Commodore 64 (C64) forums

Would the Commodore community be interested in an REU up to 16 Mb for the Commodore C-64 and C-128 computers? 1750 compatible if at all possible, and inexpensive enough that it would not break the bank. This idea has been discussed for some time, with some serious interest from several Commodore 8 bit hardware producers. This is were this idea has gone, to date:
http://www.REMOVED.com/forum/viewtopic.php?t=36367

I think it is interesting if it is compatible. It is already hard to support lots of different hardware within the limited amount of memory. We need standards to keep supporting hardware.

I'd like one, but the problem that's been ran into many times is the custom DMA chip that controls the Commodore REUs. It's pretty much unavailable.

I already have a 1750, but what I'd really like more is an internally mounted 1750 (yeah, pipedream), or something in a smaller package. The 1750 is huge, and is pretty wobbly sitting on my Aprosand expander (which is jutting off the edge of my desk so it's pretty wobbly too). Something maybe like the 1750 clone that was released in the early 90s, small and compact.

Yeah that DMA chip in the REU is what most other 3rd party REUs require. So you have to scavenge one from a perfectly get Commodore REU. What Jens has proposed and hopefully makes, is an REU that will not require that chip as it will be a new design that aims for full compatibility.
If you are interested in it being made, send an email to:
shop@icomp.de
and tell him you are interested.

Is anybody good with VHDL here?

I put a lot of money into a prototype 2MBytes low power REU a few years ago. It seems the board I got from the fab was faulty.

Sorry, not me. It would be great if an alternate could be designed as there is no guarantee that the icomp one will happen. Battery backup would be great.

Just in passing, there's a competition started at the CSDb for 512K REU demos. With a few people having already done the obvious effects (set source to RAM expansion, set destination to VIC-II register/ghostbyte, light blue touchpaper) and a few of the less obvious as well it should be interesting to see where this goes!

A new version of the 1Mb or 2Mb CMD clone might be the best bet, as there is not much that supports beyond that.

TMR wrote:Just in passing, there's a competition started at the CSDb for 512K REU demos. With a few people having already done the obvious effects (set source to RAM expansion, set destination to VIC-II register/ghostbyte, light blue touchpaper) and a few of the less obvious as well it should be interesting to see where this goes!

Having some new software that could use maybe up to 2Mb would sure help this idea along. The battery backup idea is a good one, but I found this on the 'net: "I doubt if a battery back-up for a REU is possible. Inside the REU you'll find DRAMs and they are not known for being power friendly. DRAMs also need to be refreshed, some thing the REU takes care of. But IMHO the refresh is triggered by the PHI2 signal coming from the C64/128. If this computer is powered down, there will be no PHI2, thus no refresh. - See more at: http://compgroups.net/comp.sys.cbm/batt ... commodore-" That doesn't sound good.

The REU I was working on used static RAM chips specifically select for having a low power "sleep" mode that draws only 9 microwatts to keep content. A watch lithium battery was enough to keep it going for years.