Famicom/NES mapper Documents Vol.1

@Nintendo

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Famicom

 · 4 years ago

 
                    Famicom/NES mapper Documents Vol.1 
                           Version 0.2b (1997/6/12) 
                          Focus on FFE mapper Type I 
                                 FanWen Yang 

FFE mapper !! Type I,II   aka "#6" in iNES .. 
============================================================================= 
   I/O ADDR     FUNTION              IN 
    42FC        PG  WE 
    42FD        HV  WE 
    42FE,bit4   PG  SW 
    42FF,bit4   HV  SW 

    43FE        8,A,C,E  4M          <-write any byte to it to set this mode 

 
=============================================================================== 

    4500        CONFIG             (42F*) BZ BT 
    4501        IRQ OFF            (43F*) 
    4502        CL 
    4503        CH , COUNTER SW 

========================================================================= 
Config the FFE hardware !!!!!!! 

 
       4500W        REM 
 7 6 5 4 3 2 1 0 
 0 0              LOAD  MODE    <----- famicom disk system  game !! 
 1 0              CARD  MODE    <----- run the carts on the ffe unit 
 0 1              EXEC  MODE    <----- exec loaded game . 
     X X          6000 - 7FFF  BANK <-----  SRAM present or Not 
         X        SW PIN 
           X X X  PPU  MODE 
           0 1 0  *MODE (256K) 
           1 0 1  2M , VRAM EXT 
           1 1 1  2M 

============================================================================== 
Config the FFE hardware !!!!!!! 

  CPU  MODE     BIT             REM 

            7 6 5 4 3 2 1 0 

  43FE      C C C C C C P P 8,A,C,E (4M) ----+------> F4  series 

 
  *MODE      8000W , 43FFW      REM 
-------------------------------------------------------------- 
  42FXW      7 6 5 4 3 2 1 0  CPU + PPU 
    20           C C C C P P   2M + 256K <-------- in iNES this is 90% mapper #6 
    40               C C C C   2M + 64K  <-------- in iNES this is mapper #2 
    60           P P C C C C   2M + 256K <-------- in iNES this is 10% mapper #6 
    80           C C     P P   1M + 256K <-------- in iNES this is mapper #8 
                                         F3 series 

IRQ : 
     (increasing) 
     when the value of counter exceed $FFFF and will reset counter to $0000 
     something like Namcot mapper 's counter but 
     Namcot one generated IRQ when value of counter = $FFFF and no reset! 
     but FFE one generated IRQ when value of counter =$0000 and reset ! 
=============================================================================== 
Trainer: 
        either loaded into $7000 (most) or $5D00(few) .totally 512byte ! 
        but all FFE rom image are modified :( ...if without trainer mean 
        modified less than with trainer .. 

   Trainer Structure 
                 7000 Jump 1 <--- NMI 
                 7003 Jump 2 <--- Seting game (maybe do a check if this is 
                                  FFE unit ,write a address and read from it) 
                 7006 Jump 3 <--- H.V or others 

=============================================================================== 

!! HOW F4 trained work ? !! (aka "4M 8/A/C/E mode" ) 
most F4 series are 2M+64K RAM ,2M+256K(type 1 ) ,2M +256 K (type 2) 

!!2M + 64 K Ram .it's very easy  <------ mapper #2 in iNES 
8000-9FFF: via 8000 
A000-BFFF: via A000 
C000-DFFF: via C000 
E000-FFFF: via E000 

 
$8000,A000,C000,E000 

 bit7-bit4|bit3-bit0 
  no used | CPU bank switching 
------------------------------------------------------------------------ 
!!2M +256K Ram type 1 (few F4 trained series) <----- 10 % mapper #6 in iNES 

$8000,A000,C000,E000 
 bit7-bit6|bit5-bit4|bit3-bit0 
 no used     PPU      CPU 
------------------------------------------------------------------------ 
2M +256K Ram type 2   (most F4 trained series) <----- 90 % mapper #6 in iNES 

$8000,A000,C000,E000 
 bit7-bit6|bit5-bit2|bit1-bit0 
  no used     CPU      PPU 
------------------------------------------------------------------------- 
what is PPU switch in 2M+256K ? 
FFE has 256 K PPU RAM and spilt to 4 page ... 
4 X 64 K ...they can switch it and choose which one will be on the 0-1FFF ! 

for example. 
  trainer move date to first page of thoes .. then now .. ready to play 
  when you played level one of game .. maybe those date of first page 
  not enough ..trainer will move all need date to 2nd page of and let page 2 on 
  .and 1st page date are not disapear .. just off of screen ..:P ,now you 
  played 2 level of game ..maybe just need some small change to first page . 
  then trainer switch back to first page and move some data into it .. 
  this is what it works !!!!!! 

============================================================================= 

This is some info  of FFE mapper ... just part of FFE mapper ... 
FFE unit is so complex ... this will be usefully to improve mapper #6 
If you have any Question of it ,you can mail Me ............. 
No more Rom Request .PLZ 
join irc to contact with me interactive !!!! 
#emu,#snes,#emulate  my nickname _FanWen_ 
OR email address : yangfanw@ms4.hinet.net 

Note : All material is written by Me , so if you want to pull it into public 
       PLZ keep the origianl text .. no modified !!!!!!!