Ten no Koe 2 HuC6201 pinout

Discussion of development of software for any "obsolete" computer or video game system.
Post Reply
lidnariq
Posts: 10433
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Ten no Koe 2 HuC6201 pinout

Post by lidnariq » Wed Dec 23, 2020 10:25 pm

I recently got one, and thought I'd make a pinout for it, since I haven't trivially found one elsewhere. (There probably is one, but I haven't found it)

HuC6201 64-pin QFP, 19x13, 1mm pin spacing

Code: Select all

                     no diode -- / 1 .
                    no diode -- / 2   \
                    RAM /OE <- / 3   \ \
                   RAM /WE <- / 4  /\ \/\
                 *RAM /CE <- / 5   \ \ \ \
                 CPU A18 -> / 6  /\ \   \
                    HSM ?> / 7     \
                CPU A9 -> / 8  /\   \
              CPU /WR -> / 9   \ \   \
             CPU A17 -> / 10 /| \/\  /
            CPU A14 -> / 11 / |    |
           CPU A13 -> / 12    |    /
           CPU A8 -> / 13 /\  |  \
           /LED1 <- / 14 /  \  \_/
          /LED2 <- / 15  \   \
         /LED3 <- / 16 \  \   \
     no diode -- / 17   \  \  /
    no diode -- / 18     \  \/
batterygood -> / 19 O     \
    CPU A11 -> \ 20
     CPU /RD -> \ 21
       CPU D0 <> \ 22
        CPU D2 <> \ 23
         CPU D3 <> \ 24
             +5V -- \ 25
              Gnd -- \ 26
            CPU D4 <> \ 27
             CPU D5 <> \ 28
              CPU D6 <> \ 29
             no diode -- \ 30
               CPU A10 -> \ 31
                 CPU D7 <> \ 32


      64\ <> RAM D7
       63\ <> RAM D6
        62\ -- no diode
         61\ <> RAM D5
          60\ <> RAM D4
           59\ <> RAM D3
            58\ -- Gnd
             57\ ?? diode??
              56\ <> RAM D2
               55\ <> RAM D1
                54\ <> RAM D0
                 53\ -> RAM A0
                O 52\ -> RAM A1
                  51/ <- /RESET
                 50/ -- no diode
                49/ -- no diode
               48/ <- CPU A20
              47/ <- CPU A19
             46/ <- CPU A16
            45/ <- CPU A15
           44/ <- CPU A12
          43/ <- CPU A7
         42/ <- CPU A6
        41/ <- CPU A5
       40/ <- CPU A4
      39/ <> CPU D1
     38/ <- CPU A3
    37/ <- CPU A2
   36/ <- CPU A1
  35/ <- CPU A0
 34/ -- no diode
33/ -- no diode
small dot marks pin 1/64. Large dots mark pins 19/20 and 51/52. Text when viewed upright specifies pin 1 in bottom face, leftmost.


There's several minor interesting things here:

1- There are three pins connected to the LED, but the load resistor for the LED is 560 ohms, and I measured 3V across that resistor, or 5.4mA. One doesn't usually need so many pins for so little current.

2- The data bus, A0, and A1 are relayed through the HuC6201, but not A2 and A3. The 2KB (16kibit) SRAM is most likely a square array of 27 bits on a side, so if this was some kind of magic to minimize power consumption by blocking changes in the column selector stage, it should need more address lines.

3- Although there's a bunch of pins that were just never needed (presumably no wire bond, I could measure no diode from ground or to +5V), there's one pin (# 57) that has over- and under- voltage diodes but isn't connected to anything else on the board. I wonder what it is?

* Pin 5 ("RAM /CE") goes through an external pass transistor, enabled by a voltage threshold IC, before actually connecting to the RAM's /CE input.

This seems needlessly complicated for something that should only have needed access to A20 through A11, but maybe NEC had lots of spare capacity on this one packaging line.

(This was my 10000th post according to the forum's count.)

Post Reply