Update README.md

1 files changed, 66 insertions, 2 deletions

diff --git a/sd/README.md b/sd/README.md
index 32b9060..cf55cbc 100644
--- a/sd/README.md
+++ b/sd/README.md
@@ -39,7 +39,7 @@ A172,24,48
 checksum, size in Mbit, number of banks (lorom needs twice as many banks as hirom for the same rom size)  
 
 #### hirom64.map  
-This is a Nintendo Power mapping file that changes the mapping to a single 4MB HiRom game with 64Kbit/8KByte save. The first byte is used to specify the mapping.  
+This is a Nintendo Power SF Memory mapping file that changes the mapping to a single 4MB HiRom game with 64Kbit/8KByte save. The first byte is used to specify the mapping.  
 
 Bit0-1 SRAM Size (0=2K, 1=8K, 2=32K, 3=None) ;ie. 2K SHL (N*2)  
 Bit2-4 ROM Size (0=512K, 2=1.5M, 5=3M, 7=4M) ;ie. 512K*(N+1)  
@@ -55,7 +55,7 @@ Example:
 01 -> 8K  
 
 #### lorom256.map  
-This is a Nintendo Power mapping file that changes the mapping to a single 4MB LoRom game with 256Kbit/32 KByte save.  
+This is a Nintendo Power SF Memory mapping file that changes the mapping to a single 4MB LoRom game with 256Kbit/32 KByte save.  
 
 Example:  
 0x1e = 0b 00 0 111 10  
@@ -63,3 +63,67 @@ Example:
 0  
 0b111 -> 7 -> 4M  
 0x10 -> 2 ->32k  
+
+#### mbc5.map
+This is a Nintendo Power GB Memory mapping file that changes the mapping to a single 1MB MBC5 game with 32 KByte save.  
+
+GB Mapping Info (by skaman)   
+Entries start at 0x0 divided into 3 Byte segments   
+   
+For example, let's look at the start of the mapping for a multi-game cart:     
+A8 00 00 71 04 00 48 94 04 separates into   
+A8 00 00 MENU    
+71 04 00 GAME 1   
+48 94 04 GAME 2   
+   
+Byte 00 of each entry contains the MBC Type, ROM Size, and SRAM Size (start).    
+SRAM Size is 3 bits across Byte 00 and Byte 01.   
+     MBC SZE SRAM    
+A8 = 101 010 00  0 MBC5, size 2 = 128KB   
+71 = 011 100 01  0 MBC3, size 4 = 512KB, SRAM 8KB   
+48 = 010 010 00  1 MBC2, size 2 = 128KB, SRAM MBC2   
+   
+Byte 00: 1st 3 Bits = MBC Type   
+        000 = MBC0   
+        001 = MBC1   
+        010 = MBC2   
+        011 = MBC3   
+        101 = MBC5   
+    
+Byte 00: 2nd 3 Bits = ROM Size (minimum size is 128KB due to block size)   
+        010 = Size 2 - 128KB   
+        011 = Size 3 - 256KB   
+        100 = Size 4 - 512KB   
+        101 = Size 5 - 1MB   
+   
+Byte 00: Last 2 Bits (bit1..bit0) + Byte 01: 1st Bit (bit7) = SRAM Size   
+        00 0 = NONE   
+        00 1 = SRAM MBC2    
+        01 0 = SRAM 8KB  
+        01 1 = SRAM 32KB   
+   
+Byte 01 contains the SRAM Size (end) and ROM Block in the Flash.   
+ROM Blocks are 128KB (8 total)   
+Byte 01: Last 7 Bits (bit6..bit0) = ROM Block   
+			00 = ROM Block 0  start offset 0KB   
+			04 = ROM Block 1  start offset 128KB   
+			08 = ROM Block 2  start offset 256KB   
+			0C = ROM Block 3  start offset 384KB   
+			10 = ROM Block 4  start offset 512KB   
+			14 = ROM Block 5  start offset 640KB   
+			18 = ROM Block 6  start offset 768KB   
+			1C = ROM Block 7  start offset 896KB   
+   
+Byte 02 contains the RAM Block in the SRAM.   
+RAM Blocks are 8KB (16 total)   
+Byte 02: RAM Block:       
+			00 = RAM Block 0  start offset 0KB   
+			04 = RAM Block 1  start offset 8KB   
+			08 = RAM Block 2  start offset 16KB   
+			0C = RAM Block 3  start offset 24KB			   
+			and so on until RAM Block 15.   
+   
+Going back to our example cart:   
+A8 00 00 MENU:  MBC5, size 2 = 128KB, ROM Block 0, RAM Block 0 (Ignored since SRAM is 000)   
+71 04 00 GAME 1:  MBC3, size 4 = 512KB, SRAM 8KB, ROM Block 1, RAM Block 0   
+48 94 04 GAME 2:  MBC2, size 2 = 128KB, SRAM MBC2, ROM Block 5, RAM Block 1