1. Not old. Vintage. :)

Keeping up with the Jones's

Discussion in 'SIG: Atari 8-Bit Hardware' started by M.D.Baker, Nov 18, 2020.

  1. by M.D.Baker

    M.D.Baker Chief Officer

    Blog Posts:
    Well, for the last year or more there has been a lot of discussion about 2 or more button joystick mods on AA, and new and converted software. With the release of the TOP NOTCH shooter LAST SQUADRON which supports 2 button joysticks, I finally decided to mod my original Genesis/Megadrive controller (I no longer even own a Megadrive/Genesis anyway and will get controller with one if I ever buy again) to have all 3 buttons available as there are even a few hacked classic games that support 3 buttons now. Then I started down loading dozens of converted games from uploads and links in the Joy 2B+ thread on AA: https://atariage.com/forums/topic/278884-2-button-joystick/#comments
    Buttons 2 and 3 just use the Paddle POT0 and POT1 inputs via connection to +5v pin 7 through 330 Ohm resisters This bit is unnecessary with the Genesis controllers as the 330 ohm resisters are already in place once the IC is bypassed.

    I merely copied the mod from the photos on page 13, post 317 of this thread, making only one mistake going off the picture that didn't allow the controller to go right, then connected to the correct bypass where the multi-plexing 74HC157N chip that was removed. These images are lifted from the post on AA and not mine. Though I made a couple of adjustments like the two jumper wires going to pin holes right next to each other I just soldered the pads on the other side together instead of using wire. Wires 5 and 7 (coming from the cable and attaching to the PCB (they are clearly marked 5 and 7 where the cable wires solder to the board) have to be swapped as well (shown swapped in the second picture) and just the five connections jumping the proper connections across where the removed IC's pin holes are left.

    Lots of great games have already been hacked to support 2 or more buttons, so no more space bar, or second controller, or direction pad activation of special weapons, etc. Just multiple buttons instead for better arcade action.Literally dozens and dozens of hack conversions so far and probably about a dozen new games are out or on the way soon with two button options.

    For example, there is a 2-button hack of Commando now, so you can use the second button to throw grenades instead of pull down/back on the joystick while holding the button to accomplish the grenade toss! Now the game really does play as good as the 7800 version.

    Another, Screaming Wings, by Red Rat received a 2020 version with some slight graphic improvements, and improved game play including the a second button to simply push to do a loop and avoid enemies instead of reaching for the space bar and having loss of control for a second to accomplish it in a fast paced game. A HUGE game play improvement there with a quick avoidance tactic and no loss of control and possible tragedy while chancing to reach for the space bar, or mostly just never using the move and having a lot more collisions and much shorter games.

    Star Trek Strategic Operations Simulator has 2 and 3 button versions now. The 3 button version move the fire Photon from the down directional to the B button, and the Warp-speed that use to be a combination of fire and down is now the C button. I've already doubled my high scores in these games with just one evening with them.

    This is a simple mod for even the beginner with a soldering iron, solder and de-soldering braid which is all I used in this mod. But just to make it totally clear, unlike the picture alone that caused me to make one error, the jumper wires are as follows: pin 1-pin 13, pin 3-pin 4, pin 6-pin 7, pin 9-pin 11 and pin 10-pin 12. That's all there is too it. This is only for the older, original 3-button controller model number 1650 (imprinted on backside) made in China, with the DIP mount 74HC157N. Newer ones have a surface mount multi-plexing IC and different layouts. Save the 74HC157N IC; 74LS157N IC's are used in most Atari equipment somewhere on their boards and the newer HC versions are pin compatible with less latency and power consumption to boot!

    MDPad1.thumb.jpg.477e92400e0f42e4b8373ba10b8b0556.jpg MDPad2.thumb.jpg.7797047ea68c06e478f208bfc0a1724d.jpg

    Of course there are other mod options from complete DIY arcade joysticks to just modding regular Atari after market 2600/800 that happen to have two buttons that normally work as the same button, to a mod for 7800 European style pads and even the original and totally uncomfortable 7800 prolines.
    Last edited: Nov 19, 2020
    Andy Barr likes this.
  2. by Paul "Mclaneinc" Irvine
    Paul "Mclaneinc" Irvine

    Paul "Mclaneinc" Irvine Chief Officer

    Blog Posts:
    I like the mod idea but I best not do it as I might accidently plug it in to my C64 and they blow with a mega drive pad in..

    The poor old PLA would be toast :)

    Its nice that people hacked the games to use the extra button(s), in my days of playing my brother at Defender I would have just loved it mapped to a button instead of my sodding foot :)

    Bad enough it was a 400 so it needed a good press and a spray of air freshener after a bunch of games :)

    I just can't keep up with all the mods here there and everywhere, the inside of your machine looks like a patch board with a spiders web of wires everywhere. But I do like the fact people do these mods, its help keep the machine more current, things like Fuji-net impress me, who would have thunk it, a networked wifi atari. The only thing that's a bit annoying is I can't go to an Atari place and not see Mr Cherryhomes with multiple threads about it. Bit over kill imho but its a clever device so I get he's proud of it.
  3. by M.D.Baker

    M.D.Baker Chief Officer

    Blog Posts:
    While I'm not completely sure why a Megadrive pad would blow a C64, my guess is there is a bad power loop/short since the C64 would be sending +5V to pin 5, so on the Megadrive controller +5v is being sent to the 74HC157N multiplexer constantly through an intended output pin and that +5v is feeding back out of the IC somewhere else and back to the Commodore where it becomes detrimental. Pins 6, 7, and 9 on the commodore and Atari computers all go through the multiplexer IC (TL, TH, TR) on the Megadrive controller. But on the Atari the +5V through the IC is feeding back into Paddle B of the Pokey which doesn't seem to effect the Pokey adversely if at all.

    But since this mod moves the +5v line to the proper pin 7 for Atari and Commodore alike, and the multiplexer IC gets completely removed (which might cause some type of power fee-back loop through the cable to the wrong circuits on the C64) my educated guess with 98% confidence is that after this modification, the controller would no longer have an adverse affect on the C64. unless what ever circuit or chip that handles the POTY and POTX can't even handle voltage through a 330 Ohm resister either, while the Pokey can make perfectly good use of it.But looking at the chart, POTX and POTY on the C64 are also referred to as button 2 and button 3, which is exactly what we are using those same POT pins for on the POKEY, that everything would work perfectly fine on a C64, if any software did use POTX and POTY for extra buttons on the C64.

    The chart below shows how Atari & Commodore match up with their pins and how the Megadrive pad is expecting +5v on pin 5 coming in, but instead is getting it on pin 7 which is sending it through the IC and it's going out and feeding back through one of the contoller cable lines into the C64. With the IC removed and jumpers added, even if it's due to the IC output back to the C64 on a wrong line causing damage.

    With +5v connected correctly for use on Atari/Commodore machines and the 74HC157N multi-plexer IC that is not used in Atari/Commodore controllers anyway,removed completely, no stray power/signals exist anymore to feed back into the C64. The entire megadrive pad circuit is changed to that of standard Atari/Commodore pin out and just using the paddle inputs for buttons instead. So I am almost positive that this would allow the Megadrive controller to work safely on a C64 afterward.
    Last edited: Nov 19, 2020

Share This Page