22.09.2014 krikzz.com
extended_ssf-v2 mapper supported begins from OS v10.
Please check ssf-ex-sample for details

Extensions:
1) Mapper allow to use up to 16 or 32 Mbyte of memory (Depends from installed memory chip)
2) Write acces to ROM memory. ROM memory can be used as RAM
3) First bank can be switched like any other bank
4) Oboard Led control
5) Hardware division and multiplication
6) Access to USB IO
7) Access to SD IO

registers:

Math registers for division or multiplication. Can operate with 16 or 32 bit number.
0xA130D0 MATH_ARG_HI read/write
0xA130D2 MATH_ARG_LO read/write
0xA130D4 MATH_MUL_HI write only
0xA130D6 MATH_MUL_LO write only
0xA130D8 MATH_DIV_HI write only
0xA130DA MATH_DIV_LO write only
 Mul result = MATH_ARG * MATH_MUL
 Div result = MATH_ARG / MATH_DIV
 First should be written MATH_ARG, then MATH_MUL or MATH_DIV. Read result from MATH_ARG. Check ssf-ex-sample for more details

SD card
0xA130E0 [DDDDDDDD dddddddd]  read/write
 d lo data bits
 D hi data bits (active only in 16bit mode)
 
USB IO
0xA130E2 [........ DDDDDDDD] read/write
 D data bits

IO status
0xA130E4 [.C...... .....RWS] read only
 S SPI controller ready
 W USB fifo ready to write
 R USB fifo ready to read
 C SD card type. 0=SD, 1=SDHC

IO config
0xA130E6 [........ .....AMS] write only
 S Directly connected to SD card chip select
 M 16bit SPI mode
 A Auto read. Allow to read data from SPI without writing. Should be used in pair with 16bit mode
 
Mapper control
0xA130F0 [PXWL.... ...RRRRR] write only
  P is a protection bit. Bit P always should be set for any manipulations with reg 0xA130F0 (0=access to register is deny, 1=new value can be loaded)
  X 32x mode. Should be set in case if game use 32x
  W ROM memory write protect (0=not writable, 1=writable)
  L LED (0=off, 1=on)
  R 512Kbyte bank
 

0xA130F2-0xA130FE [........ ...RRRRR] write only
   R 512Kbyte bank

Mapper will be activated in case if ROM header contains "SEGA SSF" string, instead of standard "SEGA GENESIS" string.

Banks 30-31 used by OS, not recommended to touch them, otherwise OS may not boot after reset, in this case OS will start only after cold start.

Bank 28 can be used for saves. First 32Kbyte of this bank will be copied to SD card