Modern SRAM Memory Replacement for the Commodore 64

The first computer “love” is the Commodore 64 and I get real excited about new developments and uses of modern tech to allow the 40 year old computer to persist. it’s really quite amazing what is now an obscure, old, 8-bit machine has what is arguably a more flourishing existence than it ever has.

I have previously covered other replacement parts for the Commodore 64 like the new Commodore 64 keycaps and a replacement 6502 (not exactly a replacement). Limited runs of a VIC II Replacement are in the works as well. Now, there is a modern SRAM memory replacement module for the Commodore 64 and this is something I think is quite exciting. The supply of old parts are not going to hold out forever and if vintage tech enthusiasts can utilize modern components to keep these old machines running, all the better!

This memory replacement is for Commodore 64 motherboard assembly numbers 250407 and 250425. These boards have 8, SRAM memory chips, often socketed. This replacement is a PCB containing pin headers that plugs into the appropriate slots of each of the RAM sockets for what I consider to be an incredibly reasonable price of €15.90.

The modern memory replacement module comes in two color options of red and blue.

I really want to commend the designer of this product in that the same PCB is used for both 250407 and 250425 motherboard chip arrangements. The difference looks to be only a few millimeters and provisions have been made accordingly. This board can also be purchased without the pin headers installed for a more DIY experience, if that is your thing. I can also imagine that this would also be useful if you are someone that performs a lot of Commodore 64 repairs and want to keep a single stock item for a variety of motherboards.

Another benefit to this board is that it does fix the VSP-bug for which some Commodore 64s seem to be afflicted. That will open up the ability for certain demos and games that take advantage of this DMA-delay. So, in effect, this could be a very reasonable upgrade or fix for a buggy Commodore 64 as well.

As far as the color goes, I think I really like how the red looks. It stands out, for which I sort of think such a modification should. I suppose, if blending in is more your thing, the blue is a better option. It makes me think, maybe, some sort of RGB option, like you see on RAM modules for many modern gaming machines with those transparent side panels would be a big hit with those that like to “trick out” their Commodore 64. I am now imagining RGB lights on the RAM with one of those crystal Pixel wizard 64C cases…

Final Thoughts

My lack of knowledge about the electrical signaling has me scratching my head a bit about why not all pins in the sockets need to be plugged in but since this is working, the people much smarter than me has it all figured out. Looking up the specification of the SRAM chip it is 1,048,576-bit. To my understanding, that means it is 512k of RAM. It has me wondering, how feasible would it be to have a module like this also be a 1 megabyte RAM upgrade with all the bells and whistles of the REU or GeoRAM or maybe the NeoRAM unit? I admit, I am very ignorant on this subject but a middle-aged dude can dream, can’t he?

Commodore 64c Replacement Case
LY62W1024RL Datasheet
Difference between GeoRAM and REU plus some other stuff on YouTube

5 thoughts on “Modern SRAM Memory Replacement for the Commodore 64

  1. That’s a very nice price. I have a 64 on the shelf that doesn’t run (Micron RAM in it, so of course that’s the first suspect). And someone with mediocre soldering abilities like me could do the repair, it seems.

    I’d seen a product like this on Ebay and wondered about it. This is the first review of one I’ve seen, so it’s nice to hear your firsthand experience with it.

    1. I haven’t actually purchased one but the next memory failure I get on a C64, this is what I am purchasing. In fact, now I am on the hunt for another Commodore 64, just so I can do this repair. 🙂

  2. It’s 1024 megaBITS, so as you said 128k x 8 bits. as each byte is 8 bits, it’s 128ckilobytes. Granted, still twice the needed amount.

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