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we are able to see how this rare accessory, uses by only the following games looks like:
* Battle Stadium: Senbatsu Pro Yakyuu
* Armadillo
* J-League Fighting Soccer - The King of Ace Strikers
* Seiryaku Simulation - Inbou no Wakusei - Shancara
Battle Box consists of two serial 128 x 16bit EEPROM memories (TC89102) and two JK flip-flops to control them. While the logical layout of memory content seems to resemble some kind of simple "file system", so that it can be shared among different games, i'm still trying to understand how the communication physically looks like.
* OUT0 ($4016.D0) is directly to memories' clock
* memories' DO is connected to $4017.D4, so CPU gets inversion of the line (after passing thru 74368)
* flip flop's Q, wired to memories DI, toggles every time $4017 is read (and its inversion can be read back by $4017.D4) so CPU sees the same is on DI but looking how the 4017 read cycle looks like it turns out that CPU will see what was at the memory DI but at the end of this cycle, the value will be toggled (so in fact value read by $4017.D4 will be opposite of what will be at memory DI)
Code: Select all
M2 ______------_________
4017_CLK ------______---------
DI--------------[ B ][ not B ]
|
+-- CPU will read this