ethan.dicks at gmail.com
Sat Dec 13 18:19:55 CST 2008
On 12/12/08, John Floren <slawmaster at gmail.com> wrote:
> On Fri, Dec 12, 2008 at 5:23 PM, Ethan Dicks <ethan.dicks at gmail.com> wrote:
> > I have a bit of experience with the 68008 and 68000/68010 from the
> > design end (they were used in various released and unreleased COMBOARD
> > products)...
> Thanks for the info
> Can you, ethan, or anyone else point me to a good source of 68k
I don't know about 68008s, those weren't common, even 20 years ago,
but 68000s should be available from the usual sources we trade here -
BG Micro or Unicorn. The actual MC68000 hasn't been made in 12 years,
apparently, but I know where a several dozen could be located quickly
Freescale, as you've already discovered, would be the likely source of
the newer MCUs with a 68K core.
> It seems that they were good enough for the early Sun
> workstations, so they should be good enough for me ;) Their widespread
> use and the resulting information available should be useful too. I'd
> be interested in one of the MCUs you mentioned... were you thinking of
> stuff like Freescale's ColdFire? Those look cheap and I may be able to
> sample one for free...
> To answer your other questions: I plan to use terminals (I've got a
> vt-220 and an ADM-3A lying around, might as well use them).
Easy enough, then.
> Framebuffer would be nice but it's probably a difficult goal.
Framebuffers, unless you were planning on reusing an existing
component, say and ISA video card, can be fiddly to work with. Simple
textual video, as with a 6845, isn't too bad (but have a look at a
late-model PET schematic to see what sort of support logic is needed),
and since there's no character ROM, a straight bits-to-pixels
"framebuffer" isn't hard in and of itself, but then you have to work
up graphics primitives and font routines to see any results (and video
logic is always full of timing issues no matter how you implement it).
> I'd like
> to implement some kind of storage, yes, and since floppies are kinda a
> pain, I guess IDE or CF would be a good choice if it's not too much
It's easy to support PATA and CF cards - there are designs out there
for plenty of microprocessors, and with the 68000, you have a 16- bit
data bus, which is the native size of the PATA bus, simplifying that
interface (to a small handful of chips, really).
> As for networking... depends on how easy it is to put in. It
> seems that other people have done ethernet on homebuilt boxes, so that
> might be possible, or maybe PPP/SLIP to one of my other boxes?
There are encapsulated Ethernet modules for embedded computing now, or
some of the 68K MCUs have a serial port that's fast enough to
bitbang-out 10Mbps Ethernet (I have something like that in a network
appliance called a WebRamp - runs OS68K, has some form of 68302 or
68306 and a 10BaseT media converter). I'm sure the software end of
that design isn't simple, but the hardware end is.
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