help for the pin out of the NES JALECO-JF-10

help for the pin out of the NES JALECO-JF-10
by tbpbird on 2018-11-09 (#228685)

I would like to make a repro of Urusei .
I cannot find the pin out of JALECO-JF-10.

Both PRG and CHR are 64k ( m27c512 ) DIP 14

I will use the original famicom japanese game to do the mod.

The boards has 2 time DIP 14 maskrom.

Pretty sure it can be a straight fit in without re-wiring anything,

Does anyone has info please ?

i would like to be sure before i solder them in

thank you

Re: help for the pin out of the NES JALECO-JF-10
by Fisher on 2018-11-12 (#228762)

Hello and welcome to NESDev!
AFAIK this board uses discrete logic ICs, with a 74HC139 and a 74HC74.
I'm not sure how they connect to the ROMs, can someone please trace the connections?

Re: help for the pin out of the NES JALECO-JF-10
by Fisher on 2018-11-13 (#228839)

Let me see if I understood this mapper:

If A13=1, A14=1, /ROMSEL=0 and R/W=1 the PRG bits D0 and D1 are latched on the flip-flop that controls CHR A13 and A14 lines.

Is it correct?

Re: help for the pin out of the NES JALECO-JF-10
by Fisher on 2018-11-14 (#228870)

I tried to trace the circuit and ended with this incomplete (and badly drawn) schematic:

Code:

                           
           +--CPU A13        ?   M2?
 +-----+   |  +--CPU A14  CPU R/W |  +--/ROMSEL
 |   __|?__|__|___          ___|__|__|___
 |  | /EN  A  B   |        | /EN  A  B   |  
 |  |             |        |             | 74HC139
 |  | Y0 Y1 Y2 Y3 |        | Y0 Y1 Y2 Y3 |
 |   -------------          ------------- 
 |    ?  ?  ?  |             ?  ?  ?  |?
 +-------------|----------------------+
               +----+                 
              ---   \ 
      1N4148? \ /   / 1K
             -----  \
          22pf |    | 
    GND----||--+----+
               |
      +--------+---------+
VCC---|-------+----------|-------+
      |    ___|___       |    ___|___
      |   |  CLR  |      |   |  CLR  |    
      +--->CK   /Q|      +--->CK   /Q|
        +-|D     Q|-+      +-|D     Q|-+   74HC74
        | |  PRE  | |      | |  PRE  | |
        |  -------  |      |  -------  |
     PRG D1   | CHR A13  PRG D2  |  CHR A14 
              +------------------+
              |      
             VCC          

I'm not sure, but the 2nd decoder of the 74HC139 probably has the A input pulled high, low or is plugged together on the B input.
Depending of the configuration I cited above one of the outputs should be connected to the /EN pin of the first decoder, wich enables the flip flop latch to trigger its outputs based on the data input.
I'm not sure if the PRE pins should be floating as they are.

I also may be totally wrong on my assumptions...
Can someone please correct me and fill the blanks?
Since I never had a board like this I'm just looking at pictures.

If the OP can check this out that would be a big help!
Thanks in advance.

Edit: Filled some blanks. The PRE pins seem to be pulled high.
Not sure if it's correct.

Re: help for the pin out of the NES JALECO-JF-10
by Fisher on 2018-11-15 (#228930)

A better drawn schematics:

Attachment:

File comment: Drawn with Eagle

Mapper 87.png [ 8.72 KiB | Viewed 7182 times ]

Still have the same doubts. :oops:

Hope the OP or someone else can solve them.

Re: help for the pin out of the NES JALECO-JF-10
by tbpbird on 2018-11-15 (#228946)

Hi thanks for the help, i will help you once i get the actual donor cart, should be next week.
Ill let you know where those traces go
thank you for your help

Re: help for the pin out of the NES JALECO-JF-10
by lidnariq on 2018-11-16 (#229009)

Lum no Wedding Bell is mapper 87 ≅ mapper 101:
https://wiki.nesdev.com/w/index.php/INES_Mapper_101

The PRG and CHR are standard 28-pin 32 KiB ROMs, compatible with almost any other 28-pin ROM.

Re: help for the pin out of the NES JALECO-JF-10
by Fisher on 2019-03-05 (#235628)

Erin's page seems to have the schematic already drawn.
It's a little different, since it uses only one flip-flop of the 74'74.
It can be a different version or my draw has lots of mistakes, like the inverted M2 and /ROMSEL pins. :oops:

I consider my draw a nice try with a somewhat questionable usefullness.
I'm trying to learn how to do this, so it's a nice exercise. :-)