I've been trying for about a month (on and off, of course) trying to get the HM-6116 Static-RAM to work with my relay computer. The computer works in 24 Volts, so there are 24-volt relays that switch the current to 5 Volts for the memory to work with.

This is the circuit diagram.

I select an address, select a data pin, and the corresponding LED lights up. Then, I select /WE. If I "let go" of the data pin, the memory doesn't save the value. I have tried other various combinations of /WE selection and data input, but the results are always the same... the data just doesn't get saved. Is there something obviously wrong that I am doing?

 

Do you have /CS and /OE tied permanently to ground?

hgmjr

 

Yes; every pin is connected to the ground unless they are selected.



I really need to get this working... really desperate. This is the last component for my computer and it just ******* doesn't work.

thank you so much

 

OK, I think I see what's happening.

You're depending upon the LED and series resistors to pull the data inputs to +5v if the data inputs are not connected to ground. However, the LED doesn't pull the data line high enough to be out of the "indeterminate zone"; neither a 1 nor 0.

You'll need to add a pull-up resistor across each LED.

 

Thank you SgtWookie & hgmjr. I see that I was flawed in my even the most basic understanding of IC implementation. With my new knowledge, I'll try to draw up some new schematics and see if they work.