Hi! Below is the circuitry from the ECB 6x0x host processor board which allows a single CPU board to use a 6502, 6809, or 6802 processor. As you can see the three processors are very similar and to make the accommodations requires an extra 40 pin socket and small number of jumpers and resistors. This works very well and several of the N8VEM ECB builders have 6x0x systems which can switch between the three processors at build time.
Thanks and have a nice day!
Andrew Lynch
> -----Original Message-----
> From: n8vem...@googlegroups.com [mailto:n8vem-
> s1...@googlegroups.com] On Behalf Of Andrew Lynch
> Sent: Tuesday, August 21, 2012 7:57 PM
> To: n8vem...@googlegroups.com
> Cc: danwerner21
> Subject: RE: [N8VEM-S100:1070] A new S-100 6502 CPU Board
>
> Hi! For the life of me I can't find it right now but I've seen a simple schematic
> that uses latches and transceivers to extract the full 16 bit data bus and 24 bit
> address bus from the W65C816S. Basically it is the CPU plus a couple support
> chips -- basically similar to how the 8086 does it! It is a full blown 16 bit
> computer with 24 bit address bus. It is a natural fit for the S-100 bus, IMO.
> Basically I recommend finding one of the many W65C816S home brew
> projects and reviewing it. Maybe discuss with the folks at 6502.org also I
> know Dan Werner is very knowledgeable about the W65C816S so maybe he
> can shed some light on this.
>
> Thanks and have a nice day!
>
> Andrew Lynch
>
> > -----Original Message-----
> > From: n8vem...@googlegroups.com [mailto:n8vem-
> > s1...@googlegroups.com] On Behalf Of David Riley
> > Sent: Monday, August 20, 2012 10:49 PM
> > To: n8vem...@googlegroups.com
> > Cc: <n8vem...@googlegroups.com>
> > Subject: Re: [N8VEM-S100:1069] A new S-100 6502 CPU Board
> >
> > On Aug 20, 2012, at 21:48, "Andrew Lynch" <LYN...@YAHOO.COM>
> wrote:
> >
> > > Hi! At this point since the W65C816S is an 8/18 bit chip I would
> > > suggest a
> > > 16 bit S-100 CPU board built around it. Then the board could use
> > > the
> > > S-100/IEEE-696 16 bit extensions and be purely 16 bit rather than
> > > tweaking the S-100 6502 CPU V2 board which is a fundamentally 8 bit
> > > CPU
> > design.
> >
> > My memory of the 65c816 is a bit rusty, but isn't it only an 8-bit
> > data
> bus with
> > an ALE equivalent pin to latch the upper 8 address bits from the data bus?
> >
> > I'm thinking that might make it difficult to make a true 16-but board
> > out
> of it; I
> > seem to recall that the primary benefit of the 65C816 was that it
> > behaved
> as
> > an 8-bit CPU to the outside world (much like the 8088 as opposed to
> > the 8086).
> >
> > Or I could be remembering completely wrong. Either way, I'd be
> > interested
> in
> > a 65C816 CPU board!
> >
> >
> > - Dave=