Re: [uCsimm] Why was the 68000 bus not exposed

From: James McCombs III (
Date: Wed Sep 13 2000 - 14:34:49 EDT


    I like your idea. If I could got to more on the processor pins, I
could do a lot more with the uCsimm. Even load my own OS. The MC68328
supports downloading of code, I would love to try it out in some of my
proto circuits. The uCsimm is a GOOD design that could be made better if
all the processor pins came out to the connector. I would buy allot
more of these units.

James wrote:

> Hi,
> I know that this comes in a bit late but I have only just joined this
> group and ordered my uCSimm (awaiting delivery) now.
> I have too fairly fundamental questions:
> 1. Why was no IDE interface designed into the uCSIMM?
> 2. Why was the M68K bus not exposed for use by the
> experimenter. When you look at it the IO is pretty pitiful considering
> the plethora of IO available at the CPU. This makes retrofitting for
> Q1. a lot more difficult.
> Exposing an 8 bit M68K bus would have fitted on a 72 pin SIMM.
> Alternatively everything (and more) could have been exposed on a
> 168pin SIMM. Sure it would have been larger but definitely much more
> functional and useful.
> Am I insane or is there a reason why the device was made this way?
> Don't get me wrong. The uCSimm as it currently exists is an incredible
> piece of kit and something that everyone involved should be proud of.
> Perhaps what is needed is a new project group to design a uCSimm Mk
> II. It could be based around the newer and faster MC68VZ323.
> The new device could have the following integrated peripherals:
> - IDE interface prehaps with DMA support
> - Colour LCD support (built in to the MC68VZ323)
> - Ethernet
> - Full MC68K bus exposed for additional peripherals. This
> would make it easy to develop new powerful peripherals such as high
> speed mutichannel A/D samplers or whatever.
> Constructed as a 168pin SIMM stick would allow suitable expansion on a
> similar backplane to the gardener board.
> Anyone out there interested in working on such a project or is there
> something out there already (in which case I will cancel my uCSimm
> order and buy that soemthing else).
> Regards,
> Richard Laxton

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