Static-RAM Implementation for Relay Computation

Discussion in 'Electronics Resources' started by sungchoiok, Jul 1, 2011.

  1. sungchoiok

    Thread Starter New Member

    Apr 23, 2011
    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.[​IMG]

    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?
  2. hgmjr

    Retired Moderator

    Jan 28, 2005
    Do you have /CS and /OE tied permanently to ground?

  3. sungchoiok

    Thread Starter New Member

    Apr 23, 2011
    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
  4. SgtWookie


    Jul 17, 2007
    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.
  5. sungchoiok

    Thread Starter New Member

    Apr 23, 2011
    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.