Modern A2 successor

["Arkain" <rwking@no.usa.spam.net>]

John,
    I figured this conversation was worthy of a new thread... anyway...

The contest is not such a bad idea. I've never been much for naming things,
only thinking them up and trying to build them. Banana Jr. wouldn't have any
problems at Apple legal, but can you really compare Apples and Bananas? I'm
not sure people would get the association. It would have to be something
marketable that reminds people of the A2.

The computer itself is more like an apple 6. I haven't decided on what cpu
to use, but I would like to have a 65816 as an onboard coprocessor. This way
you could run the old A2 software natively. I'm still too shaky about having
GS support. The GS was a good machine, but I never got to have one and as
such never learned much about it. Also, from the little I have gathered,
Apple goofed big time when designing it. They did a decent job of working
around their goofs, but they still goofed.

To make the 65816 run properly on the bus, since the bus will no doubt be an
order of magnitude or more faster than the chip can handle, I've started
designing a regulator chip. This chip will use the raw bus clock and feed it
through a counter to produce the appropriate 1.02(& 2.04 if I decide to
include GS support) Mhz signal required by the A2 components. This chip will
also generate a suspend signal to allow the 65816 to access the bus.

The MMU, along with handling standard accesses from the main cpu, will remap
the addresses so that most of the soft switches actually go to hardware
ports, memory accesses are carried out in the same way, and i/o accesses to
card rom actually gets to the cards. It's not quite as complicated as it
sounds.

The interrupt controller will be one of the most interesting pieces. Every
device and slot in the system will have it's own interrupt interrupt line.
Each device that requires multiple interrupts will have an interrupt
register to show which interrupt was triggered. That includes the main cpu.
This probably means that I'll either need to build an interrupt manager on a
stock CPU, or design a CPU from scratch.

If you want to know more, just ask. I'll probably throw up a website with
the logical layout when I start making them in Logicad(after I finish
Logicad, that is).

Arkain