Re: Are there any 65816 card schematics?

[Tristan Mumford <xtristan.xmumford@xgmail.xcom>]

Michael J. Mahon wrote:

> Tristan Mumford wrote:
>> Sean Fahey wrote:
>> 
>> 
>>>  To: Tristan Mumford
>>>There are two kinds of 65816 options (generally speaking).
>>>
>>>The first type is the slotted variety - which can either work
>>>cooperatively with the rest of the system or it completely takes over the
>>>system when active. These options tend to be software driven and
>>>therefore not very compatible with
>>> other applications except those that are written/patched to support it.
>>> These
>>>kinds of cards are generally intended for cross-platform development,
>>>scientific analysis or some other "high-end" computing task.
>> 
>> 
>> I seem to recall hearing about a Z80 card that cooperatively used the
>> system. It needed complex software. Sort of like the C64 CPM cart. It was
>> up to the 6510 to handle interrupts still (I think).
> 
> Most coprocessors ran cooperatively with the 6502 so that the 6502
> could do I/O, particularly Disk ][ I/O.
> 
> Many coprocessors used the DMA line to hold off the 6502 to access
> main Apple memory (for buffers or graphics), even if they had plenty
> of program and data memory "on board".

Indeed they do. It's a very useful line. Adding another processor would be
painful without it.

> 
>> Are the complete system takeover style cards still a slave to needing
>> custom patched software while the '816 is running in 6502 compatibility
>> mode?
> 
> The one's I know of (like AE) ran 6502 software, but that's up to the
> designer...

That's true. I'll have to get a good look at a schematic if possible, so I
know what can and can't be done.

> 
>>>The other 816 option is the processor replacement - and here we have a
>>>couple of sub-options.... some accelerators for the 8 bit II took an 816
>>>no problem - and while you could execute those extra ops, strange things
>>>may happen, plus you could only address the usual RAM locations.
>>>
>>>Then there are the socket boards - like the Applied Engineering 816,
>>>which is a board that mounts over, and replaces the 6502. It has strap
>>>cables that can be hooked up to a RamWorks card and... if I read
>>>correctly, a Ramfactor board... which would give it 2-8MB accessible RAM.
>>>
>>>I have one of those AE cards, and it may get cloned eventually.
>> 
>> 
>> They sound pretty good.
>> Memory addressability is the main issue though. Like I said in another
>> post I could just make a banked memory card, but... well, I just don't
>> want to do it that way :)
> 
> Accessibility of additional memory is one reason for putting the '816
> on an Auxiliary Memory card.  That could give the '816 a linear view of
> the memory and the 65(C)02 the conventional banked view (though seeing
> chunks of the memory as "stack" is probably not very handy ;-).

Once the 65816 is enabled does it actually matter what the original CPU
sees? especially if it is held in the disabled state. I think I'm concerned
about treading on the toes of the I/O in the system more than anything
else.

> 
>> Apart from when I'm just messing around on it, it'd be running a custom
>> build of Contiki. There would be a fairly noninteractive (to the local
>> user) server app. Either the multiplayer 'vaguely roguelike' game I
>> started writing for this purpose at the beginning of the year, or
>> something else as yet undecided.
> 
> Actually, there was a very nice integration of a 65816 with an Apple II
> compatibility mode--I think it was called the IIgs.  ;-)
> 
> Seriously, why not run your large-memory apps on a IIgs and save
> a lot of non-standard trouble?

A IIgs has been on my wishlist for over a decade. Every one I have found has
been over 1000km away and at least $100 more than I'm willing to pay for
one. So I use what I've got.

Thanks for your help. I always appreciate it. 

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