6809 mill clone

[Alex Freed <alex_news@alexfreed.com>]

Another update. After a lot of frustration trying to figure out what can 
stop the OS9 disk from running I'm pretty sure that the one image 
floating around the 'net is broken as it tries to start the 6809 
executing at an address that was never loaded.

So I had to think of another way of making sure my board works. I have 
assembled a small interface program from the Mill manual that runs on 
the 6502. It reads the keyboard and writes to the display via a monitor 
call COUT1. The second part is 6809 code using two memory locations as 
mailboxes to read incoming bytes left there by the 6502 and to write 
output to the outgoing mailbox. The 6809 assembler I used (found at
http://koti.mbnet.fi/~atjs/mc6809/) was "A09". The archive came with a 
few examples including "Tiny BASIC". So I assembled it replacing the i/o 
calls with ones working via the 6502 interface. A great success :)
The Tiny BASIC is running just fine proving that my 6809 board is 
operational. Of course it also runs the counting demo from the Mill 
floppy once I adjusted the addresses.

That's the good news. The bad news is that as I said before the 6809 
CPUs for sale at Jameco are NOT the "E" type, so they are not suitable.
I can order a minimum of 10 CPUs from a different source once I have the 
orders.

It is $80 including domestic shipping. Or for $25 you can buy a raw PCB 
plus a programmed CPLD and assemble your own.

I think everyone who expressed an interest knows my PayPal account.


-Alex.