12 Dec
2008
12 Dec
'08
10:09 p.m.
On Fri, Dec 12, 2008 at 4:06 PM, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
Well, part of my motivation for doing this is that I'm really an
operating systems guy, so in a perfect world I'd be able to make
something I could hack around with easily. With that in mind, I'm
thinking a serial terminal interface, but also including a front panel
with toggles and lights to play with. It would be really fun to go so
crazy as to do a PDP-11 to the point where I could boot one of the old
OS's, but that may be too ambitious for me at this time (can you even
buy PDP-11 microprocessors anymore?).
Given my druthers, I'd go with a 32-bit system, but I'm not sure if
that will increase the complexity beyond my abilities. I'm competent
with soldering and ok when it comes to breadboarding; things could
quickly go downhill if I tried to assemble on perfboard since I've
only tried that for very small circuits. The whole process of
assembling a computer system from the chip level is new to me, so any
tips would be appreciated. My reasons for preferring 32-bit is that
the potential capabilities are much greater.
What does it take to do video (bitmapped) output, by the way? That
would be especially interesting, in my opinion.
John
--
Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn
Hi everyone
As a 4th year computer engineering student with a part time job, I
definitely have too much time on my hands, so I've been thinking about
doing something like building my own computer. I remember playing with
the 68k SBCs back in my assembly class, so I thought something from
that family might be an interesting choice. It's ambitious, but
ideally I'd like to do 16/32 bits and a few megs of memory.
Have any of you built something like this? I'm looking for links to
I've built several machines from scratch, but never a 68K-based one. But
I do feel that's a pretty good choice for a processor :-)
I would start by tracking down a _second edition_ of the 'Student Manual
for the Art of Electronics' (that may not be the exact title, but if you
can't find it I'll dig out my copy and post more details). This is the
'laboaratory book' for the famous 'Art of Electronics' book (which you
should have anyway :-)), and the last few exercises are making a
68008-based computer (so 8-bit data bus) with something like 8K of static
RAM a bit of I/O, etc. You won;t want to copy that design, but it'll give
you ideas.
As regards RAM, I really would use static RAM, at least to start with.
It's a lot easier to work with than dynamic RAM, and SRAM is getting
pretty cheap these days.
You also need to think what I/O you want. Do you want a toggle-switch
panel to load ROM, a monitor program (hex keypad and display, or an ASCII
terminal interface?), a bootstrap for some larger OS (to be loadrd from
what device?) and so on. Personally, I'd probably add a serial port and
have a simple machine code monitor in EPROM, but it's up to you.
-tony