ADDRESSING:
A9A2A1A0 could hold 4 bits. 0-15 in decimal. And 64 high in the column. I don't exactly still know why each column is a separate I/0 because the data is not serialized, only paralleled meaning each I/O can only represent a 1 or 0 at a time. That made me a little weary but I decided to press on.
Timing:
Next up was timing, how was I going to read and write into the chip and tell it to respond to my every command? The chip is pretty simple, there's 2 latches. One labeled W and one labeled S. To read,
W had to be logic high and S just had to go low. As long as there was a crossover between them you could read. To write was a bit more complicated with a few added steps. First, S and W need to be high. Then input the logic high/low onto each corresponding address bit. REMEMBER: A8-A3 were column addresses. So that allowed us 64 columns high. A9,A2,A1,A0 allowed us 16 memory locations of 4 bit words. So the chip was capable of 1024 four bit words or 4096 bits!
I figured I'd wire up the chip to a breadboard and put in some dip switches! Here was the result:
It worked to an extent. It was noisy but I could certainly read and write from various memory banks. I then figured I'd write a little code on my STM32 microcontroller and really get this puppy going. I'll save that for the next post!