1101 RAM - variants, applications, and modern substitutes?

[polaris26]

Hello all - this is my first post in this forum. I am working on repairing a device that uses a variant of the Intel 1101 memory chip and I suspect that it isn't working correctly. The chip is actually marked as MM1101A/A1N and is I believe a National Semi part.

What I am trying to figure out is which variants of the 1101 will work in this circuit (I'm not sure an original 1101 would work), where would I likely find them (like if I had to purchase some scrap equipment to harvest them) and when was the last drop-in replacement chip made for this application? I know that's a lot of info, but there aren't many other web resources for this kind of thing. The device I am working on was made in 1975 so I am guessing there were other contemporary applications for this type of memory, but I don't know which to look for.

thanks greatly in advance,
Dave

[magictom]

Welcome! Intel or AMD P1101A (or C1101A = ceramic) should work. How many do you need?

[isa-d]

Seem there isn't an exact equivalent
I don't know whats is the difference in the "Access Time" of µsF and µsR

[polaris26]

Thanks for the welcome, and the info! I guess I should explain a little more about what I'm working on.

It's a Tennelec MS-2 "Memoryscan" scanner, from about 1975. It uses an MM1101A/A1 to store the saved frequencies that you program one bit at a time with a "one" and a "zero" button.

In this application, the chip has to work with more or less TTL levels - the power supplies for the memory are +/- 6V. I have good power to the supply pins, the addressing counters are working and I have a write pulse to the memory, but the non-inverted and inverted output pins on the memory chip are forever stuck on +6V and -6V respectively, so I think it is probably fried

I am fairly sure that it isn't supposed to be putting out -6V at any time, but I don't have a data sheet. I isolated the outputs from the input to the shift register, but that didn't change the situation. By the way if someone has a comprehensive data sheet for the 1101 or MM1101 that would help immensely.

I would need at least one 1101 type RAM as a replacement as long as it would be compatible with the voltages - I don't think in this application that it has to work extremely fast.

By the way I'm not sure why I'm trying to fix this thing except that I got this far into it and would like to see it work again...


Thanks again,
Dave

[magictom]

Link to the datasheet:

http://www.datasheetarchive.com/dataframe.php?file=DSA-302002.pdf&dir=Datasheets-16&part=MM1101A1N#

The "A1" is faster than the "A", so I'd try to find a P1101A1 or MM1101A1

[polaris26]

Thanks Magictom for the data sheet!

Is there is a list of computers or related devices that used the 1101 memory chip? I am just trying to see if there is something I can source one from - I might even have something in my own hoard somewhere...

thanks again,
Dave