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PostPosted: Thu Mar 13, 2014 5:23 pm 
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I would like to update the cartridge connector page (http://wiki.nesdev.com/w/index.php/Cartridge_connector) with signal directions. Here is my initial cut at it...

Code:
              -------
      +5V -- |36   72| -- GND
 CIC toMB -> |35   71| -> CIC CLK
CIC toPak <- |34   70| -> CIC RST
   CHR D3 <> |33   69| <> CHR D4
   CHR D2 <> |32   68| <> CHR D5
   CHR D1 <> |31   67| <> CHR D6
   CHR D0 <> |30   66| <> CHR D7
   CHR A0 <- |29   65| -> CHR A13
   CHR A1 <- |28   64| -> CHR A12
   CHR A2 <- |27   63| -> CHR A10
   CHR A3 <- |26   62| -> CHR A11
   CHR A4 <- |25   61| -> CHR A9
   CHR A5 <- |24   60| -> CHR A8
   CHR A6 <- |23   59| -> CHR A7
CIRAM A10 -> |22   58| -> CHR /A13
  CHR /RD <- |21   57| <- CIRAM /CE
    EXP 4    |20   56| -> CHR /WR
    EXP 3    |19   55|    EXP 5
    EXP 2    |18   54|    EXP 6
    EXP 1    |17   53|    EXP 7
    EXP 0    |16   52|    EXP 8
     /IRQ -> |15   51|    EXP 9
  PRG R/W <- |14   50| -> PRG /CE (/A15 + /M2)
   PRG A0 <- |13   49| <> PRG D0
   PRG A1 <- |12   48| <> PRG D1
   PRG A2 <- |11   47| <> PRG D2
   PRG A3 <- |10   46| <> PRG D3
   PRG A4 <- |09   45| <> PRG D4
   PRG A5 <- |08   44| <> PRG D5
   PRG A6 <- |07   43| <> PRG D6
   PRG A7 <- |06   42| <> PRG D7
   PRG A8 <- |05   41| -> PRG A14                   
   PRG A9 <- |04   40| -> PRG A13
  PRG A10 <- |03   39| -> PRG A12
  PRG A11 <- |02   38| -> M2
      GND -- |01   37| -> SYSTEM CLK
              -------
             
CONN -> PIN NAME   Output to cartridge
CONN <- PIN NAME   Input from cartridge


Would love some feedback.


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PostPosted: Thu Mar 13, 2014 5:43 pm 
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LGTM. Should probably update both the FC and NES pinouts at the same time.

Do you want to update the page or shall I?


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PostPosted: Thu Mar 13, 2014 7:54 pm 
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I don't know if it was ever used as such, but the /IRQ line could also be considered bidirectional between the cart and EXP port (and the only such pin on Famicom).


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PostPosted: Thu Mar 13, 2014 8:18 pm 
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I like the idea, though I'm not sure I like the terminology. I think "direction" might imply some undesirable things, and the arrows feel ambiguous to me.

What if instead you called the various pin types:

1. controlled by NES
2. controlled by cartridge
3. controlled by either (or both, if bus conflict)

I dunno what I'd suggested for symbols, maybe arrows is okay, but it's confusing to me what they mean to represent. Do they point at the device that controls the line, or the device that is controlled by the line? These are questions that should be resolved with text accompanying the diagram or otherwise. (For reference: the cartridge card-edge would be inserted down into the middle of the diagram with the board sticking up out of the screen.)


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PostPosted: Thu Mar 13, 2014 8:28 pm 
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I borrowed the arrows from the CPU pin out (http://wiki.nesdev.com/w/index.php/CPU_ ... escription) and PPU pin outs (http://wiki.nesdev.com/w/index.php/PPU_ ... escription).

I agree, they can be a bit confusing but with a key describing them it should be better than nothing.


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PostPosted: Thu Mar 13, 2014 9:20 pm 
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If you're matching with those diagrams you linked, shouldn't the PRG/CHR A lines point "in" to the cartridge, not "out"? They came "out" of the CPU, they should go "in" to the cart, right?


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PostPosted: Fri Mar 14, 2014 5:41 am 
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My arrows are from the perspective of the NES motherboard not the cartridge. The reason I chose the MB side is because it is the only device of the pair to have all the connections "hooked up" all the time. For example some cartridges don't have a CIC chip so those would technically be NC.


