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About Danjovic

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    Chopper Commander

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  1. Tristate or Standby depending on either Output Enable or Chip Enable signal is used by the cartridge.
  2. Switch the VCC is not the better option as the second memory can be ghost fed by internal protection diodes. Better use the A12 (chip select) pin. The selected cart will receive the chip select on its pin A12 while the other will receive a GND (on its A12 pin) and stay unactive.
  3. Danjovic


    I wonder that it its possible to mixed the mux from quadtari with the eeprom from Savekey to create a joystick adapter to allow savegames without loose one joystick output. Pin 9 is used to alternate the signals. There is a 100k resistor to pin 5 to make it possible to differentiate this adapter from a Quadtari. All components should fit in a 1" board.
  4. If you prefer a DIY approach for USB adapter, take a look at my Control Freak project.
  5. Yes, the sources for the whole project are on github.
  6. I have just uploaded a new version of the firmware. Some bugs have been corrected, specially the deadlock condition caused by pin change interrupt on pin 9 of 5200 port (Cav control). Using Classic controller library >0.8.1 . From version 0.8.1 the axes values are always returned in the range 0-255, even for knockoff controllers that can only operate in low resolution mode. Added a non-linear curve, that in practice provides a sort of dead band on the center and gets steep at the extremes. The curve saturate close to the edges to compensate some controllers that can not return in full range, even in high resolution mode. Corrected the code that adds the movement of left and right sticks in single controller mode. The resistor R1 shall be the value changed to 1K ohm so the LED on pin 13 of some Arduino Nanos does not interfere with Cav control. Thanks @Chris Belcher for the feedbacks!
  7. That's weird. You mean half of the chip work ok and the other half is out or specs, right? Does it still provide linear variation? If so you can trim the capacitor to match the digipot. Does that happens with either half equally? Any diffetence ifyou tie the not used terminal with the wiper? If you invert the side of the pot would that work as expected ( scale ok but inverse direction of atuation)? Would be too bad to add a second socket for a second digipot? (and some cutting jumpers)
  8. Thanks for the code. It provided me a good insight about the timing related to the detection of the trackball.
  9. From 5200 schematic: Votage that appears on pin 9 is controlled by pin S2 from GTIA. From GTIA datasheet S2 pin is open drain and inverted. Writing 1 to this bit will sink the voltage on the pin. Writing a zero will let the voltage be driven by an external pullup resistor. Simulating the circuit (in ewb), we see that when 0 is written to the pin the voltage at pin 9 drop down to zero volts. And writing 1 to this bit activates the voltage on pin 9 ( in range ~ 4.0 to ~7.0 Volts) depending upon the value of the potentiometer As the GTIA sits at $C000 I have disassembled 3 ROMS to investigate trackball detection: - Pete's test cartridge : No writing to $C01F - Centipede: No writing to $C01F - Missile Command: 3 writes to $c01f 1006: lda #$04 1008: sta $c01f 119e: lda #$00 11a0: sta $c01f 11c5: L11C5 lda $a5 11c7: L11C7 ora #$04 11c9: sta $c01f I was expecting that all three titles dropped the voltage to try to differentiate a trackball from a joystick. Which other games behave or should behave differently with a trackball or a joystick ?
  10. There are at least two DIY SMS paddle alternatives: https://www.raphnet.net/electronique/sms_paddle/index_en.php https://hackaday.io/project/167338-smsx-paddle
  11. Yes, it is compatible. Both NES and MSX paddles made by Taito are the same board with different cable. Some pictures and discussions on forums found on the net point to differences in the values of some components but all should provide similar results nevertheless. If necessary it is possible to tweak the readings by installing the trimpot (R7) instead of the fixed resistor (R1) on the discrete component version. On the digital version the readings can be set ny changing the definitions of MINVAL and MAXVAL.
  12. DIY Vaus Arkanoid controller in two flavours: Discrete and Micro-controlled.
  13. Hi,

    I have a sketch of a circuit for the 8 port NES expander, as well as some code.




    Base is Arduino board (Nano) and plain IDE functions. Some speedup can be done using registers directly for I/O. Code was written to be ported with ease for other micro-controllers, as most of logic is in plain C, letting the IO in macros.



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