DRAM replacement relevance

[eslapion]

Hi everyone,

I am Eslapion and I have been doing electronic things for the Commodore VIC-20 and 64 since 2006. However, I am also fascinated by the Colecovision and consider the possibility of making small electronic modules for this machine.

 

Recently, I have started offering modules for the C64 and C128 which replace the DRAM with a single static RAM IC and consumes very little power and is much more resilient to problematic power supplies.

 

I have noticed the Colecovision uses 16k x1 DRAM ICs (4116) which require 3 different voltages to operate. I know I could easily make a module which replaces all 8 ICs with a single IC of static RAM which operates with only 5Vdc and consumes less power than a single LED.

 

The question is: Would that be useful to anyone ?

[ChildOfCv]

There is a solution that replaces the 8 chips with a different 8 chips that require only one voltage, but nobody has attempted to replace them with a single chip.  It could be useful though, as even those newer chips are probably in the discontinued state by now.  I guess your single-chip solution uses x8 DRAMs instead of x1?

[eslapion]

On 10/16/2019 at 6:50 AM, ChildOfCv said:

 I guess your single-chip solution uses x8 DRAMs instead of x1?

I don't know of any legacy DRAM which has 8 bits. I use a pair of logic ICs to perform demultiplexing and I use a single static RAM IC. It consumes about 3 mA of 5V only.

 

In the past I thought of using a pair of 4416 (16k x 4) DRAM but even these have vanished.

 

[Ruggers Customs]

On 10/18/2019 at 12:37 AM, eslapion said:

I don't know of any legacy DRAM which has 8 bits. I use a pair of logic ICs to perform demultiplexing and I use a single static RAM IC. It consumes about 3 mA of 5V only.

 

In the past I thought of using a pair of 4416 (16k x 4) DRAM but even these have vanished.

 

Hi there Eslapion.  Right now the going replacement for the 4116s are the 4516s (which I'm fairly certain you're already aware of) but those will eventually become scarce as NOS sources start to dry up.  As far as the what you're suggesting, I'm kind of in the works of building something similar with newer parts to replace the 4116 chips all together.  Just a few latches, a hex inverter and the static ram chip.  All are parts easily available, still in production and will be for the foreseeable future.  It's actually based off of the ZX Spectrum ram module iirc and someone actually made a variant for the ColecoVision about a decade ago.

 

It's on my list of stuff to do but my workload keeps pushing it back.  However if someone beats me to the punch in making them then I don't think I'd be mad about that at all.   As long as they don't make it overpriced.  I estimated I could make them and resell them for 15 to 20 bucks a set.  That's a worst case estimate, hopefully I could get them lower of course.  

 

 

Edited October 19, 2019 by Ruggers Customs
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