Recently I've been "hunting" some old Atari 2600 cartridges.
I disassembled a multigame cartridge and was a bit confused about the game-switching circuit.
This circuit switches the game when the console is powered off and then on again:
Although I successfully rebuilt the same circuit, so I can confirm I draw it correctly, I just can't understand how it works.
Is the IC receiving current through the clock pin, how?
Another interesting thing I've seen in this cartridge:
This is the game's PCB.
Many games use a NOT gate to generate the enable pin for the ROM, but interestingly this one uses the /PGM pin connected to A12.
This seems to work as a +CE pin. Cool!!
Can someone please help me to understand the game switching circuit?
Thanks in advance.
Please, help me understand this Atari 2600 cartridge switch
Re: Please, help me understand this Atari 2600 cartridge switch
Yup!
Because CMOS parts are so static sensitive, they often will have diodes as possible to reduce the possibility of static discharge damaging something.