IGNORE THE REST OF THIS POST,AS HERE ARE THE METHODS ,WITH THE KNOWLEDGE OF THE ASSEMBLERGAMES EXPERTS TO MAKE IT POSSIBLE.
This simple little thing has turned into a right pain in the arse, and i'm just about ready to give up with it .
I've tried connecting up a 74HC74 ic to my sms 1 ,using part of simonbelmont2's mega drive guide below(which is adapted from the one on assemblergames).My sms1 is a UK pal version,with the 3 solder pads ,left is ntsc(ground), centre is the signal and right is pal(+5v) and i've cut the underside linking trace, between pal and signal.
My connections to the 74HC74 are like this;
SMS NTSC solder pad(gnd)to pin 7 (gnd)
SMS PAL solder pad (+5v) to pin 14,1,4 (Vcc)(1R'd)(1S'd)
SMS SIGNAL solder pad to pin 5 (1Q)
74HC74 pin 6 (Q') to pin 2 (1D) of 74HC74
74HC74 pin 3 (Q) to the SMS's IC 315-5216 pin 22 reset
At the time,i left the LED off,but today i tried connecting up my bi-colour LED .It's 3 legs have the middle one as the anode and the outer legs are cathodes,so i assume this is a common anode LED ?
Well i couldn't get it to light up red then green,just 1 colour for one region and off for the other and i'm stumped with how you would connect it to work properly.
So i switched to two separate LEDs ,and connected PIN 5 Q to the SMS signal pad and also to a POT which is set to 400 ohms.This is then connected to LED 1's anode and to LED2's cathode. Then Q' to LED 1's cathode and LED 2' anode ,as per the picture (this is all on a breadboard )!
When i press reset,there's no rapid changing of the LEDs,what happens is this. LED 1 will be on when i switch on the sms and it will be in PAL mode,I can hold the reset button for half a second ,the sms will reset and LED 1 will stay lit,but when i let go of reset , LED 1 will go out and LED 2 will come on and the sms will be in NTSC mode.Now if i try the same thing again, sometimes it will do the same and revert back to PAL,but other times the LED will switch off as soon as i touch reset (now both LEDs are off)and after half a second i release the reset button ,and the LED that went off,comes back on and it's still in the original country mode it was in. This has happened 3 and more time in a row before it corrected itself .
Other times i have to tap the reset button,another time ,if i hold the rest button too long,the sms will reset to a black screen and needs switching off then on.There has never been an outcome like what you see in any of the switchless video's,where you hold the button for a time and the LED switches colour to show you it's in the new mode and you can release the button.This just doesn't happen for me.
I've also tied all the 2nd flip flop's input pins to vcc ,then i tried them at vss.
Just to be thorough ,this is an 74HC74N positive edge trigger and i'm only using 1 flip flop which i assume is correct for only having one output signal with an sms ,unlike the 2 outputs which the mega drive needs .
If i left the sms out of the connection and just prototyped the circuit on my breadboard ,would the LEDs toggle on and off with a set time between each high low status ?