Hi,
I'm working on a project where I need to modify a chip select to only be active at the first half of a CPU's available address range, and disable once the CPU hits the next half. So, an address divider...
You can see my circuit below. What I'm working with is a 8-bit processor with the ability to address up to 64k. Here In my circuit, I have "CS" (which is active for the entire 64k range) in one of the inputs of the AND gate. Since I only want it to be active for 32k of it, I bring A15 into the picture which is connected to the input of the inverter to bring it high (since A15 alone would be low during the first half of memory). Now here's the problem. The output of the inverter is high like it should be, until it's connected to the other pin of the AND gate, when it then goes low! Why is this? Does it need a resistor or something to create a bigger load maybe?? I don't understand it. Why does the output of the inverter go low after connecting it to the AND gate? I know without a doubt that everything is connected correctly.
Help would be appreciated,
Thanks!
I'm working on a project where I need to modify a chip select to only be active at the first half of a CPU's available address range, and disable once the CPU hits the next half. So, an address divider...
You can see my circuit below. What I'm working with is a 8-bit processor with the ability to address up to 64k. Here In my circuit, I have "CS" (which is active for the entire 64k range) in one of the inputs of the AND gate. Since I only want it to be active for 32k of it, I bring A15 into the picture which is connected to the input of the inverter to bring it high (since A15 alone would be low during the first half of memory). Now here's the problem. The output of the inverter is high like it should be, until it's connected to the other pin of the AND gate, when it then goes low! Why is this? Does it need a resistor or something to create a bigger load maybe?? I don't understand it. Why does the output of the inverter go low after connecting it to the AND gate? I know without a doubt that everything is connected correctly.
Help would be appreciated,
Thanks!
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