Re: New GS/new accelerator

[Frank Carney <frankc@srv.net>]

Charles Stephens wrote:
> 
> "Jonathan Schattke" <wizwom@ripco.com> wrote in message
> 38B85C70.F7F3F088@ripco.com">news:38B85C70.F7F3F088@ripco.com...
> > bobryan9@my-deja.com wrote:
> > > Facts:
> > > Apple IIs have a 1 Mhz bus.
> > > 1 Mhz video
> >
> > > Use an existing motherboard: Already built.  Just interface a 65816
> > > (65832?  65864?) to the processor socket.  Create a 65816 video
> > > driver.  Build either adaptors (plug adaptor into PCI/ISA socket, plug
> > > apple II card into adaptor), or make a PCI/ISA card that has a cable
> > > that runs to a card you built for the GS.  It could be just a straight
> > > through cable/card combination.  Just connect the Data lines.  You
> > > might want a buffer.
> > >
> > > Advantages:  Use all your own Apple II cards.  Use high resolution
> > > video capture and other types of PC interface boards.  High speed disk,
> > > memory, video access.
> >
> > This, indeed, is a good idea
> >
> > The transfer is at the native speed of the IIgs processor, but the
> transfer from
> > _what_ becomes the question.
> >
> > I think the cheapest solution would be a PCI peripheral card to interface
> to a
> > IIgs through the processor socket.
> >
> > Minimum would then be an I/O processor, which would map the I/O portions
> of the
> > IIgs into the PCI memory space, and use write-through caching for the IIgs
> RAM.
> > This would require a very minimal processor on the board, since all it
> would
> > have to do is handle the holding of the signals properly for the hardware
> > emulation of the 65816.
> >
> > The software emulation would be handled by the main proccesor, either a
> powerPC
> > or an Intel PCI motherboard could be used.  In fact, you could have your
> Wintel
> > machine be your most powerful IIgs peripheral :)
> >
> > This would just be a souped-up ICE, in principle.
> 
> That is a horribly expensive idea.
> 
> Why not just build a MMU/cache controller around a faster 65816 and have a
> slot for a single DIMM and if there is room, a USB port.  KISS, people,
> KISS.
> 
> cfs

Make it cheap!  I am making use of old hardware in my design.  I found
one board I would be tempted to use though.  It is  a 486 with
networking, ram, rom, PCMCIA, VGA output, and everything a PC needs on a
board that is the size of a 3 1/2 inch drive!  It is about half an inch
thick!  It costs less than $300 in quantities less than 10.  I was
tempted, but decided I would be a computer guru and continue working on
my 8088 design.  BTW I will be using GALs instead of TTL chips cause
they are soooo cool!  My programmer can handle them and I pulled at
least 20 of them off of a 386 motherboard.  Anyway, I am in the process
of wire wrapping my base processor unit with some and a little IO. 
Eventually it will be a printed circuit board with some minimum
hardware:

1 8088 CPU
2 Decoding Logic (to decode and buffer the busses)
3 8259 Interupt Controller (this will be needed for timing IO to the
IIgs hardware, I think :)
4 8255 IO Port (Maybe two of these)
5 8250 Serial Port (I want this because I will develop firmware than
will allow me to download the emulator into non-volatile RAM or an
EEPROM or ...)

I like the GAL chips because you can reduce the number of chips needed
to decode memory and other neccesary, sometimes annoying details. 
Besides they give you flexibility and that is good!

One more thing about the emulator side.  Could someone work on a generic
(written in pure C) 65816 emulator that could be ROMable.  I have a C
compiler that may generate small enough code to fit in ROM or RAM on a
small machine.  It is Turbo C++ 3.0.

Anyway, this is my update.