Re: All this talk of a new GS...

[Jonas Bevren <jbevren@yahoo.com>]

On Thu, 3 Feb 2000, Frank Carney wrote:

> Date: Thu, 03 Feb 2000 22:45:43 -0700
> From: Frank Carney <frankc@cyberhighway.net>
> Newsgroups: comp.sys.apple2
> Subject: Re: All this talk of a new GS...
> 
> Jonas Bevren wrote:
> > 
> > On Thu, 3 Feb 2000, Phoenyx wrote:
> > 
> > 
> > Hm.  That's definately a consideration.  I dont swear by not building a
> > standard-form motherboard, but in the moment of considering the feasiblility
> > of writing clean-room GS roms, you failed to consider the feasibility of
> > re-structuring the IIgs's hardware.  I find the first to be far more likely
> > to occur than the second.  I'd love love love to see something like this
> > come out, but not only for the apple2 world.  We love our apple2's (I miss
> > my laser128 like the desert misses the rain), but other poor saps need some
> > help too (ie the Atari scene, commodore, etc).  But, since we're on an
> > apple2 group, let's focus on the most important stuff: the apple2 =)
> > 
> 
> I agree, this needs to be a drop in for the original case.  
> 
> Lets look at this on the cheap side of hardware development as well as
> the cheap side for hardware.  I am sure there are chips that give you
> quite a bit of flexibility in supporting new processors, but the cost to
> develop this may be very large.  I was hoping to design this baby using
> old motherboard parts laying around the house.  I know some things will
> need to be new, but I have got at least ten motherboards for 386 and 486
> systems.  When you start talking about supporting SDRAM and hard drives
> the cost for development goes way up.  If this thing could start with
> logic chips, cpus, and mayber gals for glue then the cost is much
> lower.  

Right.  Using some complex logic array to interface between the 65816 socket
and the host CPU would be the best solution.  Perhaps something we can
program from a measly parallel card (there are a few like that, they use two
lines, one for bidirectional data, the other for unidirecitonal clock).  All
you'd have to do is manually twiddle the port lines.

While the 386 may be lying around in your place, I dont have any (donated
them all to people wanting to learn basic linux skills).  However, if you
_do_ get it working with a '386, it shouldnt be too hard to re-adapt it for
other x86 processors, since most share the same style of bus.  In the long
run, it will be cheaper to grab an old socket7 cpu and an mvpIII chipset,
and go off with it.  My K6/233mhz _and_ my mvpIII chipset motherboard costed
$110 together, and I'd honestly pay that to see my IIgs scream like win98 on
a K7/500 =)

> Remember this is a hobby and not everyone has access to storage scopes
> and other necessary troubleshooting hardware.
> 
> On the software side I just thought it might be useful to provide a
> monitor program for troubleshooting.  Another possibility would be a
> terminal that could either use a dedicated port or one of the IIgses
> ports.  Maybe it could even download new cores for development.  Again,
> it could be used to support other systems like the Atari and the
> Commodore by making different cores!

You know, that's a rather smart idea.  you'd have to remember, though, taht
the atari has a modest 6502 powering it, and the c-64 has a 6510 (=6502 with
internal 5-bit data port and DMA support on-chip).  The superCPU accelerator
also uses a 44pin PLCC form for the 65816.  While I'm not against doing
these, you'd have to provide adaptors. =)

> There is one thing that needs to happen before more things are added. 
> Someone needs to get something working before to much discussion of how
> hard it will be.  From what I understand of open source projects you
> have to have a working program before a project will really take off. 
> Anyway, it is a thought.

Well, if we'd all like to begin such a project, let's get started. =)

-Jonas