• Investigating the Ninja Tap(4)

    4 days ago 0 comments

    It occourred to me that the Ninja Tap can support the extra buttons of a FM-Towns controller with the aid of a decoder at each tap.

    The extra buttons of FM towns controllers maps to conditions that will never occur:

    SELECT is UP and DOWN at the same time

    RUN (START) is LEFT and RIGHT at the same time

    Then the following addition to the Ninja Tap circuit could support FM Towns controllers

  • Investigating the Ninja Tap(3)

    09/25/2022 at 21:51 0 comments

    User Jipe from MRC (and MSX Village) reverse engineered its Ninja Tap adapter to obtain the schematics


    Luckly I was on the right track, being the most relevant difference the SI inputs of the 4021 being pulled up instead of down.

    The original circuit uses a 74ACT00 chip not only to feedback the inverted state of signal of pin 8 (pulse) but also to drive the 4021 CLK and LATCH signals (maybe this was the main purpose of the '00 chip).

    I have found another error on my circuit. but it was due to lack of attention. Pins 6 and 7 on the input ports were inverted, as D7 on the 4021s shall read the signal of Trigger A and D6 should read Trigger B, not the opposite.

    The redrawn schematics is show below:

    I have also updated the schematics for the Shinobi Tap, but changed the design of the feedback circuitry to avoid contention, and added a second feedback to allow differentiation between Ninja Tap and Shinobi Tap.

    Detection can be performed using the expected states. First set pin 7 to High to release the open collector output at this pin.

    Pin 6 (Write)
    Pin 8 (Write) 
    Pin 7 Read, no Tap
    Pin 7 Read,Ninja Tap
    Pin 7 Read,Shinobi Tap

    New Shinobi Tap circuit:

  • MSX / Atari 2600 driving controller

    09/17/2022 at 21:42 0 comments

    Sketch for the schematics of a driving controller compatible with Atari 2600 and MSX at the same time.

    The circuit uses a rotary switch with integrated push button, and one extra button.

    The integrated switch for the rotary encoder connects pin 9 (GROUND on MSX) to pin 7 (Trigger B on MSX). The common return for the extra push button and for the rotary switch is on pin 8 (PULSE) that is driven low by BIOS by default.

    When used on Atari 2600 the integrated button works as a positive drive the right  paddle input, pretty much like the thumb button on the omega race booster grip (or the LEFT button of a 7800 controller).