it won't initialize memory with correct data.
 
 
 Micro Machines Military (E) (J-Cart)
@@ -227,9 +311,9 @@ header KO
 TYPE: TYPE: 8BITS WORD ADDRESS
 SIZE_MASK: 0x3FF (24C08)
 PAGE_MASK: 0x0F
-SDA_IN : 0x300000 (0)
+SDA_IN : 0x300000 (bit 0)
-SDA_OUT: 0x380001 (7)
+SDA_OUT: 0x380001 (bit 7)
-SCL : 0x300000 (1)
+SCL : 0x300000 (bit 1)
 
 
 Micro Machines Turbo Tournament 96 (E) (J-Cart)
@@ -240,6 +324,6 @@ header KO
 TYPE: TYPE: 8BITS WORD ADDRESS
 SIZE_MASK: 0x7FF (24C16)
 PAGE_MASK: 0xF
-SDA_IN : 0x300000 (0)
+SDA_IN : 0x300000 (bit 0)
-SDA_OUT: 0x380001 (7)
+SDA_OUT: 0x380001 (bit 7)
-SCL : 0x300000 (1) 
+SCL : 0x300000 (bit 1) 

source/eeprom.c

@@ -1,3 +1,23 @@
+/****************************************************************************
+ *  Serial EEPROM support for Sega Genesis games
+ *
+ *  Copyright (C) 2007 EkeEKe
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ ***************************************************************************/
+
 #include "shared.h"
 #include "rominfo.h"
 

source/eeprom.h

@@ -1,4 +1,38 @@
+/****************************************************************************
+ *  Serial EEPROM support for Sega Genesis games
+ *
+ *  Copyright (C) 2007 EkeEKe
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ ***************************************************************************/
+
+typedef enum
+{
+	STAND_BY = 0,
+	WAIT_STOP,
+	GET_SLAVE_ADR,
+	GET_WORD_ADR_7BITS,
+	GET_WORD_ADR_HIGH,
+	GET_WORD_ADR_LOW,
+	WRITE_DATA,
+	READ_DATA,
+
+} T_EEPROM_STATE;
+
 /* this defines the type of EEPROM inside the game cartridge as Backup RAM
+ *
  * Here are some notes from 8BitWizard (http://www.spritesmind.net/_GenDev/forum):
  *
  * Mode 1 (7-bit) - the chip takes a single byte with a 7-bit memory address and a R/W bit (24C01)
@@ -15,43 +49,32 @@
 
 typedef struct
 {
-	uint8 address_bits;		/* number of bits needed to address the array: 7, 8 or 16 */
+	uint8 address_bits;		/* number of bits needed to address memory: 7, 8 or 16 */
-	uint16 size_mask;		/* size of the array (in bytes) - 1 */
+	uint16 size_mask;		/* depends on the max size of the memory (in bytes) */
-	uint16 pagewrite_mask;	/* maximal number of bytes that can be written in a single write cycle - 1*/
+	uint16 pagewrite_mask;	/* depends on the maximal number of bytes that can be written in a single write cycle */
-	uint32 sda_in_adr;		/* 68k address used by SDA_IN signal */
+	uint32 sda_in_adr;		/* 68000 memory address mapped to SDA_IN */
-	uint32 sda_out_adr;		/* 68k address used by SDA_OUT signal  */
+	uint32 sda_out_adr;		/* 68000 memory address mapped to SDA_OUT */
-	uint32 scl_adr;			/* address used by SCL signal  */
+	uint32 scl_adr;			/* 68000 memory address mapped to SCL */
-	uint8 sda_in_bit;		/* position of the SDA_IN bit */
+	uint8 sda_in_bit;		/* bit offset for SDA_IN */
-	uint8 sda_out_bit;		/* position of the SDA_OUT bit */
+	uint8 sda_out_bit;		/* bit offset for SDA_OUT */
-	uint8 scl_bit;			/* position of the SCL bit */
+	uint8 scl_bit;			/* bit offset for SCL */
 
 } T_EEPROM_TYPE;
 
-typedef enum
-{
-	STAND_BY = 0,
-	WAIT_STOP,
-	GET_SLAVE_ADR,
-	GET_WORD_ADR_7BITS,
-	GET_WORD_ADR_HIGH,
-	GET_WORD_ADR_LOW,
-	WRITE_DATA,
-	READ_DATA,
-
-} T_EEPROM_STATE;
 
 typedef struct
 {
-	uint8 sda;
+	uint8 sda;				/* current /SDA line state */
-	uint8 scl;
+	uint8 scl;				/* current /SCL line state */
-	uint8 old_sda;
+	uint8 old_sda;			/* previous /SDA line state */
-	uint8 old_scl;
+	uint8 old_scl;			/* previous /SCL line state */
-	uint8 cycles;
+	uint8 cycles;			/* current operation cycle number (0-9) */
-	uint8 rw;
+	uint8 rw;				/* operation type (1:READ, 0:WRITE) */
-	uint16 slave_mask;
+	uint16 slave_mask;		/* device address (shifted by the memory address width)*/
-	uint16 word_address;
+	uint16 word_address;	/* memory address */
-	T_EEPROM_STATE state;
+	T_EEPROM_STATE state;	/* current operation state */
-	T_EEPROM_TYPE type;
+	T_EEPROM_TYPE type;		/* EEPROM characteristics for this game */
+
 } T_EEPROM;
 
 /* global variables */

source/input.c

@@ -16,7 +16,8 @@
     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
 /*
-	NGC port (June 2007): Added various Peripherals emulation (Eke-Eke)
+	02/2007: fixed 6BUTTONS gamepad emulation (Eke-Eke)
+	06/2007: Added TEAMPLAYER/4WAYPLAY/MENACER emulation (Eke-Eke)
 */
 
 #include "shared.h"

source/ngc/loadrom.c

@@ -83,6 +83,7 @@ void genesis_set_region ()
  * set specific timings for some games
  */
  extern uint8 alttiming;
+ extern uint8 vdptiming;
  extern uint8 sys_type[2];
 
  void detect_game()

source/state.c

@@ -17,7 +17,9 @@
  *  along with this program; if not, write to the Free Software
  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  *
- *  STATE MANAGER
+ *
+ *  Freeze State support (added by EkeEke for the Gamecube's port - Feb,2007)
+ *
  ***************************************************************************/
 #include "shared.h"
 

source/state.h

@@ -17,7 +17,9 @@
  *  along with this program; if not, write to the Free Software
  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  *
- *  STATE MANAGER
+ *
+ *  Freeze State support (added by EkeEke for the Gamecube's port - Feb,2007)
+ *
  ***************************************************************************/
 #ifndef _STATE_H_
 #define _STATE_H_