View Full Version : old ram chips I.E. 4116

June 7th, 2008, 01:09 PM
on the old ram chips like 4116 there is a dash 1 or 2, this indicates the speed. As a -3 is 70 ns I think. What about refresh time? What are they and where can the information be found? thank you

June 7th, 2008, 02:17 PM
As a -3 is 70 ns I think
Depends on the chip.

What about refresh time? What are they and where can the information be found? thank you
The manufacturer's data sheet is the authoritative source for the specs of a particular chip.
Free data sheets can be obtained from the following web sites:

Dwight Elvey
June 7th, 2008, 05:08 PM
Most older chips require a 128 cycle refresh in 2 ms.

nige the hippy
June 8th, 2008, 05:26 AM
yes, check manufacturer's data sheets, but be aware that things like refresh (time AND cycles) often vary from manufacturer to manufacturer, it's no use relying on generic part numbers.

Dwight Elvey
June 8th, 2008, 07:07 AM
Refresh times were standard for the 16K parts, except some of the TI
parts that needed 256 cycles. These were still 2 millisecond.
The dash numbers were manufacture dependent. These
would require looking up.

July 16th, 2008, 08:54 PM
If you haven't found a datasheet yet, I have one from Motorola. The dash number is specific to the Vendor, hasn't always been a standard convention to describe the speed.


July 16th, 2008, 10:50 PM
Worse, on some early DRAMs, such as 2109, the number indicated which 8K half of the 16Kb DRAM was the "good" one. I've still got a few of those.

July 17th, 2008, 11:56 AM
Yes, Mostek, I believe, used to sell "half-bad" 64K x 1 DRAMs to Tandy for use in their CoCo 32K upgrade kits.

Each set had a little note in the chip case saying "upper" or "lower" so you could set a jumper on the board to coincide with the good "half" of the chip.

July 17th, 2008, 12:57 PM
Mine are Intel 2109's; CERDIP with the soldered-on lid over the chip. I was given a bunch of these by the Intel sales rep because 2117s were in very short supply (anyone remember when outfits were being burgled in Silicon Valley for DRAM?) and he had no 16K samples.

Eventually, I sifted through the lot and populated a 64K DRAM board with the ones that would pass muster as 16K chips. The remainder ended up in the trash, but I still have the 2109's that passed as 2117s in my hellbox.