I am trying to simply read and write to a HM6116 SRAM memory. This is the arrangement I have made on a breadboard... the idea is that I can control the /WE and /OE lines to read and write on address "1" while controlling the databus I/O 1 ~ I/O 3.

Well, the first problem is that it doesn't work--the memory does not seem to save the value. Secondly, the memory becomes very hot, and after about 30 seconds of operation, becomes cold again--no matter what arrangement of the /WE and /OE, and the datalines I make. (after it becomes cold, it doesn't become hot again)

I hope you are not laughing your head off at me but I am a complete neuighbh!!


any insights will be greatly appreciated. An insight as to how to make it work will be appreciated even more.





(P.S. there are resistors on the LEDs. I just didn't draw them on the "diagram")

 

You have a lot of inputs that are "floating" - not connected to anything. All INPUTS must have a path to either Vdd (5v) or Vss (GND). You have /OE and /WE connected to 5v via switches, but when the switches are open, the inputs are floating. You need to have a resistor to ground to pull the inputs low.

Same with the I/O pins - when /WE is low, you must have a logic high or a logic low on each input - but when /WE is high, you must not have any I/O pin connected directly to 5v or GND.

You do not have a connection to /CS. /CS must be pulled low to enable the IC.

Have a look at this datasheet:
ftp://server.goodall.com/hardware/ic-docs/HM6116-70(0611W652).pdf
See the truth table on page 3.
You COULD wire /CS and /OE to ground; then simply use /WE to control whether the value was being written to storage or read from it.

 

"...but when the switches are open, the inputs are floating. You need to have a resistor to ground to pull the inputs low."

Did you mean like this?

(I drew a relay since this SRAM is part of the relay computer I'm building. Would the recoil from relay-switching damage the SRAM?)



Also, what strength of resistor should I use if my assumption was correct?




Thank you. Please be patient with me.

 

Actually, I meant to simply add resistors to ground on the IC side of the switches.
10k Ohms should work fine.

You will need reverse-EMF protection diodes across the coils of each relay, cathode towards positive, anode towards negative. Without the diodes, you will "zap" any IC's connected.

 

Ah.. I knew something was wrong when I thought you told me to put a resistor on a ground path.

I hope I got it right this time; I don't want to keep bothering you.

 

I'm not at all certain why you want to use relays.

Relays are very slow, require a lot of power, the contacts "bounce" when opening or closing, and make a good bit of noise.

Unless you're trying to re-create a WWII-era computer, of course.

 

precisely the reason why.



I'm a computer programmer (c++)--always wanted to know how precisely the things that I programmed worked inside.

With the relay computer, I can. It's going to make a great deal of noise and there are going to be lights flashing everywhere. (and cost $500...)


Also, I had a relatively easy time designing relay circuits and soldering them --they are very simple in operation, can withstand almost any temperature and shock that I give them, and I know when a relay is broken & I don't have to worry about things like "floating" voltage...




Anyways, thank you for the help you have given me.