More on CUBIX - Was: newbie building a scratch-built computer - test-drb@ccmp.vtda.org

3 Aug 2007

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Subject: More on CUBIX - Was: newbie building a scratch-built computer
   From: "Dave Dunfield" <dave06a at dunfield.com>
   Date: Fri, 03 Aug 2007 07:29:17 -0500
     To: "General Discussion: On-Topic and Off-Topic Posts"	<cctalk at
classiccmp.org>

 > If the whole purpose of this exercise is to
have an old 8-bit system so you
> can program in hex and/or assembler, then you can download an emulator and
> play around with it from there. If you mainly want to run things off the
> various serial and parallel ports then something like the Micro-KIM would be
> useful. 
There's an experience gained by building it yourself that simply can't be
obtained
by playing with an emulator. Building a real/physical computer is a worthwhile
excercise and beneficial learning experience. Besides, friends and family are much
less impressed by a wave of the hand at a PC running an emulator with the statement
"I downloaded that!" then they are by a rats nest of wires, circuit boards,
cables
and such and "I built it myself!"

There is magic in building it yourself however it's constructed be it emulator
or hardware. The magic is that you have to understand it to build it.  Simply 
assembling "it" does not provide it beyond the mechanical accomplishment
though if you study the result there will be knowledge gained.

<<<snippage>>>

...
 Another plug for my CUBIX system:

The system comes with the following resident (runs on CUBIX itself) development
tools:

  6809 Assembler
  ASP - A simple high-level language/preprocessor for the assembler.
  Debugger (breakpoints, single-step, disassembler, all the usual commands etc.)
  Basic
  Forth
  Micro-APL
  C compiler
  8080 simulator
  Text editors / utilities / etc.
  - Source is posted for all of the above except for the C compiler.

I can also provide PC based cross development tools for the 6809 including:

  Hardware Debug Monitor (RAMless - needs only ROM to run)
  Full-up ROMable 6809 monitor (Quite powerful)
  6809 Assembler
  6809 Disassembler (Does symbols, memory block types, comments etc.)
  6809 C compiler
  6809/CUBIX simulator/emulator - Lets you run 6809 code on your PC with ICE
      type debugging capabilities - Also boots CUBIX, provides access to all
      the resident tools etc. 
He may appear biased but those are powerful tools and unlike back when I 
built my Altair or the 8008 before that they are available!

...
 I'm obviously biased, but I think it's a
worthwhile system to build. Depending
on your skill/experience/time available, it should take anywhere from a day or
two to a few weeks to build it. What you get from the excercise is a unique
system that can actually do useful things, and the experience and satisfaction
of having created it with your own two hands. Having built it yourself, along
with the fact that I have released the source code means that you have the
opportunity to fully understand EVERYTHING about this system - down to the
tiniest wire, and the last byte of code - this is something that rarely happens
with modern computers. This system is simple enough that you shouldn't have
trouble following the design, yet powerful enough to be considered a "real"
computer. 
MY $0.02, great teaching tool, good for understanding hardware, excellent for
a look at a straightforward OS example that is very usable.  For an old hand
PDP8/11, NS*DOS and CP/M style OSs CUBIX OS was a real eye opener to different
ways files can be orgainized.

<<<<snippage>>>>

...
 I should also point out that unlike most home-grown
designs, the CUBIX system
is very well documented. Two of the three 360k diskettes that normally accompany
the system are filled with documentation. Over a dozen documents containing
more than 300 pages. 
Therein lies the greatest value.  Even if you didn't build it there is a wealth
of information that applies to any CPU/system.

...
 What else can I say - all of the CUBIX material is
available free on my site.
If people are interested, I could organize it into a separate "building a
CUBIX system" page with more information, additional PC tools and other related
material. Let me know if there is any interest. 
Having built one and meaning to spend more time with it it's a good project
and in some respects less painful than doing a Z80 CP/M machine from the 
ground up.  The key thing is that when operational like CP/M systems there 
is enough software to be useful.  This is unlike the microKIM, CosmacELF 
style minimal systems where hand entered programs of a a few hundred bytes 
are it. 

The other feature is there is a CUBIX SIM and while building you can become 
familiar, read docs, look inside the code and develop software or other 
projects. 

Allison