On Mar 5, 6:12=A0am, Mark McDougall  wrote:
> apple2fr...{at}gmail.com wrote:

[...]

> > Given the large die sizes used in the old days, I imagine it should be
> > possible (given access to suitable equipment) to slice open the chip
> > and examine the die under a fairly low power microscope. =A0This should
> > enable reconstruction of an equivalent circuit. =A0Hardly worth the
> > effort, though, except perhaps for the challenge of doing it. =A0That's
> > assuming that Apple wouldn't be willing to provide details on the
> > ASICs from their archives.
>
> This has been done before - and is being done now - quite successfully on
> several different devices for the purpose of arcade machine emulation. Ve=
ry
> impressive stuff!
>
I love reverse engineering.

> >>> Also, with an FPGA, it is my understanding that you can
tap or probe
> >>> any signal you like by designing the system in such a way
as to bring
> >>> these signals to the FPGA I/O lines. =A0
> > No -- you simply decide what signals you want to be able to access,
> > and build them into your original design.
>
> Actually, it's better than that. Both Xilinx and Altera (major FPGA vendo=
rs)
> provide tools that allow you build a virtual logic analyzer inside your
> FPGA. No need to reserve pins and hack your design to bring signals out -
> you can define which signals you want and add trigger conditions like a r=
eal
> analyzer.
>
Very nice.

> > OTOH, someone with a "development system" could
dynamically compile a
> > particular "instance" of hardware they would like to
use, and then
> > load it into their system. =A0This would be analagous to having
> > reconfigurable peripheral cards in a real Apple II except that you're
> > entire system would be reconfigurable. =A0If you got tired of the Apple
> > II one day and decided you wanted to try out a TRS-80, you'd just have
> > to create a new implementation and you'd have it.
>
> It's called the "C-One". http://www.c64upgra.de/c-one/>
>
Nice to see the minimig project continues to grow.  I am looking for a
platform which can support Alex & Steve's designs but doesn't require
me to buy a $4300 Nanoboard II.

> > I suspect you could load at least 10 68000 cores onto one of the
> > larger FPGAs made today.
>
> The TG68 core in Minimig takes 5,112 logic cells on an EP2C35 (or roughly
> 14%). Using crude extrapolation, an EP3C120 would allow you some 23 68k
> cores. But they're quite expensive!
>
Sure, but the gate count will continue to increase and the prices drop
as we move forward.

> > I hope by tinkering around with reconfigurable hardware based on Woz's
> > design from the 1970s/1980s to gain some greater insight into this,
> > not to mention having some fun and learning a few useful tricks along
> > the way.
>
> I'll have to side with Michael here. I seriously doubt looking at a HDL
> (FPGA) implementation of Woz's design will give you much insight into the
> black magic that he used. It's just too removed from the source, and even=
 a
> "gate for gate" implementation in HDL is still a level of
abstraction awa=
y.
>
I'm afraid didn't express myself clearly.

I believe that retrocomputing is attractive to many people who have
the "spirit of Woz" -- in other words, those of us who appreciate
simplicity, elegance and efficiency in our designs -- whether they be
software or hardware.  These were necessary attributes of both
software and hardware in the early days through the 1980s or so.
Nowadays they are largely forgotten -- even by embedded system
programmers many of whom have switched to what I term "nanny"
languages like Java.

A question that has been forefront in my mind lately is whether or not
the "spirit of Woz" has any place in the IT industry today.  In other
words, is there a place for simplicity, elegance and efficiency of
design outside of certain specialized embedded systems?  The answer so
far appears to be, "no," because as far as I am aware there is not a
single piece of commercial computing hardware I'm aware of that
embodies these principles.  The same applies for operating systems
outside, perhaps, of Tanenbaum's Minix, which has itself attracted
very little interest outside of academia so far.

This is the insight I'm hoping to achieve, and one reason why I
ultimately want to go beyond the original Apple II platform into
something more modern, more practical, and yet which also embodies the
"spirit of Woz."  No doubt my chances of success would be much greater
if other people were interested, but regardless of whether or not this
happens, I intend to have a lot of fun along the way!

--
Apple2Freak
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