Re: Mystery Board

[david@uow.edu.au (David Wilson)]

Jeff Lemke <lemke@terra.cira.colostate.edu> writes:

>I've come across a board by "Stellation Two".  The line below that says
>"The Mill".  Copyright date is 1980.  There are 8 chips on the left end
>of the board in two rows of 4, at locations labled U15 and U16 on the
>far left end, and then U1 to U6.  The next chip at U7 is a large one,
>labled 3C1 on the first line, and HD6809EP on the line below that. 
>There are three more chips to the right of that at locations U8 to U11,
>with U11 actually being an empty socket.  There are three more chips
>mounted vertically in respect to each other on the far right end of the
>board, at locations U12 to U14.  There are no other cables or connectors
>on this board, and no writing on the back.

>Anybody know what this board is?

Yes - I have one as well. It is a 6809 co-processor card for the Apple //.
Just like the z80 SoftCard, it allows you to run code written for a different
CPU. Unlike the z80 SoftCard, both CPUs run at the same time (well almost -
about 1 in 5 cycles (when the 6809 does not need the bus) the 6502 gets to
run for a cycle).

What can you do with it?

1)	An Apple Pascal speed up kit was available.
2)	A 6809 Assembler kit that ran under DOS 3.3.
3)	OS/9 Operating system. This came with a daughterboard
	that had a switch and a small ROM (32x4 bits?) that remapped
	the address space of the Apple // so that the screen and zero
	pages were not stomped on by OS/9 programs. The daughter board
	replaced the LS367 buffer nearest the edge connector.

The empty 24 pin socket would take a 2716 or 2532/2732 [not sure which]
EPROM and map it into the 6809 address space.

I have OS/9 but never got it to work on my //e - it worked fine on the ][
at work.

The documentation with it includes circuit diagram and code examples.
--
David Wilson  School of IT & CS, Uni of Wollongong, Australia  david@uow.edu.au