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PostPosted: Fri Mar 14, 2014 7:50 am 
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I don't understand what you mean by the perspective of the motherboard. The motherboard is just a host of the lines being diagrammed. This is a diagram of the connector, looking straight into the connector. You have a description that says "output to cartridge" and then the arrow points away from the cartridge slot, and I don't understand why you would label it this way.

It's also opposite to the other diagrams you linked for comparison. These things should correspond, if it comes "out" of the CPU, it goes "in" to the cartridge. Do you understand what I'm saying? The two diagrams put together should look like:

[ cartridge connector ] <- PRG A5 <- [ CPU ]

But what you've done looks like:

[ cartridge connector ] -> PRG A5 <- [ CPU ]


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PostPosted: Fri Mar 14, 2014 8:09 am 
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Ah I see what you're saying. I'm thinking in terms of the other side of the connector where the connector connects to the cart not where the connector connects to the motherboard. I went ahead and changed the directions based on your advice.

I would love to fill in the CIC pins and EXP pins but I'm not sure what to fill them in with. If you have any insight into this it would be great.


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PostPosted: Fri Mar 14, 2014 8:30 am 
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The EXP pins aren't normally connected to anything. Any connection there is between something custom at both ends of the line. Maybe just -- or xx or the space that's already there for disconnected?

Hmm, I noticed you've used -- for 5V and Ground but I think both of these should be arrows pointing in to the connector. They're both controlled externally to the cartridge, so aren't they an input? I suppose they're fixed signals, no information going in or out, I dunno, depends on point of view maybe. Perhaps a special symbol is okay for them instead of an input arrow.

EXP 6 is commonly used by the PowerPak for expansion audio (requiring the NES end of the line to be tied into the audio circuit), and I believe EXP 9 is sometimes used for the same purpose on top loaders. There's a few other EXP uses listed on the connector page. It's probably fine to diagram them all as disconnected. Someone who has done a custom mod will know what's connected to them anyway.

I don't know much about the CIC circuit. Perhaps you can get the needed information here? http://wiki.nesdev.com/w/index.php/CIC_ ... hip_pinout


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PostPosted: Fri Mar 14, 2014 9:14 am 
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I personally like labeling the cart edge busses as "PPU" and "CPU" instead of "CHR" and "PRG". It's more compatible with how mapper chip pinouts are typically labeled. CHR is really a misnomer here anyway because that bus carries both CHR and NT.


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PostPosted: Fri Mar 14, 2014 10:15 am 
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rainwarrior wrote:
Hmm, I noticed you've used -- for 5V and Ground but I think both of these should be arrows pointing in to the connector. They're both controlled externally to the cartridge, so aren't they an input? I suppose they're fixed signals, no information going in or out, I dunno, depends on point of view maybe. Perhaps a special symbol is okay for them instead of an input arrow.
Convention is that power rails aren't considered to be "inputs" nor "outputs", hence why I used -- elsewiki.
Quote:
I don't know much about the CIC circuit.
CIC toPak is the same direction as PPU A10. CIC to toMB is the same direction as CIRAM A10. (I've already updated the wiki to match)

I renamed the CIC data signals because "in" and "out" are the pins of the CIC itself, and they don't change from master to slave. So those names don't really describe the routing of the signal across the connector.


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PostPosted: Fri Mar 14, 2014 11:31 am 
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I also advocate the "controlled by NES" and "controlled by cart" terminologies.
"Input" and "output" are extremely ambiguous, as an input form one side is an output from the other side. This can end up being more confusing than what it looks like at 1st.


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PostPosted: Fri Mar 14, 2014 3:27 pm 
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Yeah, that's basically the same problem with signals like TX/RX. When messing with UARTs (RS-232...) I end up using a scope to verify signal direction, you just don't know if it's from a DCE or a DTE standpoint. How much do I love how SPI signals are named: MOSI (Master In, Slave Out) and MISO, wow much clear so nice much easy.

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PostPosted: Fri Mar 14, 2014 9:44 pm 
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入出力表記のの追加はわかりやすくなりいいと思います。しかし、PRG/CHRバスの表記方法は時代遅れと感じています。

私のように memory controller IC (mapper IC) の配線を調べる立場にとって、 CPU/PPU から直接出ているバス全てを PRG/CHR と表記すると混乱だらけになる。この表記方法には否定的だ。私はバスを理解するまで、このような曖昧な表記方法のおかげで理解がおそかった。

I'm a position to examine the wiring of mapper IC. CPU/PPU buses are combined as PRG/CHR, which naming makes many confusion. I do not recommend this.


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